BY fy A

5 thy (ea ieaotia

i tile te

Beet Me mete ee

Habiegy bdo Mebe ba ts

weeny

Veith seeder ie

manyrete

etree) ate

pare hebe

reir Vested te he

" ser Pete

ead wate tte patra

(aM he fa Hale Sie te bette Une de ie Be

Sw tte tte hee

wreta Nee

sae eater Oe Re

Seema

eee Mee A

nye nie Re

ig te EN

ete he te ore

foe tian eh spe tee te ee

Patriotte tra a OHS mye oats ter

ete

arta the edte CORN we Fae

Piet n eel ydy Pa tte de®

ge te ente

tet oe

fo myee eet

ep le

pie Koy wate Me

Ne de aa nia ns

Bin Ba tmutite He

rly cadet teen ne tye ie oe

Low mewng da tiene o tele hee

ete

ahs Mates

yee OS

ing she af wb

ay re taa vee

reel

Hyon He Me te

I Fin Te ty 8 fae

Peretti’

Co ewe

wie’

a aie

vere

bee Cote

eA hid

mylyn

Dal

Hy avste®

petite th aie

dear rele

etd?

ena tent

rere eine

Pad

ted entree’

‘

gay en eee

MREITIO LL baad

regent AY

woe

were ee

ah pews eee

ited eRe

yn patente?

Perera

dua in ty te?

wor te Vie

ee ES PEERS

42 BEES ED PE

aor ha

nee ete

ae a (tea Het te PE

oh ae AN ee

™

pee eS

onsite eUrter

oct ee eine

pew neeees vey’

ire eeu ates Fe Oe eR A

ay cen meee ae ab res ee

ae ~

lett SANT RNY

awe ney

Sait tN omstaere

See

AD ee ot ee

Fe bytn eee

m% Ve

ed Dad

Maine Mee wise hi

Rater tne oem ete Te Peer Twine

Nc tannin eet fervor Ss

Ane eet te NM iat etre NOs Se

<Teen te ™

- Siete ne

odes Sethe

sephora wi acre

Panaied Na ee

aa aN

neath

aygeke uel

preset

Neb ore Wy

ty camer?

ete SN

ee a

me ent

anaeeyty es

demoed wate ¥

Aton

oe as

evn eek

bed

weyers

wn eyes i

vives

ny neh

SPAR PE

weet

we neye we

aye Ne

yon tae

pe tte eed

Pere Ce th akand

ereront he)

ine ee GS

wtewst

ven

ere he “

an aye we Chev ee

te tig NEN ere ewes

ona

tees

ayan ew he

‘at ges wy

waar sense *

an ey err eh ene

ada Wad eed

NOTE heads

pit PR tee

ores

emer toe eeu tnd

are ete eee

ge aya EN

Ave eeEeN

6 POE

weeny

eal

py yt pees ee

ans

oe var het

Fete rua!

peer eey’

wy newess®

agave ee

haan 4

RPT Thi tule

yee

ers

ebbeak a

yun pV

ieee eve

pean tate

pega erent

Fg Belen ete

perth cee’

a yawns

st eene

yn ale

yer dive RSW A

aA ee

Wonca

wed ht

Pedy pst eeee eS

never tes?

wae

yare

went

vena hee

a Fp

wat

ayskety

meee

meas eee

1H GEREN eee tS

’

seawerey tt

tebe ate

wna

nye

rihentas

Voy ineeet welt ee®

“

paaea erene ee a8

ile MRE

Dag stevendet

ga ome TENG Pee

seu yeydi vere dyaee ss

pacar ah sey eee

itet eotdeew

a eee

vhs

waeeesett

Gysse awed sete

parma ee

veke

hae ee ead

ee anarerel

dia tun tee

yrmemewds

syed gees eb Cd

wont

wade

Ewe bh Meas dey wsrs

mehr dE pies byt

ve ay

pera

bei

Tu reyrensete®

Wiens

wevine

“eta Sethe ey

wee’

eee tnehll

ugeaeres®

Tr The

sey Oe

vewaye bee

weverdhaveee

e ayat ak ev aye ®

Terae ed sues y®

vty oy ait aay

cyevewyl fe

Wereeye

eyaves

veegre?

Bre nS

vay hy

panel

Me 7

meer eer tl) bal

ates orate payee ee

PRPS Tikit

WeTwOn Sia

EE CSUN E

He ae ENTE

tommy eee

yeye

Arve

meats

‘

Vosaiewed® phere vg Ny)

Wititoma, Lean HVE OE

ore Deven mani

ome

Tri

Witte eae

PINTO Li mahi

PAC Pu eeaes nes

errs Sead

yorwkytyy #h

wee yk Ere MNT IST LY avi Laan

pum es cp gevircheneedeya yn?

fs f enrari ns

vewtnet

eperyiayere

fener ats Dok

wbenepga ava

ween

meg eee

sew ems

yas er ehin

“

anime

angeced

qnoeee ue

Prerrin ia)

we avendmevsnepoed en cudhe

sewev vee

eres

pasa s sere en eee

yee

bayer

ayeagy cere

Levene kar ds es eVd

TA cheba apn eet

aves eves

ienget wee’

res LL

gbgevbwh edhe

paeate bee OF y

veiw OO

‘ vowel

aye yeh

vay heey hy

ayeredy .

peebe de

wae

ran

pry bee ede Ve WN

svebve’ eprrnné

Eup bare ng ncn eetet

vy veelbeeeh

evaseh ewes

vend

Pri ead

aye

bern

TST) Lhe

so trigty ey UVES

ul tow

woty

aidan ewes a8

eae ak etenth eho bE

‘

pyrene’

wy vewe’®

wubehe

vom

ae seb are

payor eee

patsy attys ol

sy cede ben dhe

Terweenneset seee

TON Lhd cada

pia ateee Oe

Ata LEANER ES

re Thee

SALLE TSS

sph ree b

peer hh tas egg ve ghee MOREE

peapuesueunt ee Saeed TMT Py thn?

wee s

ave eee

pee y

erent gate

sea edo ad NEN ESS iD

Feahe ees

eer

Cyadenn tate yd

ay mene’

vpemcws band dueh yes

Leta er eeenenh ced ee

evebthes t

yews

veh iieaeey ive het

Agee Mee

weld

pen Cyeree E

wader dive

veer

wavered ee ged

nfewel of

sages peethe

webeevreee

“Avene SER aNTS

vane

err

Prato

Py UG YATES OEE

patho Webel ye

Aad yh OLRM aT

vutweerts

ae Pengt e smd ayn Ch by NTE

Sah ibat PAA pt ite

seer ey

yey ah

hats

elev

py ae

gute

Hehe yey a

peste’

Says

ny voy vbw

eave bye yew

atte

yeh aw

wis

eee ebett

‘wy

weigh eo

apr wang bebe’

eee ww

saved

per cuyy cetyl

neh

Me ~

svat cay neve PO ed

bees Wyn Crh

ety ttt

ec wtb anh attey

baa ayes

AAG ta stig BY

Wy bv were

yerede?

auaher

oe iy ator

ay ull ta)

wevetey

vey

Shah itew bell

pe dine’

th Ce eee

ayedwes

RUD AL bTy

OL) ae

byerat at

py iyi

Riva te at EN

cove ANT

why

ath

AVN ih NHN

in) iran

TOO vain"

shel

ate a

fotevil

Reece

anh than oe

ry ai st alt

Nal generar v NY

aed

yew ’

Taduteene ew

grea Nasboal

a aber ance tUtUey nS

eR Tat et

c. ( f

vi s , 7

5 me : ' Lb

f > “i

‘ i ag a 4 1 ox i 3

i ; = ‘5 <

A i

wt t =

5 fms i

cae = > as

~ ‘

j 5 } t 5

{ ‘ ‘

t ¢ } FB gilt ” 2

{ : 4 a

/‘ a

, 4

’ i

“

wy) i

‘ee @

{7 I

Lea

Fi 4

: ts

. et

‘, er

- a

— 4

2 es

i 3

t 7

- aa

i a

’ 2

Misty ernie,

"y 2

ARG

re ;

Pane e

a —_>

(aS

{ me

; ( i

ois {

_ x

)

Tey) 4

( ‘

f 2

Es,

}

‘

, ’

Se es

‘

: +

: :

ree US

‘

} S wv

SO 7K

VOLUME 110 AUGUST 2003 ISSN 0303-2515

oe |

ANNALS

OF THE SOUTH AFRICAN

~MUSEUM

CAPE TOWN

INSTRUCTIONS TO AUTHORS

MATERIAL should be original and not published elsewhere, in whole or in part.

LAYOUT should be as follows:

(a) Centred masthead to consist of: title: informative but concise, without abbreviations and not including the names of new

genera or species; Author’s(s’) name(s); address(es) of author(s) (institution where work was carried out); number of

illustrations and tables; and email address

(b) Abstract of not more than 200 words, intelligible to the reader without reference to the text

(d) Introduction

(e) Subject matter of the paper, divided into sections to correspond with those given in table of contents

(f) Summary (if paper is lengthy)

(g) Acknowledgements

(h) References

(i) | Abbreviations, where these are numerous.

MANUSCRIPT should be typed, double spaced with adequate margins. Four copies should be provided. First lines of

paragraphs should be indented. Tables and a list of figure captions should be typed separately, their positions indicated

in the text. All pages should be numbered consecutively.

Major headings of the paper are centred capitals; first subheadings are centred small capitals; second subheadings

are shouldered small capitals; third subheadings are shouldered italics; fourth subheadings are indented, shouldered

italics. Further subdivisions should be avoided, as also enumeration (never roman numerals) of headings and

abbreviations. Footnotes should be avoided unless they are short and essential. All generic and specific names should

be underlined or italicized.

ILLUSTRATIONS should be reducible to a size not exceeding 12.5 18.5 cm (19.5 cm including caption); the

reduction or enlargement required should be indicated in pencil on the reverse of the figure; originals larger than

36 48cm should not be submitted; photographs should be rectangular in shape and final size. The size of illustrated

objects may be indicated by a metric scale on the figure (if appropriate), or the enlargement or reduction should be

given in the caption; if the latter, then the final reduction or enlargement should be taken into consideration.

All illustrations, whether line drawings or photographs, should be termed figures (plates are not printed; half-tones

will appear in their proper place in the text) and numbered in a single series. Items of composite figures should be

designated by capital letters; labelling on all figures should be non-serif lettering (e.g. Helvetica, Univers) of uniform

style, in lower-case whenever possible, and of appropriate size taking into account the final size. The number of the

figure should be lightly marked in pencil on the back of each illustration, together with an indication of the desired

reduction or enlargement.

REFERENCES cited in text and synonymies should all be included in the list at the end of the paper, using the Harvard

System (ibid., idem, loc. cit., op. cit. are not acceptable):

(a) Author’s name and year of publication given in text, e.g.:

‘Smith (1969) described

‘Smith (1969: 36, fig. 16) described ...’

“As described (Smith 1969a, 19696; Jones 1971)’

‘As described (Haughton & Broom 1927)...’

‘As described (Haughton et al. 1927) ...’

NOTE: no comma separating name and year; pagination indicated by colon, not p. (except in synonymies, see

example 2); names of joint authors connected by ampersand; ef a/. in text for more than two joint authors, but names of all

authors given in list of references.

(b) Full references at the end of the paper, arranged alphabetically by names, chronologically within each name, with

suffixes a, b, etc., to the year for more than one paper by the same author in that year, e.g. Smith (1969a, 19695) and not

Smith (1969, 1969a).

For books give title in italics, edition, volume number, place of publication, publisher.

For journal articles give title of article, title of journal in italics (according to the World list of scientific periodicals.

4th ed. London: Butterworths, 1963), series in parentheses, volume number, part number in parentheses (if pagination

discontinuous), pagination (first and last pages of article).

Examples (note capitalization and punctuation)

BULLOUGH, W. S. 1960. Practical invertebrate anatomy. 2nd ed. London: Macmillan.

FISCHER, P. H. 1948. Données sur la résistance et de la vitalité des mollusques. Journal de conchyliologie 88:

100-140.

FISCHER, P. H., DUVAL, M. & RAFFY, A. 1933. Etudes sur les échanges respiratoires des littorines. Archives de

zoologie expérimentale et générale 74: 627-634.

KOHN, A. J. 1960a. Ecological notes on Conus (Mollusca: Gastropoda) in the Trincomalee region of Ceylon. Annals

and Magazine of Natural History (13) 2: 309-320.

KOHN, A. J. 19604, Spawning behaviour, egg masses and larval development in Conus from the Indian Ocean. Bulletin

of the Bingham Oceanographic Collection, Yale University 17 (4): 1-51.

THIELE, J. 1910. Mollusca. B. Polyplacophora, Gastropoda marina, Bivalvia. In: SCHULTZE, L. Zoologische und

anthropologische Ergebnisse einer Forschungreise im westlichen und zentralen Stid Afrika ausgefiihrt in den Jahren

1903-1905 4 (15). Denkschriften der medizinisch-naturwissenschaftlichen Gesellschaft zu Jena 16: 269-270.

ANNALS OF THE ANNALE VAN DIE

SOUTH AFRICAN MUSEUM SUID-AFRIKAANSE MUSEUM

VOLUME 110 BAND 110

ANNALS OF THE SOUTH AFRICAN MUSEUM

ANNALE VAN DIE SUID-AFRIKAANSE MUSEUM

VOLUME 110 BAND

AUGUST 2003 AUGUSTUS

TYPBSET BYOUSERERIENDIEYS CAPE TOWN

PRINTED AND BOUND BY MILLS LITHO, NYMAN STREET, MAITLAND

LIST OF CONTENTS

GOWER, DAVID JOHN

Osteology of the early archosaurian reptile Erythrosuchus africanus Broom ..........

COOPER, MICHAEL ROBERT

Upper Cretaceous (Turonian—Coniacian) ammonites from

S2ORNiColaUey MOO ldmena tea Sremt CR oe ee a ee Se 89

COOPER, MICHAEL ROBERT

Stratigraphy and palaeontology of the upper Cretaceous (Santonian)

Bubastonmationvay sao NicolausAmeolay..22 . 4 5). = 2k tn ee ee et 147

KLINGER, HERBERT CHRISTIAN & KENNEDY, WILLIAM JAMES

Observations on the systematics, geographic and stratigraphic distribution

and origin of Diplomoceras cylindraceum (Defrance, 1816)

(eepnalonodasAmimonoded)Ai65.. = Oe oe me Bk Se ee ia

KLINGER, HERBERT CHRISTIAN & KENNEDY, WILLIAM JAMES

Observations on Pseudoxybeloceras matsumotoi Collignon, 1965

(Cephalopoda: Ammonoidea). Ontogeny, shell structure, differential

PeeSeVANlOnlandninlraSpPeCINC VanlallOM sa. aw. ok Po ee ee 199

KLINGER, HERBERT CHRISTIAN & KENNEDY, WILLIAM JAMES

Cretaceous faunas from Zululand and Natal, South Africa. The ammonite families

Nostoceratidae Hyatt, 1894 and Diplomoceratidae Spath,1926............. YIN,

Volume 110 is complete in 6 parts.

EE.

gril

;

ere @ an plateptineey i

ANNALS OF THE SOUTH AFRICAN MUSEUM

ANNALE VAN DIE SUID-AFRIKAANSE MUSEUM

Volume 110 Band

August 2003 Augustus

Part l Deel

OSTEOLOGY OF THE EARLY ARCHOSAURIAN REPTILE

ERYTHROSUCHUS AFRICANUS BROOM

DAVID JOHN GOWER

The South African Museum forms part of Iziko Museums of Cape Town

The Annals of the South African Museum publishes original research articles, revisions and review

articles in natural history (palaeontology, geology, entomology, herpetology, ornithology,

mammalogy, and marine and freshwater biology), social history (anthropology, archaeology and

history), and art.

In order to be considered for publication, manuscripts should deal, at least in part, with material

from the collections of Iziko Museums of Cape Town. Other contributions are also considered

provided at least one of the authors is a staff member or affiliate of the Museum. In the case of

taxonomic work, descriptions of new species not already part of the Museum’s collections, the

holotype and, if possible, part of the paratype series must be deposited in the South African

Museum. Authors whose contributions do not meet with these criteria should contact the Editorial

Board prior to final preparation and submission of their manuscript.

All articles are refereed by three referees of international standing. Each paper accepted is

published as a separate part. We endeavour to publish a minimum of four issues per annum at

quarterly intervals, as material becomes available; parts are priced individually and different

volumes do not necessarily contain a standard number of parts.

Editorial Board

Prof. H. J. Deacon Dr K. Skawran Prof. A. Chinsamy-Turan

Prof. C. L. Griffiths Prof. B. Rubidge Dr H. C. Klinger

Dr S. van Noort Ms M. Rall

Ms E. Louw (editor)

ANNALS OF THE SOUTH AFRICAN MUSEUM

Publisher: South African Museum, P.O. Box 61, Cape Town, 8000, South Africa

Please direct enquiries (including copyright) and manuscripts to the Editor.

Please direct orders and subscriptions to the Editor.

BACK COPIES

Orders for back copies of the journal are welcome. For a full list of papers published

since 1898, please write to the above address or visit our web-site:

http://www.museums.org.za/iziko/sam

OUT OF PRINT

h, AU-3, 59), 302, 2S, 7B, eg), AA), SCS, 1-2), G2, epi),

HOA), SOU D, 7), WOG-D), MGE2, 5, 7, esos), WA), 1545).

24(2-3, 5), 27, 30(5), 31(1—3), 32(5), 33, 36(2), 43(1), 44(7), 45(1), 49,

67(5, 11), 77(7), 84(2), 93(3), 100(1)

ISBN 0 86813 183 0

DTP by User Friendly, Cape Town

Printed in South Africa by Mills Litho, Maitland, Cape Town

OSTEOLOGY OF THE EARLY ARCHOSAURIAN REPTILE

ERYTHROSUCHUS AFRICANUS BROOM

DAVID JOHN GOWER

Department of Zoology, The Natural History Museum, Cromwell Road,

London SW7 SBD, U.K.

and

Department of Earth Sciences, University of Bristol, Queens Road,

Bristol BS8 IRJ, U.K.

(With 37 figures and 2 tables)

[MS submitted May 1996]

LMS accepted June 2001]

ABSTRACT

Erythrosuchus africanus Broom (Archosauria, Erythrosuchidae) is an early, non-crown-group

archosaurian reptile known exclusively from the Lower—Middle Triassic Cynognathus Assemblage

Zone of the South African Karoo Basin. A detailed redescription of the osteology, excluding that of the

braincase and tarsus, 1s presented, based on examination of nearly all known material. Several skull and

mandibular elements are described for the first time. Aspects of the interpreted and documented

osteology of particular interest include the presence of three-headed pectoral ribs, an antorbital fossa,

osteoderms, and possibly pneumatized neural arches. Palatal teeth are documented in the Russian

erythrosuchid Garjainia prima. New skeletal reconstructions of E. africanus are presented. Many skull

elements have joint surfaces that form potentially movable articulations with other elements, but

consideration of the adult cranium and mandible as whole units shows that they were not kinetic to any

notable extent. The main variations in morphology among known specimens of E. africanus are

summarized. Convincing intrinsic evidence for the recognition of more than a single species of

Erythrosuchus 1s lacking. Among erythrosuchids, the distribution of apparently derived osteological

features supports evidence from braincase osteology that has been interpreted as indicating that

E. africanus and the Chinese Shansisuchus are more closely related to one another than either taxon is to

Garjainia prima, although a new explicit analysis of phylogeny has yet to be performed.

Ann. S. Afr. Mus. 110 (1), 2003: 1-88, 37 figs, 2 tables, appendix.

ANNALS OF THE SOUTH AFRICAN MUSEUM

Figure |

Erythrosuchus africanus. Restoration of skull and mandible, based largely on BPI 5207. Text should be

consulted for information on variation among specimens. A. Left lateral view. B. Dorsal view.

C. Occipital view.

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 3

CONTENTS

PAGE

LAMPMO GUN CLLOM: <cseetascccaeadacn: cca Ree ERRE EMOREE ee teats: on eet saSnsvie nc hope aoaasacsneer ee yeh retaee heiann ride tacpeeee eae see 5

General ic ONminenisy a set en eer eee ne ree eats os Ss wccsam ew enau danas’ dcdpunte estes nottntnee sas coueeyainniesen «dias ane smeteeeey 5

VEY OSUEGIIIISEC IT CONUS A eetzt™ iteess EPOPRR ES 5c: cd wonscsydnse cs vas «tea consnsteeiseseaa tM taes.¥idssnenenegertousie aoctaes @)

GeO OSCARS LUN Orme RAM ere MR ee each hb dar dc uNlowdlseedn nsbaldnwa cd sdbantosdndddtonns wooed snes doctipeniendevaces> JI

IV Hata SeCIN CIMT LINO CLS eeteeteee sc. emer dass, cde bet eAGes ois uuieanepannataosie dePaate dee taeaai oak fy fame en seeameems avi teoilee 9

MIN ce ere ee ee cere eer tie, ASRS es, «0s csacaaie cdnpsldgadedeacs Riadet saadsveusacsestuvaereen cvleeess 1]

AO aT) SiS Pee ee ier shee Lee Mee ge.) Pee diotaviha ssicdhaaniswasdud vdtweet eototavsnpisstvacen seWertvaFhearsenacnss 1]

H.OIGIRIDE checcoocceatdesedono so7daboSeBacooeclacce athe ets iSees hc he et ihe ie nea ee ee 13

IL El testa ch lene eet Reenter ce Nx SA Meaty A Ra 52 us hvcocaesoaiatieck'c oc ouueapaglssvavsocteseetYoetesvarentosseboncrteens 13

FRU ITT eee es Is ss ENR se ene eRe AID Meeth 8 fac sa assltiiaelesenccmsoegacliont apeeclacomatwel you skintecon ieee decews 13

WES Chip il OMemrt atc ncste ecoes:- -vecaee seth postht apse raveturbeeseseszeancstsessstasranesnsaovorseyadencesrordewcarcsraqysucebavesrestnaeareree> 15

Salil ee: <r eR cs ON NU nee gO es Sos YE bL ewan Nia v SovaeUgbonbnausesuduuicemapheleel yertOEAls ative anes 15

Dermalibones-otithe SkullitO ois sex... eee seen eee saa oe has (edi das Puaenen tN tages scaasscosnsentnceses LS

eee IN OUD eee Morn et cc a Ra eh reais chcva's om MAREE Ct ASLAE «cna anne ce tete tens <onbinn cis sSagekn iste seSehatesteas 25

IN teal eee ree Mee Ae see ee Se clas ge maida wane cihy'ssins avqwibaileds sued dios aude gnc soimacste umn tactweansassen 3]

JD) aie fslils] Oot Mmmm eee te ete SOR aoe re ch coche candi an'idlal ecnsiedaas se Gadloaxousstapsmntunch ce aos phbamosdscrnapecs 36

PSHE TECHN COLUM Ene nerene in eee ee cartes eee ste SES AS tr. 2A sacs ja cog\stedieaalsegSouesbusoenen doacestew cee aerateeeee seats 3)

\W CIC ONENS BVDG! THOS cola tech soph ck Acie eRece nee LL Eee an een RRO BAEEA eCn Sane Sen ee aI

Iintencemiraran dana tinal leanemestarmen an tic curs.) 6sscss00%uasenons-cocsacceucent asaaaacesioss a cneemrestodererezes 53

NO DSDG NCTM ETE Sl SSOOETT IS aso caees gence scee aac cose Oe Rae ee eee ee ee ap)

IL AIAG OVEMEVALAAONA WIE TUL TTO) OY SNY Magen ccheac coe scReRen at cote eee ee eee Meena coe eaceeerne a)

Fe ce tell A) CHIMCAM INIA ees eee eR sc MMM 2201 ciaulnsten « acces teedebandsaactouwncte Mes acadicre canons 55)

|PEINAIG (ATMS GiTeV6 WTS) Supe cece neies Sea: so 7 kao eee geen ce er cer Sener meer eee ae 61

Geis iced cere eee eee AM, «AM NINN Sen aRealRee eave nlltdte Sica th wna Rieeecedsiaastes <n uhh pamaiess Meeass 69

OSS OC STAD ee airs att EO Roc Ba eB coee Se APR A Re Ce Oa ee Oe eRe 69

LTT OINCEAT OOS encoabiieacteeres Sees odcossb esc bes tone Ae SCUC RAM EEE OT ee ene Re ne oe Pee eee 71

SIREN ial TACOS TAC TO Sia ae ee ae Se ae ee eee ee ee Ae qi

Gremialeanne pana cil ul cite KAM SSH 33.25 ecavehoadesoseseoncteson s<deansdemeeeecotous <del nsaeeeet cece a tater es SReeeaeaaas omer eaat |

BR Arse OTN ON rere ee sae ee a ce ast ct ON cela ats dena ninc die Mic Nein. xc cok ca MMMM ONS saeh wana Mawes aah eben fat YZ

PLT ODS Roddoocdbooc ote etre wo coe eee 55 8 Ro SES) 74

FXG KMONVAC OS C10 CIN LSM teem ny eerie MR ie Mette! Pear a eels nccai~ fave anecseasssbabapadanss Tecensesestehs soswoeoResvt-ndvnss WS

IRSITSIRETAOSS: sesh o SIS UR REO ABRs SR RSE eM eer Aa OE ee Peete ee, erm - nee WS

/A\| DIDIER OLAS, Bae tee tee se Bese cee oe ee Re ee i ee NS ne Oe ee eee 80

AS CUCL OTS eee eee ren eee 2a ssh ssuies oanianaglGudyerasadnnna, Sette deve sie tecemenaniee Comme me manatee aces 2. 80

INTC ap OL) ay aoe a ee ee ns ec sre I sao anne SUG phd ie RA aceon cece SE OM a ais 80

PSO OSTINGIE Os. asapccas anes soc eee eC eNUASaO ESE GEER MERE te eo eo a Pes ce eee eee eee 83

4 ANNALS OF THE SOUTH AFRICAN MUSEUM

Figure 2A

Erythrosuchus africanus. Skull and mandible of BPI 5207. Right lateral view.

Figure 2B

Erythrosuchus africanus. Skull and mandible of BPI 5207. Right lateral view.

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM J

INTRODUCTION

GENERAL COMMENTS

Archosauria is a major clade of diapsids that consists of birds, crocodilians, dinosaurs,

pterosaurs and their nearest fossil relatives. Archosaurs dominated every terrestrial and

aerial large vertebrate niche for most of the Mesozoic. Recent interest in the pattern of

their radiation has focused upon the application of a cladistic methodology in the

inference of phylogenetic relationships, resulting in a number of major recent publications

(Gauthier 1986; Benton & Clark 1988; Sereno & Arcucci 1990; Sereno 1991; Parrish

1993; Juul 1994; Bennett 1996; Benton 1999).

Whereas these studies contain a certain amount of agreement on the interrelationships

of some of the main archosaurian groups (Gower & Wilkinson 1996), they are to some

extent based on differing approaches to the use of the same morphological information

available from the existing descriptive literature. Over the last decade the research effort

directed toward reassessing basal archosaur morphology and producing detailed

osteological descriptions pales in comparison with work conducted within the

phylogenetic research programme. This is also evident in the fact that the cladistic

analyses of archosaur relationships have focused thus far largely on the broader question

of the relationships between, rather than within, the major groups—their monophyly

largely being accepted a priori.

It could be argued that no detailed, complete osteological descriptions of any early

archosaur currently exist. Indeed, since Charig & Reig (1970: 140) reported that ‘the only

well known [early archosaur] genera are Chasmatosaurus, Erythrosuchus and Shansisuchus,

and even of those our knowledge is far from complete’, there has been only a single and

relatively brief reassessment (Cruickshank 1972) of the osteology of any adequately

represented early archosaur. Despite this, the existing descriptions remain the major

source of information used in the large number of recent cladistic analyses of basal

archosaurs. It is the aim of this paper to make a step towards redressing the morphology—

phylogenetics imbalance, by presenting a detailed revision of the osteology of

Erythrosuchus africanus.

The taxon Archosauria is used throughout in its traditional concept (see Juul 1994).

The restricted members of the Archosauria of Gauthier (1986; = Avesuchia Benton, 1999)

are referred to as “crown-group archosaurs’ (= avesuchians of Benton 1999).

ERYTHROSUCHUS AFRICANUS

Erythrosuchus africanus was named and preliminarily diagnosed by Broom in 1905 on

the basis of a single, incomplete post-cranial specimen (SAM—905). This was followed by

a fuller description of the holotype in which Broom (1906) also referred E. africanus to

the Phytosauria. A much more complete specimen, BMNH R3592, was the focus of a

more detailed monograph by Huene (1911), who considered E. africanus to be a

representative of a new reptilian order, the Pelycosimia, closely allied to the Pelycosauria.

6 ANNALS OF THE SOUTH AFRICAN MUSEUM

100 mm

Figure 2C & D

Erythrosuchus africanus. Skull and mandible of BPI 5207. C. Left lateral view. D. Dorsal view.

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 7

Huene recognized that some material referred by Seeley (1894) to Euskelosaurus brownii,

actually belonged to E. africanus. Some of the cranial material of BMNH R3592 is

incomplete or missing, whereas some of the preserved elements were ignored or

misidentified by Huene (e.g. laterosphenoids and palatine respectively). The

informativeness of parts of Huene’s description are perhaps further clouded by his belief

that Erythrosuchus has affinities with the Pelycosauria.

Watson (1917) placed E. africanus in his newly erected family, Erythrosuchidae. Later

systematic studies have consistently placed Erythrosuchus within the Archosauria in the

order Thecodontia and the suborder Proterosuchia (e.g. Charig & Sues 1976). These last

two taxa are commonly considered to be paraphyletic grades, and the results of cladistic

analyses have placed a monophyletic Erythrosuchidae outside the archosaur crown group

(e.g. Benton & Clark 1988; Sereno & Arcucci 1990; Sereno 1991; Parrish 1992, 1993;

Bennett 1996; Gower & Sennikov 1997).

Further descriptive accounts of Erythrosuchus africanus, and particularly of the tarsus

and braincase, have been presented by Huene (1920), Hughes (1963), Cruickshank

(1978), Gower & Sennikov (1996a) and Gower (1996, 1997). Parrish (1992, fig. 6)

presented a drawing of the skull of BPI 5207, but many of the sutural patterns depicted are

at variance with the observations made during the current study (compare with Figures

1—2 here). There have been no substantial reassessments of most of the osteology of this

important taxon since the work of Broom and Huene.

The aim of this study is to revise and correct descriptions that exist for those parts of the

skeleton previously studied but not described in detail, and to cover in detail the numerous

parts never previously described—in particular much of the skull and mandible. As a

result of the rarity of detailed descriptions and sub-familial phylogenetic analyses of early

archosaurs, it is not possible in most cases to fully assess the distribution of the features

described here. Where possible, considerations of the distribution of features are given by

means of comparative data.

Description of the problematic tarsal material, of a cast of the endocranial cavity, and

of the detailed structure of the braincase is presented elsewhere (Gower 1996; Gower &

Sennikov 1996a; Gower 1997).

GEOLOGICAL SETTING

The Karoo basin of southern Africa is well known for its extensive complex of

mudstones and sandstones, deposited from the Permo-Carboniferous to the early Jurassic

(300-190 Ma). Much of the impressive diversity of Mesozoic vertebrate remains to have

been documented are known from the fluvio-lacustrine succession of sediments of the

Beaufort Group (late Permian to early Triassic) of South Africa. The upper part of the

Beaufort Group is represented by the Cynognathus Assemblage Zone, and it is from this

zone that perhaps all specimens of Erythrosuchus africanus have been collected. The only

potential exceptions would seem to be erythrosuchid specimens from the equivalently-

aged Omingonde Formation of Namibia (Pickford 1995).

The Cynognathus Assemblage Zone has previously been equated with the upper part

ANNALS OF THE SOUTH AFRICAN MUSEUM

[ju

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM gy

of the Lower Triassic (e.g. Charig & Sues 1976; Anderson & Cruickshank 1978; Sun

1980), but the most recent studies (e.g. Ochev & Shishkin 1988; Shubin & Sues 1991;

Shishkin & Welman 1994; Shishkin & Ochev 1995) suggest that its vertebrate fauna is

instead consistent with a lowermost Middle Triassic age. Sediments assigned to the

Cynognathus Assemblage Zone in South Africa are best exposed in the south-western

Free State and northern part of the extreme Eastern Cape Province (Kitching 1977).

Recently, Welman ef al. (1991) have also discovered vertebrate-bearing Cynognathus

Assemblage Zone deposits in the north-eastern Free State. Erythrosuchus africanus

specimens have been collected from a number of the best-known localities (Kitching

1977). The holotype originates from Oorlogsfontein, Aliwal North, whereas the other

most important specimens were discovered in localities near Burgersdorp

(BMNH_ R3592, BPI 2096—Geluk; NM QS1473—Winaarsbaken) or Rouxville

(BPI 4680, 5207—Betjeskraal; BPI 3893—-Lemoenfontein), all in the Free State. The

seven specimens listed above form the basis for the majority of current knowledge of the

morphology of Erythrosuchus africanus. Many of the approximately 60 known

specimens (see Appendix I) consist of disarticulated, isolated and/or poorly preserved

finds.

The Cynognathus Assemblage Zone vertebrate fauna contains many synapsids (e.g.

Cynognathus, Diademodon, Trirachodon, Bauria, Kannemeyeria), at least two

archosaurs (Erythrosuchus, Euparkeria), rnynchosaurs (Howesia, Mesosuchus), fish, and

capitosaurid amphibians (Kitching 1977; Welman et a/. 1991). There is generally a lack of

detailed records of the preservation of individual specimens of Erythrosuchus africanus

that might be taphonomically informative. However, a photograph of BMNH R3592 prior

to preparation, shows that this incomplete specimen (missing several elements including

some from the skull, the left forelimb, right forelimb epipodials, scapulae, intercentra) is

disarticulated apart from the caudal vertebrae and firmly sutured elements of the skull roof

and part of the braincase. The preserved elements form a concentrated jumble of bones in

a flat and tightly-packed ‘conglomerate’, approximately 1.5 x 1 xX 0.15 m in size. This

assemblage is perhaps indicative of fluvial winnowing, and is therefore consistent with

the interpretation of detailed studies of Karoo vertebrate taphonomy (e.g. Smith 1993),

that the fossiliferous deposits are channel/overbank and adjacent flood plain in their

origin.

MATERIALS AND METHODS

A full list of Erythrosuchus africanus material is presented in Appendix I. A small

amount of mechanical preparation (vibrotool) was undertaken on BPI 4526. Some

Specimens, but most notably BPI 3893, will possibly yield new information (e.g. on the

palate) when they are fully prepared. Most of the observation of specimens for this study

took place in the early 1990s. Further preparation and/or collection of material may have

taken place since then.

ANNALS OF THE SOUTH AFRICAN MUSEUM

‘Q[BIS SUIS 0} JOU IB SUOT}DOS “DOT IO1I9}SOd JO MIA JOLIOJUY “4 “YOo]q

[eUId JO MOIA IOLID1SOg “FY YOO] [eUSO JO MIIA IOLIOUY “ “€68E Idd JO V[qipuew pur [[nys poredaiduyg ‘snuvoiufy snyonsoayeugq

A a ‘de ons

\\— e Jul

a |e EB

9 BS

48) jd

ee)

1d [ j

Lt,

id dyad

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM Il

SYSTEMATICS

DIAPSIDA Osborn, 1903

ARCHOSAUROMORPHA Huene, 1946

ARCHOSAURIA Cope, 1869

Family Erythrosuchidae Watson, 1917

Genus Erythrosuchus Broom, 1905

Erythrosuchus africanus Broom, 1905

1889 Theriodont: Lydekker, pp. 572-573, pl. 54.

1890 Genus non det.: Lydekker, pp. 96-98.

1894 Euskelosaurus brownii Huxley: Seeley, pp. 335-340, figs 6—7.

1905 Erythrosuchus africanus Broom, pp. 336-337.

1906 Erythrosuchus africanus Broom: Broom, pp. 187—195, pl. 4.

QUEM Erythrosuchus africanus Broom: Huene, pp. 3—25, pls 1-11.

TS Erythrosuchus africanus Broom: Broom, p. 160.

1915 Erythrosuchus africanus Broom: Huene, p. 495, fig. 16.

1920 Erythrosuchus africanus Broom: Huene, p. 489, fig. 51.

1926 Erythrosuchus africanus Broom: Huene, pp. 44-45, figs 6—7.

IS Erythrosuchus africanus Broom: Brink, pp. 146—148, fig. 2.

1963 Erythrosuchus Broom: Hughes, pp. 227—230, figs 1-2, 4—6.

1970 Erythrosuchus africanus Broom: Charig & Reig, pp. 134, 156—160, fig. 3.

DIS Erythrosuchus africanus Broom: Ochey, p. 102.

1976 Erythrosuchus africanus Broom: Charig & Sues, pp. 28, 30.

1978 Erythrosuchus africanus Broom: Cruickshank, pp. 161—176, fig. 1, pls 1-13.

1981 Erythrosuchus Broom: Brinkman, pp. 18—20, fig. 12A—B.

92 Erythrosuchus africanus Broom: Parrish, pp. 94-101, figs 2, 6.

1994 Erythrosuchus africanus Broom: Juul, pp. 3-4, 6, 12.

1996 Erythrosuchus africanus Broom: Gower, pp. 349-358, figs 2-6.

1996a = Erythrosuchus africanus Broom: Gower & Sennikov, pp. 581-583, figs 1-2.

19966 ~~ Erythrosuchus Broom: Gower & Sennikov, pp. 896—900, table 1.

1997 Erythrosuchus africanus Broom: Gower, pp. 557-573, figs 1-11.

1997 Erythrosuchus africanus Broom: Gower & Sennikov, table 2.

1997 Erythrosuchus africanus Broom: Witmer, pp. 12, 52.

2001 Erythrosuchus africanus Broom: Gower, pp. 120-121, fig. 2.

Diagnosis

Large erythrosuchid; skull and total snout—tail length possibly up to 1 m and 5 m

respectively. Skull tall and narrow, with antorbital fenestra and fossa. Fossa surrounds

antorbital fenestra. Ascending process of maxilla raised laterally and separated from

posterodorsal process of premaxilla by ventral flange of nasal. Jugal excluded from

antorbital fenestra by maxilla-lacrimal contact. Frontals L-shaped. Prefrontals triangular

with caniculae on dorsal surface. Fossa present in pineal region. Postparietal forms

ANNALS OF THE SOUTH AFRICAN MUSEUM

C6SEN HNN JO se [[xeutoid Jo smorA [eUDA puk [eso *D ‘76SEM HNWA

JO ov[[rxeuioid JO SMOIA JeIOVeT “{ “O7Sp Idd “BI[rxeuosd yYyS11 posedosd Ayoyojduroour Jo MIA yeIO\eT] “y ‘SNUDILA{D SNYINSOLYIAAT

p onsty

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 13

pyramidal occipital peg. Quadratojugal very nearly or completely excluded from lateral

temporal fenestra by squamosal-jugal contact. Posterior process of postorbital with

incised groove. Squamosal with pleat in posterior margin of descending ramus. Foramen

absent between quadrate and quadratojugal. Post-temporal fenestrae no more than narrow

slits. Transverse processes of parietal with posteromedial tubercles. Palatal teeth absent

on pterygoid, uncertain on palatine and vomer.

Supraoccipital excluded from foramen magnum. Basioccipital excluded from foramen

magnum and floor of endocranial cavity. Basisphenoid midline exposure absent on floor

of endocranial cavity. Ventral ramus of opisthotic recessed within stapedial groove.

Stapedial groove with small bulge. Medial wall of otic capsule not fully ossified. Metotic

foramen undivided. Lagenar region not differentiated or elongated. Basisphenoid inter-

tuberal plate small. Laterosphenoid short and thick, with an anterodorsal channel.

Dentary expanded anteriorly and with three tapering posterior processes.

Retroarticular region of jaw short, with low ridge on posterodorsal surface. Five

premaxillary teeth; approximately 11 maxillary and 13 dentary teeth.

Estimated 25 presacral, two sacral, and at least 35 caudal vertebrae. All vertebrae short.

Separate intercentra present (probably throughout precaudal column). Dorsal neural

arches pierced by subdivided foramina, perhaps pneumatic in nature. Three-headed ribs

present in pectoral region. Scapula large and coracoid relatively small. Humerus robust,

with quadrangular deltopectoral crest. Femur with intertrochanteric fossa and prominent

ventral trochanter positioned slightly away from proximal end. All limb bones with

rugose/unfinished articular ends. Astragalus spherical. Calcaneum plate-like and with

laterally directed tuber. Fourth distal tarsal with ventral peg. First two distal tarsals and

centrale absent. Metatarsal III the longest. Osteoderms present.

Holotype

SAM-905 in the South African Museum, Cape Town. Incomplete postcranial skeleton

from the locality of Oorlogsfontein, Kraai River, a few miles east of Aliwal North, Eastern

Cape Province, South Africa—Cynognathus Assemblage Zone, Upper Beaufort series,

Karoo system; upper part of the Lower Triassic or lower part of the Middle Triassic.

Material

A list of current material referred to Erythrosuchus africanus 1s given in Appendix I.

Remarks

Tatarinov (1961) synonymized the Russian genera Vjushkovia, Garjainia, Dongusia,

and the Argentinian Cuyosuchus with Erythrosuchus, but maintained distinctions

between respective species. These generic synonyms were rejected by Young (1964),

Charig & Reig (1970) and Charig & Sues (1976) and this view is accepted here. (All

except the Argentinian material has been examined.) Sennikov rejected the congeneric

status of E. africanus and E. magnus Ochev, 1980, and established the genus Uralosaurus

for the latter (Gower & Sennikov 2000). The taxonomy of Erythrosuchus is discussed

further below.

ANNALS OF THE SOUTH AFRICAN MUSEUM

"SMOIA [PIPOU

pur [eso}e] Ul OZ Idd JO Ll[EXeU IYSHY “ “SMOIA [eIPOU puL JOLIOJUR “TeIOJL] UL 8601 M-WVS JO PI] xeul yor “y ‘snuvotufo snyonsosyjcugq

¢ INS

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 15

DESCRIPTION

SKULL (for restoration, see Fig. 1)

The skull of Erythrosuchus africanus bears many features common to early,

presumably carnivorous, archosaurs: it is relatively tall and narrow, and possesses an

antorbital fenestra and fossa and recurved, serrated teeth. Notable cranial kinesis is absent

(see discussion below), and ‘articulation’ is used throughout to describe contact without

implying that a movable joint was present between two or more articulating elements.

Dermal bones of the skull roof

The premaxilla (Figs 2—4) is a short and narrow bone with two posteriorly directed

processes attaching it to the nasal and maxilla. A slender anterodorsal process extends

back to articulate with a groove on the dorsal surface of the nasal. Just behind the medial

edge of the base of this process is a foramen interpreted as probably transmitting the

medial ethmoidal nerve. Contact with the maxilla is achieved with a long and tapering,

posterodorsally directed process. The dorsal edge of this process forms the posteroventral

border of the external naris, the ventral edge contacts the front of the maxilla, and the

medial face of the posterior part of the process articulates with a shallow and closely

matching depression on the lateral flange of the nasal. Preparation of BPI 4526 revealed

the presence of a small posteriorly directed peg near the base of this process (Fig. 4A).

This peg, probably eroded away in BMNH R3592 and not visible in other specimens,

articulates with a pit on the anterior edge of the maxilla. A similar premaxillary peg is

present in this position in Shansisuchus kuyeheensis (Cheng, 1980).

Medially there is a short and slender palatal process. The area of symphysis between

the premaxillae covers a large anterodorsal part of their medial surface. Each premaxilla

holds five teeth.

The maxilla (Figs 2, 5, 6) is a long, narrow element that bears most of the upper jaw

dentition and forms the anterior and ventral border of the oval-shaped antorbital fenestra.

Anteriorly it articulates with the lacrimal, nasal, and premaxilla, whereas posteriorly it

firmly interlocks with the jugal and contacts the lacrimal.

The maxilla articulates with both the nasal and the anterior of the lacrimal by means of

a posterodorsally directed ascending process. The anterior edge of this process is grooved

to accommodate the posteroventral edge of the anterolateral flange of the nasal. The base

of the ascending process is raised to form a lateral ridge. Behind this, the posteroventral

edge of the process is thin and inset, and it extends posteriorly to articulate with a ventral

groove on the nasal before terminating in a depression on the lateral surface of the anterior

ramus of the lacrimal. As a result of this arrangement, the antorbital fenestra is

countersunk within a larger lateral depression—the antorbital fossa.

The anterior margin of the maxilla bears a broad, shallow groove that articulates with

the premaxilla. Situated within this groove is a posteriorly directed pit that accepts the peg

on the premaxilla. This pit is clearly seen in SAM—K1098 (Fig. 5A) and in the less well-

preserved maxilla of BMNH R3592. The present study disagrees with Juul’s (1994: 12)

ANNALS OF THE SOUTH AFRICAN MUSEUM

“SMOIA [RIPOU

pur [e1aqe] Ul Z76SEM HNIN JO B[Pxeus yo “_ “SMOIA JesIOp pue [eps “[e1oqL] Ul GZS Idd JO PI[XeU sry YW ‘snuvoLifo snyonsosyjAsy

9 wINnsIy

jed

seul

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 7.

identification in BPI 5207 of a ‘dorsoventrally elongated fenestra between the premaxilla and

maxilla’, comparable to openings in this region in other erythrosuchids and some

crown-group archosaurs. No fenestra could be located on the largely undisturbed right or the

somewhat flattened left side of BPI 5207, and there is no evidence for the presence of an

elongated fenestra in other (albeit mostly disarticulated) specimens. Openings in this region of

the skulls of archosaurs come in a diversity of forms. Among those taxa discussed by Juul

(1994), for example, the openings in Shansisuchus and Chalishevia are large circular fenestrae

lying between premaxilla, maxilla, and nasal, with a neighbouring fossa in the latter element

(Gower & Sennikov 2000). This is quite different to the similarly positioned openings in the

dinosaurian and rauisuchian taxa that Juul mentioned. In addition to requiring more precise

information on the form of any foramina or fenestrae in this region, the function and potential

homology of these features is badly in need of reinvestigation (Gower 2000).

The ventral edge of the maxilla is sigmoidally curved in lateral view and this

accentuates the wide notch between the ventral edges of the premaxilla and maxilla. The

maxilla tapers posteriorly and meets the jugal. Posterodorsally, the ventral arm of the

lacrimal also contacts the maxilla. Details of this articulation are not known but it

definitely excludes the jugal from the border of the antorbital fenestra.

A feature observed on BMNH R3592 is the presence of an incomplete, small dorsal

projection that notches the ventral border of the antorbital fenestra (Fig. 6B). This is

perhaps superficially similar to the condition in Euparkeria capensis as reconstructed by

Ewer (1965, fig. 2). The presence of this projection is also suggested by a broken surface

in SAM-K 1098, but it 1s apparently absent or not preserved in other specimens.

Medially, the palatal process is positioned far anteriorly. Posteriorly it is stout and

firmly fused to the medial wall, whereas anteriorly it is much thinner dorsoventrally and

slopes ventromedially to form an overhang (Fig. 5B). It is possible that the opposite

palatal processes of the maxillae would not quite have made contact medially because of

their narrowness. How they articulated with the premaxillae and vomers is not known.

The medial features of the posterior half of the maxilla are exposed in BPI 2529

(Fig. 6A) and 4680 (Fig. 5B). This part of the maxilla is composed of a thin dorsal and

lateral part, and a thicker ventral and medial component. Posteriorly, as the maxilla tapers

to a point, the thick medial and thin lateral parts become separated and the small gap

between them receives the central flange of the divided anteroventral arm of the jugal to

form an intimately interlocking articulation. A small posterodorsally open pit lies between

the lateral and medial parts of the maxilla of BPI 4680 and 2529 (Fig. 6A), whereas the

condition in BPI 4540 and BMNH R3592 is less clear. BPI 4540 seems to have a small pit,

perhaps equivalent to that in BPI 2529 and 4680 but, positioned a short distance in front of

this, is a much larger pit. This seems to be equivalent to a similarly placed pit in

BMNH R3592, and they probably represent the posterior opening of a neurovascular

canal. The absence of the larger pit in BPI 2529 and particularly 4680 could possibly be

explained by poorer preservation. This feature is also seen in other archosaurs (e.g. Gower

1999) and probably has a broad distribution.

The medial surfaces of BPI 4680 and 2529 bear scars that are interpreted as the area of

articulation with the palatine.

18 ANNALS OF THE SOUTH AFRICAN MUSEUM

S.popr

s.mas s.1 D

Figure 7

Erythrosuchus africanus, NM QS1473 skull roof. A. Ventral view. B. Lateral view of anterior part.

C. Ventral view of anterior part. D. Posterior view of anterior part, not to same scale.

The nasal (Figs 2, 3, 7, 8) is a long and narrow bone forming much of the anterior part

of the skull roof. Behind the naris, a large vertically descending flange bears a broad,

shallow groove that receives the posterior process of the premaxilla. Here the nasal is at its

ventral limit, and it separates the posterior process of the premaxilla from the ascending

process of the maxilla (Figs 2, 3). The posteroventral edge of the vertical nasal flange

articulates with the groove on the anterior edge of the ascending maxillary process. A

bevelled posteroventral edge and a shallow groove at the posterior limit of the vertical

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 19

nasal flange (Fig. 7B, C) articulate intimately with the rest of the tapering maxillary

process. A second groove, originating a short distance behind this, receives the dorsal

edge of the anterior arm of the lacrimal.

Sutural contact between the nasal and the overlapping frontal and prefrontal is

achieved via long interdigitating processes (Fig. 8). A transverse section through the skull

roof of NM QS1473 shows that the prefrontal is also intimately received by an

invagination on the dorsal surface of the nasal (Fig. 7D). The ventral surface sutures with

the prefrontal and frontal are less strongly interdigitating. The ventral surfaces of the

nasals carry the anterior part of a wide channel for the olfactory tract, and an area for the

nasal glands (Witmer 1997: 12).

The lacrimal (Figs 2, 3) is currently known only from BPI 5207 and 3893. Dorsally, the

posterior border of the lacrimal articulates with the ventrolateral surface of the prefrontal.

Anterior to this is a thickened dorsolateral ridge that articulates with the prefrontal and the

posterolateral edge of the nasal. The lacrimal curves slightly downwards from this point to

contact the ascending process of the maxilla. The posterior end of the maxilla rests in a

groove between the inset ventral and raised dorsal levels of the stepped lateral surface of

the lacrimal. This stepped area contributes to the antorbital fossa (Fig. 2).

The descending arm of the lacrimal meets, and laterally overlaps, the anterior end of

the jugal. It also meets the posterodorsal corner of the maxilla but the details of the

articulation are unclear, even in BPI 3893—which is sectioned in this region (Fig. 3).

Most of the posterior margin of the lacrimal is excluded from the orbit by the prefrontal. A

pit on the border between the left lacrimal and prefrontal of BPI 5207 (Fig. 2C) possibly

indicates the posterior opening of the nasolacrimal canal. Details of the medial surface of

the lacrimal are unknown.

Dorsally, the prefrontal (Figs 2, 3, 7, 8) is anteriorly pointed and forms part of the

interdigitating frontal/prefrontal-nasal suture. The blunt posterior end is angular in

BMNH R3592 (Fig. 8), but more rounded in BPI 5207 (Fig. 2D) and NM QS1473 (Brink

1955). The dorsal surface is shallowly concave and sculptured with a curious pattern of

shallow labyrinthine canals, most clearly seen in BMNH R3592 and GHG AK82-22.

These canals are present on most of the dorsal surface of the skull roof, but are notably

concentrated towards the lateral edge of the prefrontal. They bear a slight resemblance to

the less extensive canals present on the dorsolateral margin of the prefrontals of

Sphenosuchus acutus (Walker 1990).

The lateral edge of the dorsal part of the prefrontal is thickened, particularly

posteriorly, to form a prominent overhanging brow. Running longitudinally on the

posteroventral part of this ridge is a narrow groove, clearly seen in BMNH R3592

(Fig. 8B) and BPI 5207 (Fig. 2). Ventrally, this thickened area of bone ends in an abrupt

step marking the lateral limit of a pronounced depression on the ventral surface of the

skull roof in the area of nasal, frontal and prefrontal contact (Figs 7A, 8C).

The prefrontal pillar forms the anterior border of the orbit and articulates with the

lacrimal. Its ventromedial extent is currently unknown.

The frontals (Figs 2, 7, 8) exist as paired, unfused elements forming the major part of

the skull roof. They are broad posteriorly and narrow anteriorly, where long interdigitating

ANNALS OF THE SOUTH AFRICAN MUSEUM

Figure 8

Erythrosuchus africanus, skull roof of BMNH R3592. A. Dorsal view. B. Left lateral view.

C. Ventral view.

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 7/1

processes are sandwiched between the nasals, ventrally, and the prefrontals, dorsally. The

frontals form part of the short dorsal border of the orbit—at the point where contact is

made with the posterior part of the prefrontals. The opposite frontals meet at a well-

defined midline suture that is anteriorly simple, but posteriorly weakly interdigitating.

Weakly interdigitating sutures are also present at the point of frontal-parietal and

frontal-postfrontal contact. The only well-preserved frontal-parietal suture (NM QS1473,

Fig. 7A) is slightly curved. No contact is made between frontal and postorbital on the

dorsal surface of the skull roof. The dorsal surface of the anterior of the frontals is

essentially flat, but posteromedially they form the anterior limit of a steep-sided

subrectangular depression that extends back on to the parietals. This is the “pineal fossa’

described by Parrish (1992).

The centre of the ventral surface of the frontals bears a posterior continuation of the

channel for the olfactory tract (Figs 7A, 8C). The posterior limit of the midline frontal

suture lies in an additional channel that broadens out as it extends back on to the parietals.

Shallow depressions border the dorsal margins of the orbits on the ventral surface of the

frontals of BMNH R3592 (Fig. 8C), and possibly GHG AK82-—22 (absent in

NM QS1473). The posterolateral part of the ventral surface of each frontal bears a large

depression that is steep-sided and extends on to the postfrontals, postorbitals, and

parietals. Only the posterior limits of these depressions receive the capitate processes of

the laterosphenoids. Ventral contact between the frontal and postorbital excludes the

postfrontal from the posterodorsal border of the orbit.

The postfrontal (Figs 2, 7, 8) 1s a small element that is tightly bound between the

frontal, postorbital, and parietal. Dorsally it contributes to the posterodorsal border of the

orbit. Much of the lateral border of the prefrontal is enveloped by the postorbital, and

posteriorly brief contact is made with the parietal. The ventrolateral edge of the

postfrontal is thickened, and the thinner posteromedial edge contributes to the depression

that articulates with the capitate process of the laterosphenoid. In NM QS1473 only a

small area of the postfrontal is exposed ventrally (Fig. 7A), and here it no longer

contributes to the border of the orbit, although contact with the parietal is maintained.

The opposite parietals (Figs 2, 7-9) are firmly articulated but suturally distinct. They

are short, fairly broad, and have well-developed posteroventral transverse processes.

Laterally, and behind where contact is made with the frontals, postfrontals, and

postorbitals, the thickened edges of the parietals form the medial borders of the

supratemporal fenestrae. The central parts of the parietals are much thinner and bear the

posterior extension of the pineal fossa back from the dorsal surface of the frontals. There

is a fairly large and slightly irregular hole in the centre of this fossa in BMNH R3592

(Fig. 9D). Huene (1911) believed this to be a pineal foramen-a plesiomorphic feature for

archosauromorphs—but doubt has been cast on the naturalness of this hole by subsequent

workers (Charig & Reig 1970; Parrish 1992). Brink (1955) and Parrish (1992) reported

the absence of a pineal foramen in NM QS1473 and Parrish (1992) also reported its

absence in BPI 5207. Following an examination of all of these specimens, it is reported

here that the hole in BMNH R3592 has become slightly larger and more irregularly

shaped since it was last figured (Huene 1911, fig. 1). It is also positioned somewhat

ANNALS OF THE SOUTH AFRICAN MUSEUM

“SMOTA [CUDA pu [eSIOp ‘[eIId1I990 Ul 76SEY HNING ‘°C ‘Mar [erd10900

Ul O89F Id ‘D “AMOIA [e}dI990 Ul CHOH [dq “| “MAIA [eNAIN90 UI €/ PISO WN “V ‘JOOd [[Mys ou} Jo Wed JoL1a\sod ‘snuvoisfo snyonsosyjArq

6 OINSIy

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM is}

off-centre with respect to the midline suture. It was not possible to determine whether a

small pineal foramen might present in NM QS1473 because of some restoration in this

region of the specimen. The skull of BPI 5207 was compressed laterally during

preservation and this means that the possible presence of a small foramen can not be

discounted. BPI 3893 was incompletely prepared in this area at the time of this study, but

is also laterally crushed here. In short, conclusive evidence on the presence or absence of a

pineal foramen in Erythrosuchus africanus 1s not currently available.

The tall and broad occipital surface of each posteroventral transverse parietal process

is essentially smooth, although two notable features are a dorsomedially positioned

tubercle and, nearer the ventral edge, a subhorizontal transverse groove (Fig. 9). The

dorsolateral edge of the occipital surface of the process of NM QS1473 (Fig. 9A) bears

horizontal striations. The ventral surface of the process holds a well-defined and triangular-

shaped socket for articulation with the dorsomedial edge of the paroccipital process. This

articulation results in a post-temporal fenestra that was, at most, a narrow slit. The

ventromedial edges of the transverse processes present a smoothly convoluted surface

(BMNH R3592) for articulation with the supraoccipital.

The ventral surface of the roof of the parietals closely matches the dorsal contours of

the laterosphenoids. Anteriorly there are small triangular ventral processes that rest

between the capitate and anterior processes of the laterosphenoids. Longitudinal grooves

on the ventral surface of these parietal processes form the dorsal surface of an

‘anterodorsal channel’ (see Gower & Sennikov 1996b; Gower 1997). A well-defined

ventral concavity surrounds the central hole in the parietals of BMNH R3592. This area

has been partially restored in NM QS1473.

The small postparietal (Figs 2, 7—9) is firmly sutured to the parietals, and projects

posteriorly as a short, free-standing pyramidal peg—a feature possibly restricted to

erythrosuchids (see also Gower & Sennikov 19965). Its tapered anterior end is wedged

between the posterior end of the parietals, and contact is also made with the supraoccipital

ventrally.

The postorbital (Figs 2, 3, 7) is an unevenly triradiate bone. Its short anterior arm

articulates with the anterolateral and posterolateral margins of the postfrontal, as well as

the anterolateral edge of the parietal. The postorbital therefore excludes the postfrontal

from the supratemporal fenestra (Figs 2C, 7A). As pointed out by Charig & Reig (1970),

this arrangement is contrary to that reconstructed by Huene (1911). The postorbital makes

a small contribution to the ventral depression for the capitate process of the

laterosphenoid. The anteroventral portion of the anterior arm of the postorbital is laterally

thickened and this contributes to an overhanging ridge at the posterodorsal corner of the

orbit. A distinctive depression lies just behind and above this thickened area.

The posterior process of the postorbital is slightly arched and pointed seen in lateral

view, and it articulates with a deep notch in the squamosal. The lateral surface of the distal

end bears a narrow, slit-like groove (Fig. 2). This groove, clearly visible in both specimens

where this area is preserved (BPI 5207 and 3893, NM QS1473), is accentuated by laterally

raised borders. Parrish (1992) listed deep tongue-in-groove articulation between

postorbital and squamosal as an erythrosuchid synapomorphy. The incised groove

ANNALS OF THE SOUTH AFRICAN MUSEUM

‘Tesourenbs

WSL JO SMOIA [eIpow pur [eJoyey] “gq ‘[esourenbs jo] JO SMOIA [IPSUM pur [e1N}e] “VW ‘O89P Idd JO S[esowenbs ‘snupoiuifp SNYINSOAYJAAT

Ol canst y

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM Ze)

described here reflects a deep contact and might contribute to a clearer definition of a

more satisfactorily discrete character state.

The descending ramus of the squamosal (Figs 2, 10) is much longer than the anterior

one. Towards its ventral edge the posterior margin of this ramus bears a laterally

overhanging pleat or tuck (Fig. 10). This overhanging part forms a free-standing posterior

edge that sheaths laterally the dorsal part of the quadrate. The part of the squamosal that is

overhung continues ventrally to articulate with a depression on the lateral surface of the

quadratojugal. This squamosal pleat is perhaps restricted among the earliest archosaurs to

the erythrosuchids Erythrosuchus and Shansisuchus (personal observation of IVPP

material). The ventral process of the squamosal of E. africanus extends down towards the

posterior process of the jugal, and almost (BMNH R3592, BPI 4680) excludes the

quadratojugal from the border of the lateral temporal fenestra.

The medial surface of the squamosal is complex and articulates with the parietal,

paroccipital process of the opisthotic, the head of the quadrate, and the quadratojugal via a

series of concavities (Fig. 10).

The anterior process of the jugal (Figs 2, 3) is excluded from the border of the

antorbital fenestra. The dorsal edge of this same process forms the short ventral margin of

the orbit, which is smoothly notched by a small and rounded, jugal projection (Fig. 2B).

The anteroventral part of the anterior jugal process intimately interlocks with the maxilla.

The anterior extremity of the jugal consists of a medial overhanging projection and a thin

lateral flange, either side of a central ramus. The lateral flange is received by the gap

between the lateral and medial parts of the maxilla (described above), and the medial

projection articulates with the medial surface of the maxilla. This arrangement is also seen

in Proterosuchus fergusi (personal observation of RC 96), and possibly has a broad

distribution among early archosaurs.

The posterior process of the jugal is the longest, and forms the almost straight ventral

border of the lateral temporal fenestra, with the medial surface of the process contacting

the quadratojugal for most of its length. The anterior part of the articulation with the

quadratojugal is simple, with the medial face of the jugal contacting the lateral wall of the

quadratojugal. Posteriorly, however, the jugal tapers to a point and rests within a deep

notch on the quadratojugal. The quadratojugal (Figs 2, 11) is a complex element that

articulates with the jugal, squamosal and quadrate to form a robust posterolateral corner to

the dermatocranium. The bone consists of three main rami: laterally compressed anterior

and dorsal processes, and a more dorsoventrally compressed and anterodorsally inclined

posteromedial process.

The anterior process articulates with the ventromedial surface of the jugal, continuing a

long way forward as it does so, but never contributing to the ventral border of the lateral

temporal fenestra. The posterior part of the quadratojugal extends back from the dorsal

arm for a short distance, but it is largely expressed as a medial process that overlaps the

base of the quadrate posteriorly (Fig. 11A). This configuration of the quadratojugal

contributes to a large posterolateral and dorsal concavity in the lower posterolateral corner

of the skull, lateral to the lower half of the quadrate.

ANNALS OF THE SOUTH AFRICAN MUSEUM

0894 Idd JO syeApenb 19] JO MATA JOLIASO_ D 089h Idd JO Hespenb

JYSII JO MOIA JOLAISOg “G “76SEU HNN JO [esnloyespenb pue oye1penb iyo] JO SMOIA [elaje] pue IOLIN\SOg “W ‘snuvoiufo snyonsosysdugq

[] oIns1y

[b's

Bete

Res peed aaivenieinaees

ofb

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 27

Palatal complex

The palate is the poorest known part of the skull. Information is available from

incompletely prepared and/or disarticulated and fragmentary specimens only. The palatal

contributions of the premaxilla and maxilla are described above.

The vomer of Erythrosuchus africanus is currently unknown. It should be preserved,

but is currently not visible, in the specimens BPI 5207 and BPI 3893. The only clue to its

form may come from the close resemblance (personal observation) of the other known

palatal elements to those of Garjainia prima (Ochev 1975).

The palatine is currently known from a single incomplete example belonging to the left

side of BMNH R3592 (Fig. 12), and a glimpse afforded by the anteriormost transverse

section of BPI 3893 (Fig. 3C, D). The BMNH R3592 example is the bone described and

figured by Huene (1911) as a vomer. Ochev (1975) interpreted this bone as a palatine, and

it very closely resembles that element in Garjainia prima and Vjushkovia triplicostata

(Ochev 1975; personal observation). It is very different from the long, slender, and

strongly dorso-ventrally compressed palatines of, for example, Proterosuchus

(Cruickshank 1972) and Prolacerta broomi (Gow 1975). It is constructed of thin

lamellae—a lateral one articulates with the maxilla, and a medial one with the pterygoid.

These meet near the anterior end of the palatine but they diverge posteriorly—contact

being maintained between the two by a third, more horizontal lamella. The horizontal

lamella and part of the medial one form part of the roof of the mouth.

The lateral lamella is essentially flat on its outer face, although centrally it bears a

narrow triangular depression. Anteriorly, the incomplete lamella seems to be tapering to a

point and, just behind this, the medial lamella joins it. A thickened and subcylindrical

dorsal process is present at the point where these two lamellae meet. The notch between

the anterior edge of this process and the dorsal part of the anterior extension of the lateral

lamella, forms the posterior border of the choana. Both the dorsal process and the thin

medial lamella probably continued upwards and forwards, as in Garjainia prima and

Vjushkovia triplicostata (Ochev 1975), to contact the posterior end of the vomer as well as

the anterior of the pterygoid. A small area anterior to this is irregularly roughened and

bears two circular pits. It is unclear if these are simply irregular growths or likely to be

characteristic for the species. It seems unlikely that this pitted, roughened area was

associated with palatal teeth.

Palatal teeth are present in at least one erythrosuchid, based on a re-examination of the

palatines of V. triplicostata. One of these, PIN 951/18, was incorrectly described by

Ochev (1975) as a left-side element. Contrary to Ochev, the palatines of V. triplicostata

clearly exhibit a number of small, blunt, conical teeth as well as some empty pit-like

‘sockets’. This is the first report of the presence of palatal teeth in erythrosuchids. Palatal

teeth are known in proterosuchids (e.g. Cruickshank 1972; Gower & Sennikov 1997;

Welman 1998), but their absence was previously thought to have characterized the clade

consisting of all archosaurs other than proterosuchids (e.g. Benton & Clark 1988; Sereno

1991; Parrish 1992). Although the pits on the palatine of BMNH R3592 approximately

resemble the empty ‘sockets’ in V. triplicostata, a similarly rough and pitted surface is

seen on some non-palatal elements of the BMNH R3592 material (e.g. anterior fragment

28 ANNALS OF THE SOUTH AFRICAN MUSEUM

dep

30 mm

Figure 12

Erythrosuchus africanus, left palatine of BMNH R3592. A. Lateral and slightly dorsal view.

B. Ventrolateral view. C. Dorsomedial view. D. Medial and slightly ventral view.

A B C

30 mm

Figure 13

Erythrosuchus africanus, right ectopterygoid of BPI 4680. A. Medial view. B. Lateral view.

C. Ventral view.

of left jugal). Furthermore, the pits on the palatine of BMNH R3592 are few in number

and relatively rather large.

At the point where the central lamella meets the lateral lamella, two foramina pass

between the floor of the dorsal hollow and the ventral edge of the palatine. The palatine of

Garjainia prima also exhibits a foramen in this region (Ochev 1975, fig. 3). A low and

weakly defined ridge extends anteromedially along the floor of the dorsal hollow, from a

position just anterior to the complete foramen.

The palatine is also visible in the anteriormost section through BPI 3893. Details are

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM AY)

Figure 14

Erythrosuchus africanus, right pterygoid of BMNH R3592. A. Lateral view. B. Medial view.

C. Ventral view. D. Dorsal view.

hard to interpret, partly due to the angle of the section, but Figures 3C and D shows the

palatine contacting the ventrolateral edge of the pterygoid and articulating with the medial

maxillary wall. Evidence for this also comes from the medial ‘scars’ seen on some of the

maxillae (see above). This specimen, and comparison with G. prima (Ochev 1975),

indicates that the opposite palatines probably did not meet along the midline.

Most of the information on the morphology of the ectopterygoid comes from single

examples from BPI 4680 (Fig. 13) and BMNH R3592, both from the right side. The

articular surface for the jugal is subquadrangular with an anterior notch (Fig. 13B). It is

almost certain that the ectopterygoid did not contact the maxilla in addition to the jugal. A

substantial tapering process stems from the articular head and extends posteriorly,

medially, and ventrally. The medial margin is incomplete in both examples but would

have articulated with the lateral margin of the ventrolateral ramus of the pterygoid. The

dorsal surface of the proximal part of the tapering posterior process bears a distinct

depression—giving this part of the ectopterygoid a concavo-convex transverse section.

The anterior margin 1s incomplete in both examples so that there is no indication of the

form of the posterior border of the suborbital fenestra. The BMNH R3592 example is less

well-preserved, slightly distorted, and was not identified or described by Huene (1911).

The only other direct information on the morphology of the ectopterygoids comes from a

glimpse through the right lateral temporal fenestra of BPI 5207 (Fig. 2B), which shows the

30 ANNALS OF THE SOUTH AFRICAN MUSEUM

0.2m

Figure 15

Erythrosuchus africanus, restorations of the mandible. A. Lateral view. B. More speculative medial

view. The text should be consulted for information on the confidence that can be had in these

restorations.

posterior part of the head of the ectopterygoid articulating with the medial surface of the

jugal, and one of the transverse sections through the skull of BPI 3893 (Fig. 3E, F).

The form of the ectopterygoid, with an articular head and a long posterior process that

extends to the end of the ventrolateral ramus of the pterygoid, is essentially the same as in

Proterosuchus (Cruickshank 1972) and Garjainia prima (personal observation).

Re-examination of PIN material shows that Ochev (1975) misidentified the distal end of

the posterior process of the ectopterygoid of G. prima as a thickened ventrolateral

pterygoid edge.

The pterygoids (Figs 2, 3, 14) are deep and narrow elements. It is unclear how far

forward the dorsally arched palatal ramus extends but, in the light of many other close

similarities to the palate of G. prima (Ochev 1975), it 1s probable that contact was made

with the posterior of the vomer. The posterior edge of the ventrolateral process is

considerably thickened and almost cylindrical. Most of its lateral edge would have

contacted the ectopterygoid.

In lateral view the quadrate ramus appears as a large, smooth and triangular-shaped

surface, whereas medially it can be seen that it is trough-like in form, with a low medial

wall. The floor of this ‘trough’ articulates with the pterygoid process of the quadrate. The

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 3]

basal articulation is seen as a roughened and possibly incomplete oval surface on the end

of a horizontal ridge on the medial face of the central body of the pterygoid (Fig. 14B).

The sections through the skull of BPI 3893 (Fig. 3) show that an interpterygoid vacuity

was present along most of the length of the pterygoids. This becomes steadily narrower

anteriorly, and is eventually lost as the pterygoids appear to make contact along the

midline (Fig. 3D). There are no teeth on any part of the pterygoid. As Ochev (1975: 102)

realized, Huene (1911: 10, pls 1, 7) turned the right pterygoid of BMNH R3592 upside

down and referred to it as the left.

The quadrate of Erythrosuchus africanus is quite well known. It consists of a ventral

condylar area, a subvertical central ridge and an anteromedial lamella. The central ridge of

the quadrate (Fig. 11) is slightly bowed in lateral view. The base is expanded laterally to

provide a shallow depressed area for articulation with the medial arm of the quadratojugal.

The ventral surface of this area forms a kidney-shaped condyle. Just above the depression

for the quadratojugal, and about one-third up the height of the quadrate, is a postero-

laterally facing pit. This was described by Huene (1911) as the quadrate foramen but it is a

blind hollow, similar to a closed pit in the same position in Sphenosuchus acutus (Walker

1990). The quadrate of Stagonolepis robertsoni has a blind pit lying medial to an open

foramen (Walker 1961).

The quadrates of BMNH R3592 and BPI 4680 are incompletely preserved along their

lateral edges, but they present no evidence for the presence of a large quadrate foramen.

BPI 5207 shows minimal lateral compression here, and confirms that a quadrate foramen

was absent in Erythrosuchus africanus. Although absent in some species, e.g. Spheno-

suchus acutus (Walker, 1990), the quadrate foramen is a persistent feature present in

many fossil archosaurs, including proterosuchids (e.g. Cruickshank 1972; Gower &

Sennikov 1997), Garjainia prima (Ochev, 1981), Euparkeria capensis (Ewer, 1965),

aetosaurians (e.g. Walker 1961), and rauisuchians (Gower 1999).

Epipterygoids are not clearly visible in any specimen. A glimpse of the epipterygoid

through the right lateral temporal fenestra of BPI 5207 (Fig. 2B) shows that it was similar

in structure to those of other non-crown-group archosaurs (e.g. Garjainia prima—Ochev

1975; Proterosuchus—Cruickshank 1972; Clark et al. 1993), in having a broad base that

contacts the dorsal part of the pterygoid, and a slender dorsal process.

MANDIBLE

The lower jaw is fairly well known except for some details of the medial surface. It is

composed of seven elements and there is a well-developed lateral mandibular fenestra. A

reconstruction in lateral and medial view is shown in Figure 15. The reconstructed lateral

aspect is considered to be accurate, but medial details of the area of prearticular-

dentary-splenial-coronoid contact remain poorly known and are more speculatively

reconstructed.

The anterior of the dentary is dorsoventrally expanded (Fig. 2). As has been suggested

for crocodylomorphs exhibiting a similar condition (Parrish 1991; Sereno & Wild 1992),

the upturning of the anterodorsal margin of the dentary may be a developmentally more

ANNALS OF THE SOUTH AFRICAN MUSEUM

50 mm

sym

40 mm

Figure

Anterior part

in ventral view.

f the mandible of BPI 3893

10r part o

anus. A. Anter

hus afric

srythros

left

ht dentary

10r part oO

C. Anter

ht lateral view

f section through right ramus seen in A. E. Medial view of r

in rig

of the mandible of BPI 3893

sterlor View O

w. D. Po

al vie

iter

of BMNH R3592. F. Medial view of right dentary of BMNH R2790..G. Isolated tooth of BMNH R3592.

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 33

consistent feature than any accompanying dorsoventral expansion of the distal end. Among

non-crown-group archosaurs, however, this feature may be restricted to erythrosuchids.

Posteriorly, the dentary divides into three processes that taper to points (Fig. 2). The

uppermost process articulates with a notch on the lateral surface of the surangular. The

central process is marginally the largest and is directed slightly medially as well as

posteriorly—so that it is wedged between the lateral surface of the angular and the medial

surface of the surangular. The ventral edge of this process forms the anterodorsal border of

the lateral mandibular fenestra. The lower process articulates with the angular by

overlapping it laterally and resting on a small shelf. This configuration is present in

Garjainia prima (Ochev 1981; personal observation), and it might be common to a wide

range of basal archosaurs. It also appears to be similar to that described for Herrerasaurus

ischigualastensis (Sereno & Novas 1993). The only notable difference is the presence, in

H. ischigualastensis, of a lateral ridge on the dorsal process. The condition in

Erythrosuchus africanus 1s also. similar to that of at least some Recent crocodilians

(lordansky 1973; personal observation), where the central of three dentary processes

passes medial to the surangular. In crocodilians the dorsal process is much reduced and

the central process is more intimately sutured to the surangular. The condition in

H. ischigualastensis is therefore not unique (contra Sereno & Novas 1993: 469) apart

from, perhaps, the lateral ridge.

The anterolateral end of the Meckelian canal tapers to a point level with the position of

the fifth alveolus. The dorsomedial surface of the dentary bears an anteriorly tapering and

step-like depression that possibly held an elongate coronoid. BMNH R2790 shows a series

of parallel channels, presumably vascular, running back posteroventrally over this step.

The dentaries of BMNH R2790 and R3592 suggest that the splenial did not reach the

symphisis, but terminated at a point level with the fourth or fifth tooth alveolus. BPI 3893

(Fig. 16) demonstrates that the splenial formed much of the ventral as well as the medial

wall of the Meckelian canal, with the ventral contribution increasing posteriorly. Contact

with the coronoid is made posterodorsally, but anteriorly the dentary would appear to lie

between these two elements. Each dentary holds approximately 13 teeth.

Knowledge of the coronoid is far from complete. Direct evidence of its presence was

found only in BPI 3893 (Figs 3, 16), where the coronoid can be detected as a sliver of bone

on the dorsomedial edge of the mandible. This demonstrates that the coronoid was more

extensive than a crescent at the anterodorsal border of the adductor fossa, but clear

evidence for the limit of its anterior extension is lacking—it may even have extended far

anteriorly, lying between the dorsomedial edge of the dentary and the dorsolateral edge of

the splenial. In non-archosaurian archosauromorphs such as rhynchosaurs (e.g. Huene

1938) and Prolacerta broomi (Gow 1975), the coronoid does not extend far anteriorly

alongside the dentary, and in living archosaurs it is a small crescent of bone

(crocodilians—e.g. Iordansky 1973) or absent (birds—e.g. Baumel & Witmer 1993).

There is evidence that the coronoid was long and slender in some extinct archosaurs,

including the erythrosuchid Garjainia prima (Ochev 1981; personal observation), the

proterochampsid Chanaresuchus bonapartei (Romer 1971), and _ the early

crocodylomorph Sphenosuchus acutus (Walker 1990).

34 ANNALS OF THE SOUTH AFRICAN MUSEUM

Figure 17

Erythrosuchus africanus, surangular and articular of BMNH R3592. A. Lateral view of right ramus.

B. Medial view of right ramus. C. Dorsal view of right ramus. D. Ventral view of right ramus. E. Medial

view of left ramus. F. Lateral view of left ramus.

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 39)

The surangular (Figs 2, 3, 16, 17) is composed of a laterally-compressed posteroventral

plate that is suspended from an angled longitudinal ridge. The tapered anterior end of the

dorsal ridge bears a conspicuous notch (Fig. 17A, F) that receives the upper posterior

process of the dentary. The central dentary process passes under the ventral edge of the

anterior end of the surangular to contact the lateral face of a ventrally opening trough on

the ventromedial surface of the surangular ridge. This area of the surangular has collapsed

slightly during preservation in BPI 5207, so that it is expressed as a lateral depression

(Fig. 2B).

Posteriorly, the dorsal ridge forms the lateral edge of the mandibular cotyle. A thin

process extends anteromedially from the anterior margin of this area—its ventral edge

maintains contact with the upper surface of the plate-like part of the surangular, and its

posterior face firmly abuts against the anterior of the articular. Below the cotyle, the

thickened part of the dorsal ridge ends abruptly in a stumpy posterolateral projection.

Most of the lateral face of the ventral plate of the surangular bears a shallow depression

that receives the medial face of the posterior part of the angular. A large surangular

foramen is seen laterally, below the anterior edge of the cotyle and under the overhanging

dorsal ridge. A narrow and shallow groove extends anteriorly from this foramen,

harboured by the overhang of the dorsal surangular ridge. The groove becomes slightly

broader as it extends anterodorsally over the ventrolateral edge of the dorsal ridge, where

it eventually disappears.

The articular (Fig. 17) is a thick bone that forms the major portion of the mandibular

cotyle and retroarticular process. The cotyle is subdivided into two depressions by a slight,

diagonal ridge. The anteromedial surface of the articular articulates with the posterior part of

the lateral face of the prearticular. Behind this contact, the posteromedial surface of the

articular bears a prominently projecting tubercle. A narrow channel running below this

tubercle, and an associated foramen further up on the medial face of the retroarticular

process (Fig. 17B, D), may have served to transmit the chorda tympani branch of the facial

nerve. The low, rounded retroarticular process is formed by a small part of the surangular as

well as the articular. Among the earliest archosaurs, it resembles that of Shansisuchus

shansisuchus (personal observation of [VPP material documented by Young 1964) in that it

lacks the free-standing, dorsally projecting process at the end of the retroarticular region

present in Garjainia prima and proterosuchids (personal observation).

Current knowledge of the prearticular (Figs 2, 16) is also incomplete. The posterior end

is forked and articulates with the articular and the ventromedial edge of the ventral lamella

of the surangular. Most of the dorsal edge was free standing, and the ventral edge

articulated with the angular, and probably contributed to the infra-Meckelian fossa. Very

little is known of the anterior end of the prearticular, although a small piece of bone visible

in BPI 3893 (Fig. 16C) suggests that it extended far enough anteriorly to rest between the

posterior ends of the splenial and coronoid. Nothing is known of the lateral surface except

a glimpse afforded through the right lateral mandibular fenestra of BPI 5207 (Fig. 2B).

The angular (Figs 2, 3, 18) articulates with most of the other mandibular elements. A

small lateral shelf near the anterior end presents an area for articulation with the lower

posterior process of the dentary. Posteriorly, the lateral face is dorsoventrally expanded,

36 ANNALS OF THE SOUTH AFRICAN MUSEUM

Figure 18

Erythrosuchus africanus, left angular of BMNH R3592. A. Lateral view. B. Medial view.

and it overlaps laterally a large area of the posteroventral lamella of the surangular and a

small ventral part of the articular.

The central portion of the angular forms the floor of the large adductor fossa. A notch

in the dorsal margin of the medial part (Fig. 18B) probably represents the position of the

infra-Meckelian foramen—its margin being completed by the prearticular.

DENTITION

The marginal teeth of Erythrosuchus africanus (Fig. 16G) are typical of many

carnivorous archosaurs in that they are large, laterally compressed, recurved, sharply

pointed, and serrated. The mesial edge is more rounded than the sharply tapering distal

margin, and the labial edge is more convex than the lingual one. The serrations on the

distal edge extend from the pointed tip to the base of the crown, but mesially they extend

for only half of the length from tip to crown. The teeth have long cylindrical roots that are

embedded within sockets in the jaw. The bone at the edge of each alveolus of fully

developed teeth is in close contact with the fully developed tooth surface, without

approaching the condition seen in proterosuchids (see Gower & Sennikov 1997). Sections

through the teeth show layered dentine surrounding a central lumen. There appears to be

minimal variation in form throughout both the upper and lower jaw.

The premaxilla holds five teeth. The first three alveoli are fairly equal in size but the

last two are markedly smaller, and are situated in the broad notch between the premaxilla

and maxilla. The first maxillary tooth is similar in size to the last of the premaxilla. From

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM ay)

here, there is an increase in tooth size posteriorly, up to a point where the maxilla is at its

deepest and the largest maxillary tooth is held. The alveolar depth decreases steadily from

here to the posterior end of the maxilla, but the size of the erupted crowns of the teeth is not

noticeably reduced until the last few teeth, which are markedly smaller.

Knowledge of the mandibular dentition is far from complete. It is likely that the

mandibular dentition did not oppose the first and last few teeth of the upper jaw. Potential

variation in tooth size along the length of the dentary is unknown, because no specimen

reveals enough information. It is probable that a general decrease in size occurred

posteriorly, with the largest teeth being held by the deep anterior part of the dentary.

Tooth replacement in Erythrosuchus africanus occurred by the emergence of the new

tooth in a position lingual to the functional tooth, with the alternate tooth replacement

pattern seen in many ‘thecodontian’ archosaurs. The replacement teeth in the two sides of

the upper jaw are out of phase. Evidence comes from the premaxilla of BMNH R3592

(Fig. 4C), where the right side has functioning teeth in the first and third alveoli but a

replacing tooth in the second, and the left side has a replacing first tooth and a large

functional second. Further evidence comes from BPI 5207 (Fig. 2), where large

functioning third and fifth maxillary teeth border a smaller, replacing fourth tooth. The

right maxilla of the same specimen shows the opposite situation.

VERTEBRAL COLUMN

Vertebrae and ribs

Only a few of the known specimens of Erythrosuchus africanus include vertebrae, and

none exhibits a complete series. Furthermore, preservation and/or preparation is often

imperfect, making the identification of the exact position of isolated vertebrae

problematic. It has been possible, however, to discern most of the morphological

characteristics associated with changes in serial position. These closely follow those

known for other early archosaurs (Hughes 1963; Cruickshank 1972).

There are two sacral vertebrae and an estimated 25 presacral vertebrae, also the number

in Proterosuchus (Cruickshank 1972) and as estimated for Vjushkovia triplicostata by

Huene (1960). The almost complete tail of BMNH R3592 indicates that there were

approximately 35 caudal vertebrae. All of the presacral vertebrae are notably short

relative to their height, particularly in the pectoral region, and the centra are consistently

taller than they are long throughout the presacral column. The centra are platycoelus to

amphiplatyan and are laterally constricted or excavated. The dorsal neural arches are

pierced by often complex, subdivided pits or foramina. These are perhaps pneumatic in

nature (Gower 2001), but this requires further investigation because pneumatized

vertebrae are generally considered to be restricted to more derived archosaurs (e.g. Britt

1994; Britt et al. 1998). Intercentra are present throughout the length of the precaudal

column and three-headed ribs are present in the pectoral region.

It is probable that all of the precaudal vertebrae bore ribs. Unfortunately they are

incompletely known, largely because articulated postcranial specimens have not been

found. This is particularly true of the presacral ribs, where much of the information had to

38 ANNALS OF THE SOUTH AFRICAN MUSEUM

OLIol

+r, ~~ _—CeestsOir—/— eA

€ a e

Figure 19

Diagrammatic views of vertebra showing dimensions recorded in Tables | and 2. a = centrum length;

b=centrum height anteriorly; c = centrum width anteriorly; d = centrum height posteriorly; e = centrum

width posteriorly; f = length of base of neural spine; g = length of distal end of neural spine;

h = longitudinal distance between tips of zygapophyses; 1 = maximum transverse distance across

anterior zygapophyses.

be gained from the corresponding articulatory surfaces on the vertebrae. The sacral ribs

and most of the caudal ribs are well known. Measurements of a number of vertebral

dimensions, defined diagrammatically in Figure 19, are presented in Tables | and 2.

Identification of a proatlas is uncertain. Squashed on to the lateral surface of the right

atlas neural arch of BPI 4680 (Fig. 20A) is a slender splint of bone, similar in shape and

relative size to the proatlas of Euparkeria capensis described by Ewer (1965). The

presence of a proatlas in Erythrosuchus africanus is also suggested by an anterior

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM sy

20 mm

Figure 20

Erythrosuchus africanus. A. Medial and lateral views of right atlas neural arch of BPI 4680. B. Anterior

and posterior views of atlas intercentrum of BPI 4680. C. Medial and lateral views of right atlas neural

arch of BMNH R3592. D. Anterior and posterior views of atlas intercentrum of BMNH R3592.

projection on the atlas neural arch, articulatory facets on the exoccipitals, and by the

presence of a proatlas in other early archosaurs.

The neural arch of the atlas (Fig. 20A, C) consists of a main body with a small anterior

projection and a longer, tapering posterior process. The arches are paired and unfused,

with the gap between them being partly overhung by the axis neural spine. The element as

a whole is laterally convex and medially concave. The main part of the arch contacting the

atlas intercentrum is short, broad, and transversely thick. The anterior edge forms an area

for articulation with the occipital condyle. The anterior projection arises dorsally, just

behind the anterior margin of the main body. It continues for a short distance antero-

medially before contacting the proatlas. There are two hollows at the base of the anterior

projection—anteromedially and posteriorly.

The intercentrum of the atlas is well preserved in BPI 4680 and BMNH R3592 (Fig. 20B,

D) as a crescent-shaped wedge of bone very similar to that of Euparkeria capensis (Ewer

1965). Posteriorly the ventral edge is bevelled, and posterolaterally each side forms a single

facet for articulation with what was probably a single-headed rib. The atlas centrum and axis

intercentrum have not been identified or preserved in any currently known specimen.

The centrum of the axis (seen in BPI 5207, Fig. 21A) is short and unkeeled, and the

anterior surface is perhaps more convex than in the other vertebrae of the column. The

anterodorsal part of the lateral edge of the centrum 1s raised to form what is interpreted as a

weakly expressed diapophysis. This facet is in a significantly more dorsal position than

the diapophyses of the following cervical vertebrae, such as is also seen in Proterosuchus

40)

ANNALS OF THE SOUTH AFRICAN MUSEUM

par

BNE Nera petit eT

arte

par

Figure 21

Erythrosuchus africanus. A. Right lateral view of axis and incomplete third presacral vertebra of

BPI 5207. B. Right lateral and anterior views of third(?) presacral vertebra of BMNH R3592. C. Right

lateral view of anterior cervical vertebra of SAM-—3028. D. Right lateral and anterior views of cervical

vertebra of BPI 4680. E. Right lateral, ventral and anterior views of slightly more posterior cervical

vertebra of BPI 4680. All scale bars represent 20 mm.

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 4]

(Broili & Schroder 1934). There is no indication of a parapophysis below this. The neural

spine is incomplete but was clearly expanded. The atlas and axis ribs are unknown.

The anteriormost cervical vertebra might be represented by an incomplete example

from BMNH R3592 (Fig. 21B; Hughes 1963). The centrum is much taller than it is long

and bears circular parapophyseal and diapophyseal facets low down on its lateral surface.

Other anterior cervicals (SAM-—3028, BPI 4680—Fig. 21), have more circular faces to the

centra, and the ratio between height and length is less (Table 1).

A number of changes in morphology occur in moving posteriorly along the cervicals

and approaching the pectoral region (Table 1). The centra become taller, shorter

longitudinally, and show increased lateral constriction. The articulatory surfaces become

more circular in shape and the ventral margins remain bevelled. The parapophysis

remains low down on the anterior edge of the centrum, but the facet becomes

dorsoventrally elongated, whereas the diapophysis ‘migrates’ up the anterior edge.

BMNH R3592 includes two fairly well-preserved posterior cervical centra that,

because of their distinctive morphology and the aforementioned problem of deducing

their exact position, are referred to here as ‘pectoral vertebrae’. They are described in

some detail here because of the evidence they provide for the presence of three-headed

ribs. The more posterior centrum (Fig. 22B) was artificially stuck to a complete neural

arch and spine, and was considered by Charig & Reig (1970) to be a composite. Charig &

Reig used this as evidence in rejecting Tatarinov’s (1961) claim that facets for three-

headed ribs could be identified in this specimen. The centrum and arch have since been

separated. BMNH R3592 includes an additional disarticulated neural arch (Fig. 22C) and

centrum that are similar in form to the equivalent components of the former composite

example. The former composite arch fits this second, isolated centrum very closely, as

does the free arch with the former composite centrum, and the interpretation here is that

this was the original configuration. It is also suggested that these two vertebrae articulated

directly with one another in the column, with the formerly composite centrum and isolated

arch belonging to the more posterior (?ninth) of two consecutive vertebrae. In both

examples, the centrum forms only a small part of the diapophysis, whereas the

parapophysis remains low down on the anterolateral edge.

Although the two pectoral centra of BMNH R3592 share almost identical morphologies,

the corresponding neural arches show some differences. The ventral processes of the more

posterior arch (Fig. 22C) are much more prominent, more horizontally directed, and more

sculptured than in the preceding example. The distal end of the diapophysis does not form a

simple oval-shaped facet, but is instead constricted to present two quasi-discrete areas

(Fig. 22C). The larger upper area is oval-shaped and its long axis leans back at

approximately 45° to the vertical. The second area forms part of a smaller and more circular

facet with the diapophyseal component of the centrum. This arrangement strongly suggests

the presence of three-headed pectoral ribs very similar to those of Vjushkovia triplicostata

(Huene 1960; personal observation). This is supported by the presence of three heads in a rib

of Erythrosuchus africanus described below. BPI 4680 and SAM—PK-K10025 both

include a number of fragmentary, crushed and isolated centra, that are posterior cervicals

or possibly anteriormost dorsals. These are listed as pectorals in Table 1.

42 ANNALS OF THE SOUTH AFRICAN MUSEUM

TABLE 1

Various dimensions of precaudal vertebrae in five specimens of Erythrosuchus

africanus. The dimensions a—g are defined in Figure 19. AC = anterior cervical;

CE = cervical; P = pectoral; D = dorsal; AMD = anterior/mid dorsal; MD = mid dorsal;

MPD = mid/posterior dorsal; PD = posterior dorsal; S = sacral

; Estimated Dimensions (mm)

Specimen position : * : F : ‘

BMNH R3592 (large) , oo

AC 3 57 110 77

CE 50 109

CE 61 105 107 90

8 58 123 101 iD 105 32

9 54 125 106 123 113 34 32

AD 12 65 118 97 114 93 42

AMD 15 68 105 91 96 91 51 72

AMD 16 72 103 90 100 85 52 74

MPD 20 78 102 89 58 B

MPD D 78 94 85 98 82 56 16

S S1 72 97 85 100 75 42 45

S S2 69 100 75 90 70 35

BMNH R3592 (small) _

MD 16 85 65

MD 17 62 82 59 16 59 39

MD 18 61 86 62 719 64 42

MD 19 56 83 64 78 64 42

MD 20 Ti 64

PD 24 62 79 68 79 65 45 |

ee er

AC 3/4 48 16 66 81 69

INC 4/5 59 82 64 86 70

PC 7 41 87 80 84 80

8 44 87 75 91 80

9 Al 92 W) 93 78

10 91 86

AD 1 Al 85 81 81 75 29

AD 13 89 84 80 70 35

AMD 14 77 75 74 70 37

MD 74 67 65 62

MD 19 59 80 65 78 60

DO 78 69 67 68

DO 69 68 66 62

DO 35 66 68

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 43

Specimen Estimated Dimensions (mm)

position q b c d 2 ¢ g

SAM K3028

AC 4/5 SD) 79 65

SAM K905

MD 62 90 73 95 85

PD 7A 90 73 16

PD 69 95 73

SAM Kun-no.

AC 47 81 65

CE 49 79 58 80 65

CE 48 15 65 Z

I 74 ug

P 42 82 80 73

AD 40 88 75

AD 85

AD 48 80 q7.

DO 68

DO 70

DO 47 67 65

DO 51 13

DO 52 66 56

DO SD US

Anterior dorsal vertebrae are represented by single but relatively well-preserved

examples from BMNH R3592 and BPI 4680 (Fig. 23). The centrum is longer than those of

the ‘pectoral’ vertebrae and the articulatory faces are not so circular. The neural arch is

still distinct suturally from the centrum, but is more complex in form. The simple and

single diapophyseal facet is situated on the end of a near-horizontal transverse process that

is subtriangular in cross-section. A lamella extends between the di- and parapophyses, and

additional lamellae extend from the base of the transverse process. One of these is the

development of the anterior ridge extending on to the lateral surface of the anterior

zygapophysis, whereas another extends posteroventrally to the posterior edge of the

centrum. Finally, a moderately developed posterior ridge extends to a position just below

the posterior zygapophysis. There are two deep pits where the bases of the anterior and

ventral lamellae converge. A similar pit is also positioned between the anterior and

posterior zygapophyses—at the dorsal edge of the base of the transverse process.

Moving posteriorly along the dorsal series there is a general increase in centrum length

and a decrease in height (Table 1). All of the dorsal centra (Fig. 24) show strong lateral

constrictions. The neural arch pits become more complex, with each main excavation

housing a number of smaller ones separated by narrow lamellae (Fig. 24B). The anterior

pit becomes large and occupies much of the concave anterior surface of the transverse

process. Further posteriorly in the column, as the parapophysis migrates dorsally, the

anterior pit again becomes shallow and simple. The ventral pit gradually becomes less

ANNALS OF THE SOUTH AFRICAN MUSEUM

QIT YO] JOF SJoow} JO oUITINO snyd ‘MorA JOLOyUe UI Yore [eINSU IOLIA\Sod aIOy ‘D ‘WIN.WUdD JoOTIO}sod o10N JO SMOIA [BUDA pur [e1a}e] OT -g

York [PANU IOLOJUL SIOU JO MIIA [BSIOP pu IOLI9\sod ‘[esojey WYSTY WV ‘T6SEU HNN JO seIQoUI9A [eIOJood SATINIOSUOD OMY ‘SnUDIL{D snyonsosyJAAT

CT? ANSI

208 "p

THU QE Jed

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM

‘O89 Idd JO BIQOLIOA [LSIOP JOLIOJUL JO MOIA JOLIOISOd “CG “TOSEU HNIN JO PIQOHOA [eSIOp JOLIOJUB JO MIA TeSIO “D “coSed HNN

JO VIQOIIOA [LSIOP IOLIOJUL JO MITA [L19}R] YOT

‘J °Z6SEM HNING JO BAQOLIOA [BSIOP JOLIOVUL JO MOIA IOLIOWWY “YW “snUuDILIfY snyonso4LypAs]

€7 ONS

ANNALS OF THE SOUTH AFRICAN MUSEUM

“UWI ()€ JUSSOIdaI SIeg BBO “[ENPIAIPUL JO[[eWIs JO 9v1Qd}19A |[eSIOP JOLIO\sod ysour

IU} JO UO JO MATA [LIDIL] YO] “| “LAQSLIIA [PSIOP IOLI9}SOd JO MOIA JOLIOSOg “C] “VIQSWSA [BSIOP JOLI9}SOd JO MOIA IOLIOWUY “dD ‘PIGOLIOA [esIOp

JOIIN}SOd JO MOIA [BIOL] JOT “G “PIQOVIOA [SIOP-PIU JO MOTA [RIDE] YOT “VW “76SEU HNING JO 2eIGoVI9A JesIop ‘snuvotifo snyansosypArq

y¢ cnsIy

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 47

well defined as the posteroventral lamella recedes. The dorsal pit becomes steadily bigger

and deeper, and is often complex. The arch also becomes pierced by foramina along the

posterior edge of the base of the transverse process and behind the posteroventral lamella.

These posterior foramina become less obvious as the posteroventral lamella recedes. The

facets of the anterior and posterior zygapophyses become more horizontally inclined. The

neural spines are long narrow blades with narrow ‘spine tables’.

In an isolated, possibly last, dorsal vertebra (Fig. 24E) from the smaller-sized material

belonging to BMNH R3592, the anterior neural arch pits are absent, but the dorsal and

posterior ones are highly reduced—only the ventral pits remain well defined. Additional

pits are positioned near the proximal end of the facets of the posterior zygapophyses.

These neural arch pits are similar to those that can be seen in a wide range of archosaurs,

including, for example, rauisuchians (personal observation). They are possibly pneumatic

(see Gower 2001), although pneumatized vertebrae are considered at present to be

restricted to ornithodiran archosaurs (Britt 1994). Erythrosuchus africanus certainly lacks

the large pneumatic foramina in the centra of some ornithodiran archosaurs (e.g. Britt et

al. 1998).

An almost complete and articulated example of the sacral vertebrae and ribs is

preserved as part of BMNH R3592 (Fig. 25). Erythrosuchus africanus has two sacral

vertebrae, the first of which is distinctly larger than the second. The first sacral centrum is

circular in end view and is taller than it is long. The anterior edge is ventrally bevelled,

probably for articulation with an intercentrum. An intercentrum is preserved in position

between the two sacral vertebrae of BMNH R3592. The second sacral vertebra is similar

to the first, with a few notable differences. It is smaller and the centrum has an oval-shaped

posterior articulatory surface. The facet for the second sacral rib occupies a more posterior

position. The possibly pneumatic pits characteristic of the neural arches of the preceding

dorsals are absent or greatly reduced on the sacral vertebrae, except perhaps for an

excavation behind the process that bears the facet for the first sacral rib.

The caudal vertebrae are well represented by a largely complete and articulated series

belonging to BMNH R3592, described only briefly by Huene (1911). There are some

glued breakages that may not all be true, but the first 31 caudal vertebrae are well

represented. There are at least a further three (and an estimated maximum of five)

associated vertebrae. This, together with the fact that at least one vertebra is missing from

the tip of the tail, means that the total number of caudal vertebrae was approximately 35.

Other specimens include only unassociated examples or fragments, so that possible

variations in form and number cannot be assessed currently.

There are a number of changes in morphology along the tail, with the dimensions of

some of these variables in BMNH R3592 shown in Table 2. The first caudal vertebra

(Fig. 26) is short and high, much like the second sacral vertebra. The single articulatory

area for the fused caudal rib is large. The second caudal vertebra (Fig. 26D) is smaller

than, but similar to the first. Bevelling of the ventral part of the centrum suggests the

presence of an intercentrum in life. Huene (1911) considered the first two caudal vertebrae

to be ‘caudo-sacral’—believing that the ribs would have contacted the medial surface of

the ilium. Although the available evidence (abrupt tapering of the preserved part of the

48 ANNALS OF THE SOUTH AFRICAN MUSEUM

ribs, absence of articulatory areas on the ilium) does not support this view, it is true that

the first two caudal vertebrae are laterally flanked by the posterior part of the iliac blade.

WANS ILS, 2

Variation in dimensions of caudal vertebrae in Erythrosuchus africanus, specimen

BMNH R3592. The dimensions a—i are defined in Figure 19.

Position Dimensions (mm)

a b c d e h 1

l 63 87 71 86 70 76 50

2 62 78 67 76 80

3 68 64

4 58 72 71

5 » 68 66 67

6 54 67 67 64

7 53 66 63 61 V7 50

8 54 61 60 58 1S 48

5) 53 57) 53) yy) WS 43

10 yy 53 49 49 72 45

1] Sl 50 47 46 72 43

12 49 48 43 43 70 36

13 48 45 42 42 69 35

14 48 38 39) 69 34

15 48 38 38 69

16 47 38 35 36 65 30

17 46 35 34 65 29

18 44 35 34 35 61 28

19 44 34 331 58 Di

20 43 30 33 31 26

21 42 32 30 34 32 53 26

22 40 33 30 31 30 53 DS

23 39 Sil 2) 28 28 47 23

24 39 30 28 28 26 Dy)

DS 29 26

26 38 DY 26 50

Dy 37 26 26 49 19

28 35 24 24 46 Ig

29 34 23 26 7B

W303 21

3] 20 19

32 30 18 19 18

33 19 17

34? De 14 16 13 35)

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 49

Figure 25

Erythrosuchus africanus, sacral vertebrae and ribs of BMNH R3592. A. Anterior view.

B. Posterior view.

Several changes occur over the following eight or so caudal vertebrae (Fig. 27A,

Table 2). There is a proportional lengthening of the centra up to a point where the centrum

of the tenth caudal vertebra is longer than it is high. This is accompanied by a decrease in

the absolute length and diameter of the centra. There is also a reduction in the expression

of lateral constriction. The ventral edge remains arched, but the keel is reduced, and the

ventral surface becomes a broad and almost flat area. The bevelling on the posteroventral

edge of the centra becomes kidney-shaped for articulation with haemal arches. The

contact areas for ribs decrease in size, and are positioned lower down on the vertebrae.

The articulatory surfaces of the zygapophyses become longer and narrower, and are at a

greater angle to one another (the anterior zygapophysial facets of the ninth caudal vertebra

are separated by an angle of 125°). The base of the neural spine becomes shorter and 1s

positioned further posteriorly. This change occurs fairly abruptly at the eighth and ninth

caudal vertebrae. The complete neural spine of the eleventh caudal vertebra is fairly short

and laterally compressed, but has a moderately expanded distal surface. It projects

posterodorsally at an angle of approximately 45° to the long axis of the centrum.

The relative lengthening of the centra and reduction in the size of the rib contact areas

continues along the remainder of the tail (Fig. 27, Table 2). By the twenty-fourth caudal

vertebra the neural spine is but a low, thin crest. Posterior to the twenty-fourth caudal and

up to the end of the tail, the angle between opposite zygapophyseal surfaces again

narrows—to a point where they are almost vertical, and significant lateral movement of

the tail would have been greatly restricted. In a horizontal plane the tail would have been

stiff at its base and again towards the tip, with more potential for movement between these

points. By the twenty-ninth caudal vertebra there is no longer a contact area for a caudal

rib, and by the thirty-second the neural spine is reduced to a barely perceptible ridge.

ANNALS OF THE SOUTH AFRICAN MUSEUM

“BIQOWOA

[EPNES PITY} FO MOIA [BIO IL] YO] “| “VIQOLIOA [PEPNLd puodas JO MATA [e19}L] 19] ‘(| “VIQOVIOA [EPNed JSIIJ JO MOIA IOLIDISOg “dD “BIQOVIOA [epned

ISI JO MOIA [B1D}L] YO] “ “CIGSLIOA [BPNLO ISI JO MOTA JOLIOWUY “VW ‘Z6SEU HNING JO esqov9A [epneos Joloyue ‘snupoifo snyonsoaysaag

QZ oIns1 4

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM oul

The presacral ribs are poorly known. BMNH R3592 includes one fairly complete

cervical rib (Fig. 28A) and some additional fragments. The shaft of the cervical rib is

short, laterally compressed but slightly concavo-convex, and tapers to a point. The

capitulum and tuberculum are short, and their facets lie close together. The tubercular

facet is circular but the capitular one is more oval in shape. A small leaf-shaped and

laterally compressed anterior process of the shaft projects forward between the capitulum

and tuberculum. Grooves, possibly for blood vessels, are located on the ventro- and

dorsomedial edges, just behind the base of the tuberculum and capitulum. The other

known fragments of cervical ribs show no notable deviation from this morphology.

The pectoral ribs of early archosaurs are of particular interest because of a number of

claims and refutations of the presence of three-headed ribs (Huene 1960; Tatarinov 1961;

Hughes 1963; Ewer 1965; Charig & Reig 1970; Cruickshank 1972; Thulborn 1979; Peng

1991; Parrish 1992). Excepting Tatarinov (1961), it has generally been accepted that

three-headed ribs were not present in Erythrosuchus africanus. Most recently, Parrish

(1992) has claimed that three-headed ribs are present only in the pectoral region of

Vjushkovia triplicostata Huene, 1960, and V. sinensis Young, 1973, and that they are a

synapomorphy of the genus Vjushkovia. Evidence from a pectoral vertebra belonging to

BMNH R3592 described above, suggests however that they were present in

Erythrosuchus africanus. An incomplete rib belonging to SAM—3028 (Fig. 28B) offers

further support for this interpretation. It is an almost complete proximal end with a short

fragment of shaft. There is no anterior process, the capitular and tubercular ‘peduncles’

are confluent with the proximal end of the shaft, and the articulatory facets are oriented

virtually perpendicular to the long axis of the shaft. The ventral margin is arched but the

dorsal one is nearly straight.

The capitular facet is oval-shaped and simple. The tubercular facet is slightly larger

and more circular, and closely associated with its ventral edge is a small but discrete

accessory facet. The posterior view of this rib shows that this third facet is not just an

expanded area of a lamella between the capitular and tubercular facets, but that it is

associated with its own cylindrical peduncle. This arrangement is very similar to the

pectoral ribs of Vjushkovia triplicostata (Huene 1960; personal observation). This rib

morphology, combined with the above description of the pectoral vertebra of

BMNH R3592 with three apophyses, provides the first detailed osteological evidence that

three-headed ribs were present in Erythrosuchus africanus. The presence of three-headed

pectoral ribs is not therefore a unique synapomorphy of the genus Vjushkovia (see also

Gower & Sennikov 2000).

The evidence from the apophyses of the anterior dorsal vertebrae is that the anterior

dorsal ribs were dichocephalous. Substantial shaft fragments and a possible distal end of a

large dorsal rib belong to BMNH R3592, but no proximal ends are known. Posterior

dorsal ribs (e.g. Fig. 28C) are known only from proximal fragments.

The sacral ribs (Fig. 25) are short, stout, and ventrolaterally directed. They are very

firmly attached to the sacral vertebrae, but a suture is still evident. The ribs of the first

sacral vertebra are much larger than those of the second. Anteromedially they protrude

beyond the anterior surface of the centrum to provide additional articulatory surfaces for

ANNALS OF THE SOUTH AFRICAN MUSEUM

‘OBIQOLIOA [epnes YyNoJ-Ayry} puwe pary}-AUTY LH “ovIQOWOA Tepes pIy}-ALIUY 0} ISIJ-AYNY_L, “J “dVIQOLIOA [epnes

\sJ-AVITY] pure YJOHATYL, “Y “OeAQOVIOA [epneo yyUTU-AJUIM4 OF YYLY-AJUOM | “(| “OvIQOVIOA [epned YyVINOJ-AWUOA\} 0} JSIEJ-AJUIM |, *D “9PIQOLIOA Jepneo

POU) 0} YJUSAIY “| “OkIQOLIOA [EpNLd YUDAIJO 0} YLINO “VW “Z6SEU HNIN JO svAGoLIOA [epNed JO SMOIA [eIO}L] Yo] ‘snUDILfd snyonsosyaag

LZ 9INBI

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 53

the centrum of the last dorsal vertebra. The second sacral ribs articulate with the more

posterior part of the vertebra, and do not extend beyond the posterior edge of the centrum.

All of the caudal ribs (Figs 26, 27) are holocephalous and are firmly attached to the

vertebrae, although a suture can often be detected. The ribs of the first two caudal

vertebrae have very robust heads, but the short shaft tapers distally. The remaining ribs are

all dorsoventrally flattened, short, and project downwards and slightly posteriorly. They

become shorter and more slender along the length of the tail, before disappearing by about

the twenty-ninth caudal vertebra.

Intercentra and haemal arches

The presence or absence of intercentra has been employed as a character that has

importance for the resolution of early archosaur relationships (e.g. Benton & Clark 1988;

Sereno 1991; Parrish 1992). Despite some debate over the presence of intercentra in

erythrosuchids (e.g. Charig & Reig 1970) it is clear that intercentra were present

throughout the precaudal column in Erythrosuchus africanus. This 1s partly demonstrated

by the obvious bevelling on the anterior and posterior ventral edges of the centra. Contrary

to Parrish (1992), intercentra are preserved in some specimens of E. africanus. One is

preserved in BPI 4680 (Fig. 28F), and three articulated dorsal vertebrae from

SAM-—PK-K 10025 show intercentra preserved in articulation (Fig. 28E). An intercentrum

is also present between the two sacral vertebrae of BMNH R3592. The first two caudal

vertebrae of BMNH R3592 show bevelling, yet not the expanded kidney-shaped area of

the more posterior caudals. This suggests that intercentra but not haemal arches were

present here. The anterior edge of the third caudal centrum is not preserved, but between

the third and fourth and all subsequent caudals there are haemal arches, but no sign of

separate intercentra. This is different from the condition in Proterosuchus, where separate

caudal haemal arches and intercentra are present (Cruickshank 1972).

Haemal arches (Fig. 28D), or chevrons, are present from between at least the third and

fourth caudal vertebrae up to the end of the tail. They all share the same general structure

in possessing a broad, hour-glass or kidney-shaped proximal end, and a posteroventral

Y-shaped distal process. They articulate largely with the broad area on the posteroventral

bevelled edge of each caudal centrum, although contact with the anteroventral edge of the

following centrum is also achieved. The anteriormost haemal arches have long and almost

cylindrical distal ends, but several changes in form occur along the tail. They become

shorter more abruptly than the decrease in length of the corresponding centra, and the

openings for the passage of the blood vessels of the tail become smaller. The distal ends

gradually become laterally compressed, and they also develop a projecting, lamella-like

anterior edge. The lateral compression is combined with a small degree of torsion, so that

the right side of each haemal arch is rotated anteriorly and the left side posteriorly. There

is direct evidence of haemal arches being present at the thirty-second caudal vertebra, and

further indirect evidence (in the broad bevelling of centra) that they were present beyond

this and possibly up to the tip of the tail.

54 ANNALS OF THE SOUTH AFRICAN MUSEUM

cap

Figure 28

Erythrosuchus africanus. A. Lateral and medial views of anterior right cervical rib of BMNH R3592.

B. Medial and anterolateral views of left pectoral rib of SAM—3028. C. Medial and anterolateral views

of left posterodorsal rib of BMNH R3592. D. Anterior views of the anteriormost and a slightly more

posterior haemal arch of BMNH R3592. E. Ventral view of dorsal centra and intercentra of

SAM—PK—K 10025. F. Anterior and lateral outlines of isolated intercentrum of BPI 4680. All scale bars

represent 15 mm.

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM bie)

APPENDICULAR ELEMENTS

Limb orientation terminology

The clarity of osteological descriptions and their usefulness in comparative studies is

often clouded by the lack of a definition of the terms used to orient limb surfaces. In

choosing a set of clearly-defined and practical terms, it is here intended to use those based on

form rather than on a postulated and potentially incorrect life position. This avoids the

vagaries of discrete gaits, that are usually too rigid and generalized (e.g. Jenkins 1971). The

terminology used here is based on the early (‘primitive’) tetrapod condition, rather than that

used in dinosaurian, avian, and mammalian studies—groups generally considered to have

an ‘upright’ gait. This terminology therefore aims to agree with that already established in

the osteological and myological description of extant quadrupedal archosaurs (for example,

that applied to crocodilians by Romer 1942), despite the additional problems caused by

differences in the relative position of homologous surfaces on single elements among

different taxa. Romer (1922, 1923, 1942) defined the dorsal and ventral surfaces for the

propodial elements of the fore- and hindlimb of early tetrapods. The ventral surface of the

‘primitive’ tetrapod humerus, as described by Romer, is broadly equivalent to the anterior

surface of the dinosaurian (or mammalian) humerus, but the ventral surface of the

‘primitive’ tetrapod femur is equivalent to the posterior of the dinosaurian femur. This

difference is a result of the flexural differences between the fore- (at the elbow and wrist)

and hind- (knee and ankle) limb. This disagreement represents a fundamental problem in

attempting to employ a consistent terminology for limb orientation.

In the works cited above, Romer was not concerned with the epipodials or the

carpal/tarsal elements. Rewcastle (1980) approached this problem, with respect to the

hindlimb of extant lizards, by standardizing a terminology to a fully, anteriorly extended

limb. Rewcastle’s study concerned the hindlimb only, and did not have to confront the

problems concerned with translating this same reasoning to the forelimb.

Although the differences in flexure mean that some disagreement must remain

between the fore- and hindlimb terminology, the main objective is to be explicit about the

terminology used. With respect to the hindlimb, I follow Rewcastle’s (1980; see also

Gower 1996) terminology, but with the forelimb I attempt to apply some of Rewcastle’s

reasoning as well as following Romer’s traditional definition of dorsal and ventral. Thus

the long axes of all the limb bones are parallel to the long axis of the body in lateral view.

The ‘standard’ posture of the forelimb is with the radius, ulna, carpus, and manus fully

anteriorly extended, but the humerus fully posteriorly extended. The dorsal and ventral

surfaces of the epipodials and manus/pes can, of course, be termed extensor and flexor

surfaces respectively. Although explicit in its definition, it is realized that this

terminology is far from perfect, and that a ‘standard’ posture is ‘somewhat arbitrary’

anyway (Rewcastle 1980).

Pectoral girdle and limb

The only elements of the pectoral girdle of Erythrosuchus africanus that are currently

known are the scapula and coracoid. The slightly incomplete scapula of the type

ANNALS OF THE SOUTH AFRICAN MUSEUM

‘COSEU HNING JO ploseto9

JO] JO SMOIA [eIPSU pue [e19eT “g{ BZ7OLEU HNING JO B[ndeos 1YS11 JO SMOIA [VIPSW puK [eIOWeT] “VY ‘a[pPIIS [e10}O0d ‘snuvoiufp snyansosyjAsgq

6¢ SINS

OS's

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM D7,

specimen, SAM—905, was briefly described by Broom (1906). Only worn fragments are

preserved as part of BMNH R3592 (not described by Huene 1911), and there are two

incomplete and crushed examples preserved as part of SAM-—3028. The best specimen is a

well-preserved and complete right-side example—BMNH R3762a (Fig. 29A)—that is

shorter and more slender than that of the holotype.

The scapula (Fig. 29A) is tall, fairly slender, and much larger than the coracoid. The

long axis of the element is bowed so that the lateral surface is convex and the medial

surface concave. The anterior margin, when viewed laterally, is concave, whereas the

posterodorsal margin is neither strongly posteriorly directed nor tapering. The overall

outline of the scapula therefore resembles that of later archosaurs, and is the converse of

that seen in archosauromorphs more distant from the crown, such as Proterosuchus

(Cruickshank 1972) and Prolacerta broomi (Gow 1975).

The anterior margin of the scapula blade is thin, apart from a prominent anterolateral

process at the distal end. This might be termed the acromion process although there is no

direct evidence that its function was the support of a clavicle. Close to where the scapula

narrows to a ‘waist’, the posterior edge of the medial surface bears a thin, vertical ridge—

possibly associated with the origin of the m. subcoracoscapularis. A low ridge positioned

slightly distal to this, and close to the anterior margin, borders a shallow depression that

opens out on to the dramatically expanded distal end of the scapula.

The coracoid (Fig. 29B) is a remarkably small element compared with the scapula. The

anterior of the coracoid is thin and plate-like, but the posterior edges, particularly dorsally,

are greatly thickened—up to 4.5 times as thick as the anterior edge in BMNH R3592.

These edges are also highly rugose. The dorsally expanded area represents the ventral

surface of the glenoid fossa, which is quite different from that of Proterosuchus

(Cruickshank 1972) in being an essentially simple and posteriorly open notch—although

the socket in life may have been shaped largely by cartilage. The foramen for the passage

of the supracoracoid nerve is entirely within the coracoid.

The humerus (Fig. 30) is a short robust bone. The strongly expanded proximal and

distal ends are joined by a short, cylindrical shaft. The angle between the long axes of the

two end surfaces is approximately 30° in SAM—905S.

The ventral surface of the proximal end is dominated by a large deltopectoral crest. In the

largest specimens (SAM—905, BMNH R3592), the crest is almost rectangular in lateral

view and extends to almost halfway down the shaft. In smaller specimens (BMNH R3762,

SAM-—PK-K 10025), the crest is a less angular and less prominent feature, and the shaft is

more slender. In BMNH R3592, a rugosity on the lateral surface of the base of the

deltopectoral crest is interpreted as part of the area of insertion of the deltoid musculature.

The slightly concave and rugose surface of the distal end suggests that the capitellum

and trochlea were largely cartilaginous features in life. The supinator process is well

developed and its ventrolateral edge continues up on to the base of the deltopectoral crest

as a low supinator ridge. The dorsal edge of the supinator process forms the ventral border

of a deep ectepicondylar groove for the radial nerve and blood vessels.

The radius (Fig. 31A) of Erythrosuchus africanus is known only from a single,

complete example from the right side of SAM—905. The area of the proximal surface is

ANNALS OF THE SOUTH AFRICAN MUSEUM

‘Q]BOS OURS 0} 10U *76SEM HNWA

JO SHIOUINY JYSII JO SOUT[INO ISIOASUBI} JO SMOIA [BUNTXOLY “| SOG-IN'VS JO SNISUINY JYSLI JO MATA [eINIVT “G “SO6-INYVS JO Stuswny 13

JO MOTA [BNUIA “D “SO6-INVS JO SHIOUINY JYSIIJO MOIA [VIPS “G “SO6-INVS JO SHAOUINY JYSII JO MIA [esIog “y ‘snuvaLdf{d snyonsosyjAl

O¢ UNS

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM

"SMOIA [PB

WIxOId 91v SOUTINO OSIOASUB], “SMOTA [BUDA pur "]eIpoUl ‘Ies1op “Od

‘SMOIA [BIJUDA PUL “[RIPSU ‘dsJOASURI} ‘TeSIOP “[esoye] UL snipe WS “V “SO6-NVS JO

[¢ oNsIy

SIOASUBI} ‘[RIO}L] Ul BUTN WYSrY “_

sjeipodida quitjo1oy ‘snupoiifp SNYINSOAYJAAT

ANNALS OF THE SOUTH AFRICAN MUSEUM

7T6SEU HNN JO [edieovjour ypanoy yYys11

JO MOIA [eSIOC] “cD ‘s[edivovJOU 19] INOJ JSALJ JO MOIA [SIO] “| “SMITA OM} Ul Z6SEU HNINA JO [edeo o]qissog “y ‘snupotdfy snyonsodysAdgy]

TE ANSI

spine

pirat te

Pro Say

woo

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 61

much smaller, and the distal end larger, than the corresponding ends of the ulna. The

dorsal surface bears two clear ridges, possibly representing areas of muscle attachment.

The ulna (Fig. 31B) is slightly longer and more heavily built than the radius. As with

the radius, the only complete example is from the right forelimb of SAM—905. The

proximal articular surface is terminal and there is no ossified olecranon process above it.

The surface is rugose, concave, and sub-triangular in shape. The shaft is essentially oval in

cross-section and apart from a low medial ridge, and a less prominent lateral ridge, it is

relatively featureless. The lateral surface of the distal end is roughened and slightly raised.

The carpus and manus of Erythrosuchus africanus, as in many early archosaurs, is very

poorly known. A small spherical bone not belonging to the tarsus is among the material

belonging to BMNH R3592 (Fig. 32A). Its surface is poorly ossified apart from a saddle-

shaped area of roughened compacta. It is here tentatively identified as a carpal element.

As with the carpus, the only information on the rest of the manus of Erythrosuchus

africanus comes from BMNH R3592. There are elements of what are probably two

individuals of clearly different sizes. These probably correspond to the two individuals

represented by the two different size categories of vertebral material catalogued under the

same number. Belonging to the larger size category, and probably belonging to the

individual represented by the vast majority of specimen BMNH R3592, are the first four

left metacarpals (third and fourth incomplete) and the fourth right metacarpal (Fig. 32B, C).

Belonging to the smaller individual are the first three left metacarpals (third incomplete),

the proximal end of the second left metacarpal, and a single phalanx, probably from the

first digit. At least the left carpal material of the larger individual was originally

catalogued as part of DMSW R525. All of the metacarpals show torsion along their length

and the proximal ends are closely overlapping. Of the four metacarpals known, the first is

the shortest followed by the second, with the third being marginally shorter than the

fourth. Nothing is known of either the fifth metacarpal or of the phalangeal formula. The

larger metacarpals, particularly the proximal surfaces, are similar in size to the metatarsals

of the same specimen.

Pelvic girdle and limb

The pelvic girdle (Fig. 33) resembles that of other early archosaurs in having a short

pubis and ischium, and a closed acetabulum. All of the articular surfaces between the

girdle elements are rugose. The anterior extension of the crest of the ilium (Fig. 33A) is

not strongly developed (and becomes less obvious in larger specimens), but here it is at its

thickest, bears heavy dorsal striations, and was probably the area of m. iliofemoralis and

m. iliotibialis attachment. Ventrally, the medial edge of the crest is thickened, and the

dorsal edge remains narrow. The downturned sacral ribs and prominent supra-acetabular

crest combine to present a ventrolaterally directed acetabular socket.

The medial surface of the ilium bears the large, shallow, and sculptured depression that

receives the head of the first sacral rib. The depression for the second sacral rib is smaller

and extends for a short distance on to the anteroventral part of the base of the iliac crest.

The two depressions, separated by a low, vertical ridge, closely match the lateral surfaces

of the two sacral ribs.

ANNALS OF THE SOUTH AFRICAN MUSEUM

“siqnd JO SMOIA [eIpou

pue ‘[esioposoque ‘e198 “_ “UNIT JO SMOTA [eIPSU pur [eloeT “VW “76SEC HNN JO s}uowoye o[psis otajod yYys1I ‘snupatafo snyonsosysAuq

d ® VEE oinsIy

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 63

The pubis (Fig. 33B) forms the rather weak anteroventral border of the acetabulum.

The surface for articulation with the ilitum is greatly expanded to form a broad, triangular

area. This is much larger than the corresponding surface on the ilium and the excess forms

a rugose anteroventral acetabular border. The head of the pubis remains roughened and

raised in front of the anterior margin of the acetabulum, and this probably represents the

site of the m. ambiens origin.

The remainder of the pubis is composed of two confluent and flattened plates of bone.

One projects medially, in a horizontal plane from the head of the pubis, and the other is

oriented almost at a right angle to the first to form the short, downturned part of the pubis.

An oval-shaped obturator foramen is positioned close to the posterior edge and just medial

to the head of the pubis. The downturned plate has a greatly thickened and cylindrical

lateral edge that ends abruptly in a roughened surface.

The anterodorsal part of the ischium (Fig. 33C) is expanded to form the posteroventral

border of the acetabulum. The remainder of the element consists of a broad,

dorsomedially-ventrolaterally flattened, and slightly ventrally concave plate. A number of

ridges towards the posteromedial margin of the dorsal surface of the ischium might have

been associated with the origin of the m. ischiotrochantericus. The reconstructed angle

between the dorsal surfaces of the ischia when articulated is estimated to be

approximately 115° anteriorly and 45° posteriorly.

The femur (Fig. 34) of Erythrosuchus africanus is considerably longer than the

humerus—in BMNH R35972 the ossified part of the femur is approximately 1.25 times as

long as the estimated ossified part of the humerus. The proximal and distal articular ends

are terminal and their faces are approximately perpendicular to the long axis of the shaft.

Both end surfaces are rugose, concave, and bear a central longitudinal groove—

suggesting that substantial cartilaginous caps would have formed the finished articulatory

surfaces. The proximal and distal ends are slightly up- (dorsally) and down- (ventrally)

turned respectively, although to a lesser degree than is seen in, for example, Prolacerta

broomi (Gow 1975) and proterosuchids (personal observation). The shaft is robust and

shows some degree of torsion, with the long axis of the distal articulatory surface offset at an

angle of approximately 25° to the long axis of the proximal surface. The femur is not as

straight as in Proterosuchus (Cruickshank 1972; personal observation) when viewed

dorsally or ventrally, with the proximal end clearly deviating from the long axis of the shaft.

On the ventral surface of the proximal end there is a large and well-defined

intertrochanteric (adductor) fossa. Bordering this medially, and lying a short distance

away from the proximal terminus of the femur, is a prominent flange-like trochanter. This

was probably an insertion site for at least part of the caudifemoral musculature, based on

comparisons with extant lizards (Snyder 1954; Walker 1977) and crocodilians (Romer

1923; Walker 1977). The proximolateral surface of the trochanter, together with the fossa,

are interpreted as a probable insertion site of the m. puboischiofemoralis externus.

Extending diagonally from the distal end of the trochanter towards the lateral edge of the

distal end is a well-defined ridge (adductor crest) for the m. adductor femoralis.

The edge of the femur lateral to the intertrochanteric fossa is narrow proximally. It

broadens out abruptly at a point level with the distal termination of the intertrochanteric

ANNALS OF THE SOUTH AFRICAN MUSEUM

“UINIYOSI JO SMOIA [VIPAWIOSIOP puR [e1O}e]ONUDA ‘<C °

T6SEN HNWA JO S}uoWs[9 o[pIIs OTAlod JYSII ‘snuvoIAf{o SnYINSOAYJAAT

OEE ONS

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM

“MOTA [BIO}V'T] °C “MOIA [e.QUO A,

y's

“MOTIA [LUUTXOId UI SOUTTINO dSIOASUBIL “|

“J “MOIA [RIPSA “‘G “MOIA [RSIOG “VW "T6SEU HNINE JO ANwU9y YS ‘snudIIA{D SNYINSOAY]

pe ons

dod

raya)

wu 0g

ANNALS OF THE SOUTH AFRICAN MUSEUM

40 mm

feats

Figure 35A,B&C

C. Proximal part of right side in lateral view.

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 67

fossa, and forms an oval-shaped, dorsolateral swelling that extends distally to a point just

beyond one-third down the length of the shaft. This was identified as the trochanter major

by Gregory & Camp (1918, fig. 11), but Parrish (1992, fig. 2) considered it to be a fourth

trochanter. When the various trochanters are considered in terms of probable muscle

attachment sites, the identification of this as a fourth trochanter seems extremely doubtful.

The fourth trochanter of more derived archosaurs is a ventral feature positioned a

significant distance from the proximal end and, like at least part of the internal trochanter

of non-archosaurian diapsids, is a site for the insertion of caudifemoral musculature.

Whatever the name applied to this prominence, it seems a much more satisfactory

interpretation that this area, in Erythrosuchus africanus, was for the attachment of the

m. iliofemoralis and not the m. caudifemoralis, particularly when one considers the

actions that these muscles perform.

The ventral surface of the distal end of the femur is dominated by a large popliteal

space that, together with a wide. groove on the ventrolateral edge, extends about one-

quarter of the way up the femoral shaft. The dorsal surface of the femur is less contoured

(Fig. 34A). The dorsal part of the trochanter for the m. iliofemoralis can be seen on the

proximoposterior edge, and just proximal to this is a further scar that perhaps is the

insertion site of the m. ischiotrochantericus. Distally, there is a shallow and broad

intercondylar groove for the extensor tendon of the m. quadriceps femoris.

No complete tibia (Fig. 35) is known, but knowledge has been gathered from various

incomplete specimens representing proximal (BMNH R3592, left and right) and distal

(BMNH R3592, left and BPI 2096, right) ends. Huene (1911) interpreted the proximal

sections of the right tibia and fibula of BMNH R3592 (Fig. 35A—C) as distal ends. The

tibia is considerably shorter than the femur—an estimated 72 per cent of the length of the

femur in BMNH R3592. Approximately one-third down the length of the tibia the shaft is

cylindrical and at its narrowest. At this point and on the medial edge, there is a deep and well-

defined pit that is interpreted as a likely area for the insertion of the m. puboischiotibialis.

The shaft remains cylindrical and straight for the middle third of the tibia. At this

midpoint, at least, the shaft of the tibia is like that of the other limb bones for which clean

broken sections are available, in that it has a hollow core surrounded by a thin region of

cancellous bone. The gradual distal expansion of the tibia curves laterally towards the

fibula. A roughened area of bone and an adjacent low ridge on the dorsolateral surface of

the distal end might be the attachment site of a muscle lying between the hindlimb

epipodials. There is a similar, but more diffuse scar on the medial edge of the tibia. The

distal end of the tibia is almost circular in shape, and the surface is concave and weakly

ossified (Cruickshank 1978). Examination of the lateral surface of the distal end of the

tibia of BMNH R3592 supports Cruickshank’s (1978) suggestion that the ‘lateral process’

present in BPI 2096 is an artefact of preservation.

As with the tibia, there is no complete fibula (Fig. 35) currently known for

Erythrosuchus africanus. However, examination of various incomplete examples allows

a description of the whole element to be presented. These are BMNH R3592 (right

proximal), BMNH R3592 (formerly DMSW R525, left distal), and BPI 2096 (right

distal). In all cases these fibulae are clearly associated with the corresponding tibiae.

ANNALS OF THE SOUTH AFRICAN MUSEUM

‘f) 0} F soruedurosor seq 9]eds JaMoy ‘q 0} W sorueduIOsoR

qeq a[eos Joddy “ejnqy yo] Jo wed [eysIp Jo sMoIA yeuxosd pue JesIog ‘DH ‘e[nqy yo] Jo wed jeistp Jo smarA [e1sIp pue yenusA “4

“MOIA [BSIOP UI BIQH 19] JO Wed [esi] “| “MATA [erpour UI vIqQH yo] Jo ed [eUNIXOIg ‘ “Z6SEUY HNWA JO sso ‘snuparufo snyonsolyjasg

D # 4 “da ‘ase ounsiy

30 mm

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 69

The fibula is much more slender than the tibia, and the long axes of the proximal and

distal ends are approximately perpendicular to one another. The proximal limit of a

roughened and prominent scar for the m. iliofibularis is positioned about one-third of the

distance along the dorsolateral edge. This scar extends distally to a point just below

half-way down the shaft—by which point it has shifted to a dorsal position. A low but

well-defined ridge, distal to the m. iliofibularis scar and on the medial edge of the fibula, is

here interpreted as the possible fibular point of attachment of a muscle situated between

the fibula and tibia, possibly the m. interosseous cruris. An additional muscle scar forms

an unroughened, step-like ridge on the ventral surface of the fibula. The distal end surface

is oval in shape, gently concave, and covered in only a very thin veneer of compact bone

(as was possibly the proximal end before preservation/preparation). It is a little larger in

area than the proximal end.

The tarsus and pes have been described, at least in part, by Huene (1915, 1920),

Hughes (1963), Cruickshank (1978), and Brinkman (1981). Parrish (1992: 100)

questioned the referral of the tarsal material to Erythrosuchus, but Gower (1996)

supported the original identifications and presented a detailed redescription of the known

material.

GASTRALIA

The gastralia are poorly known but some examples are represented in three small

blocks of matrix belonging to BMNH R3592. These gastralia were not described by

Huene (1911), but are here interpreted as belonging to Erythrosuchus africanus. The best

of these examples consists of fragments of some 12 exposed, and additional unprepared,

abdominal ribs. The fragments are gently curved and slightly flattened hollow rods with

oval cross-sections. The cross-sections measure between 5 and 10 mm by between 4 and

6 mm and show an outer layer of solid bone surrounding a central area of more cancellous

bone. Nothing is currently known of the arrangement or extent of the gastralia.

OSTEODERMS

Osteoderms (= dermal armour/ossifications, scutes) are not generally thought to have

been present in the earliest archosaurs, but are instead currently considered to be a

synapomorphy of the more derived group Euparkeria+Proterochampsidae+crown-group

archosaurs (e.g. Benton & Clark 1988; Sereno 1991). Three specimens of Erythrosuchus

africanus suggest, however, that osteoderms have a wider distribution among archosaurs.

In his description of the holotype SAM-—905, Broom (1906) briefly mentioned an

element that he believed to be an unpitted dermal ossification (see also footnote in Charig

& Reig 1970: 133). A re-examination of this material has unfortunately failed to identify

which element Broom was referring to. Juul (1994: 6) reported the presence of rounded

osteoderms in BPI 5207, but that ‘the arrangement of these is uncertain’. The presence of

osteoderms in BPI 5207 was not noted during examination of that specimen in the course

of this study. The third specimen is BMNH R3592, which includes two possible

70 ANNALS OF THE SOUTH AFRICAN MUSEUM

15 mm

Figure 36

Erythrosuchus africanus, isolated osteoderm of BMNH R3592 in presumably outer and inner views.

osteoderms, neither of which was mentioned by Huene (1911). The first example, shown

in Figure 36 and not closely associated with any other element, is undoubtedly an

osteoderm. It is nearly circular and strongly flattened, with a pitted and well-ossified,

presumably outer surface, and a less completely finished inner surface. A small transverse

break reveals a cancellous interior with three internal canals extending parallel to the long

axis of the element (presumably also the long axis in life position). The second

BMNH R3592 example is closely associated with the caudal vertebrae (Fig. 27B). It is not

resting above a neural spine, but is instead preserved attached to the left lateral surface of

the sixteenth caudal vertebra. It is oval-shaped and has a strongly concave, presumably

outer surface, and a less concave inner surface. This more poorly preserved example

shows no indication of pitting on the outer surface, but it 1s also interpreted here as an

osteoderm. There is no evidence of any non-Erythrosuchus archosaur material being

collected with BMNH R3592.

Despite these possible examples of osteoderms, stronger evidence for their presence in

Erythrosuchus africanus 1s clearly required. The two described examples were not found

in life position nor do they exhibit a consistent morphology, not that one should

necessarily be expected. Very few specimens of E. africanus preserving articulated

postcranial material have been collected. The absence of intercentra (that were certainly

present in life) in the more complete postcranial specimens suggests that the lack of

osteoderms should not necessarily be taken as evidence of absence. An extensive set of

osteoderms are preserved in close association with the recently discovered erythrosuchid

skeleton (Pickford 1995) from the Omingonde Formation of Namibia (M. Kotzé, personal

communication 1999).

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 71

IMPLICATIONS

SKELETAL RECONSTRUCTION

A diagrammatic reconstruction of the skeleton of Erythrosuchus africanus is presented

in Figure 37. This is based largely on the specimens SAM-—905, BPI 5207, and

BMNH R3592. It represents the approximate proportions of the whole animal, and should

not be taken as a statement on locomotion or gait in the absence of a detailed functional

study. The skeletal reconstruction by Huene (1911) looks ungainly with an excessively

large skull, but the proportions he presented are approximately correct according to this

revision. Based on BMNH R3592, the estimated total body length is just over 4 metres.

Some incomplete specimens suggest a maximum size greater than this. Preserved among

the BMNH R3592 material is a fragment of a dorsal neural arch that measures 140 mm

between the tips of the anterior and posterior zygapophyses, and with a neural spine some

85 mm long at its base—an estimated total body length of 4.75—5 m, based on

extrapolation of proportions of the individual represented by the bulk of BMNH R3592.

}

SN eee

fk ny it <2 Re,

sldathsBOP™ a ata VES

Figure 37

Erythrosuchus africanus, restoration of whole skeleton in left lateral view. Excepting the carpals, all

unknown elements (several vertebrae, interclavicle, clavicles, and manual phalanges) have been

completely restored. This figure is intended to show the relative proportions of a skeleton approximately

the size of BMNH R3592 (total length 4 m+), and should not be taken as a statement on limb mechanics

or gait.

CRANIAL AND MANDIBULAR KINESIS

Although some of the cranial (including the braincase—Gower 1997) and mandibular

elements have features that suggest that they formed movable joints with other elements

in life, the available evidence is interpreted as showing that the skull and mandible were

not kinetic to any notable extent. For example, the dorsal surfaces of the laterosphenoids

are rounded (Gower 1997) and these articulate with depressions on the ventral surface of

the skull roof that are larger than the laterosphenoids, but these joints could not have been

72 ANNALS OF THE SOUTH AFRICAN MUSEUM

movable in the adult skull because the interdigitating frontal-parietal suture indicates that

it was a stiff structure in this region, and the braincase is otherwise in close contact with

the parietal. Similarly, the rounded head of the quadrate could not have rotated within the

squamosal depression in which it lies because the squamosal-quadratojugal and

quadratojugal-quadrate junctions seem to have been fairly firm. The premaxilla was not

firmly sutured to any element, but movement of this element in isolation was probably

limited, at most, to some sliding along the long axis of the premaxillary peg that articulates

with the pit on the anterior margin of the maxilla. The mandibular symphysis was not an

osteologically specialized region and some relative movement between the jaw rami may

have been possible, but the interlocking of the three dentary posterior processes with the

posterior elements of the mandible would have clearly limited movement from occurring

within each individual ramus.

The presence of potentially movable articulations between elements in an essentially

akinetic skull and mandible has also been noted in the rauisuchian Batrachotomus

kupferzellensis (Gower, 1999). This pattern of joint may have been important in allowing

minor, passive movement within the functioning adult skull (e.g. in transmitting forces

encountered during feeding), may have been a remnant from a more kinetic juvenile skull,

or is perhaps largely misleading in terms of movement in life.

TAXONOMY

Despite the relative wealth of erythrosuchid material that has been collected from the

Cynognathus Assemblage Zone of South Africa, it has never been suggested that the

material represents more than one species. This is in marked contrast to the South African

proterosuchid archosaur material from the Lystrosaurus Assemblage Zone, which has

been the subject of much taxonomic debate (see Charig & Reig 1970; Cruickshank 1972;

Welman & Flemming 1993; Welman 1998). The difference probably lies in the fact that

debates about the proterosuchid material has centred on a series of variably sized,

essentially complete, and fully articulated skulls—only two of which are known for

Erythrosuchus. The detailed re-examination of the South African erythrosuchid material

that formed the basis of the redescription of Erythrosuchus presented here, has also

allowed an assessment of the possibility that the material represents more than one

species.

A number of small variations in morphology have already been noted in the above

description. Some of these can probably be explained as ontogenetic or individual

variation, such as the shape and relative size of the deltopectoral crest, the slenderness of

the scapula, and the anterior projection of the dorsal iliac crest. The lower ratio between

the height and length, and the more circular articular surfaces of the cervical centra in

specimens (BPI 4680, SAM-—3028) from individuals that are smaller than BMNH R3592

is another possible example of growth-related changes in morphology. Other, possibly

non-growth related variations present more of a problem in that they are seen in

incomplete specimens that preclude detailed comparisons. For example, slight differences

exist among the skull roofs of BMNH R3592, BPI 5207, NM QS1473, and

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 73

GHG AK82-—22 and among the maxillae of BMNH R3592, BPI 4680, 2529, 4540, and

SAM-K1098, but two of the skull roofs and three of the maxillae represent all that is

known of these particular specimens.

The main variations that can not be clearly correlated with growth are noted here:

postfrontal excluded from orbit on ventral surface by frontal-postorbital contact (clearly

seen in NM QS1473, but probably absent in BMNH R3592); depression on underside of

skull roof surrounding dorsal orbit border (present in BMNH R3592; absent in

NM QS1473); posteromedial edge of dorsal surface of postfrontals (angular in

BMNH R3592 and BPI 5207; more curved in NM QS1473); dorsal frontal-parietal suture

(straight in BPI 5207; curved in NM QS1473); shape of antorbital fenestra (generally

oval, but possibly more circular in BPI 3893); maxillary projection notching the border of

the antorbital fenestra (only seen in BMNH R3592 and possibly SAM—K 1098); maxillary

dorsomedial pit(s) (see description above); position of internal carotid foramina on

basisphenoid (close to the midline in BMNH R3592; further apart in UMCZ T700—

Gower 1997).

All of these differences are slight, and covariance can not yet be studied. I support

Parrish (1992) in his recommendation that it is most prudent to currently retain all of this

material in a single species. As more complete material is collected and prepared,

allowing extensive comparisons between specimens, this may need to be revised. More

specimens might eventually make a quantitative assessment of the material worthwhile. A

future move to distinguish multiple species would probably present problems in that the

holotype (SAM-—905) of Erythrosuchus africanus consists of postcranial material only.

Cranial remains are currently assigned to E. africanus on the basis of their similarity to

specimens such as BMNH R3592 that consist of skull material plus postcranial remains

that resemble those of SAM-—905.

Tatarinov (1961) referred the Russian species Vjushkovia triplicostata and Garjainia

prima to Erythrosuchus, an assignment rejected by some subsequent taxonomic

assessments of early archosaurs (e.g. Charig & Reig 1970; Charig & Sues 1976; Sennikov

1995) and here. Another species of Erythrosuchus from Russia has since been described

by Ochev (1980) as E. magnus. Sennikov (1995) subsequently transferred this species to

the new genus Uralosaurus. The material consists of a pterygoid, an incomplete dentary,

and a few isolated teeth and incomplete vertebrae (see Gower & Sennikov 2000). Ochev

partly based his referral of this material to Erythrosuchus on similarities to the Russian

Vjushkovia triplicostata and Garjainia prima—accepting Tatarinov’s synonymy of these

genera with the South African Erythrosuchus (rejected here). A re-examination of the

material in question shows it to be similar to those elements of known erythrosuchids with

some slight differences (e.g. more curved dentary with low tooth count). The vertebral

centra are as tall or taller than they are long and clearly bevelled ventral edges, probably

for articulation with intercentra, can be seen on at least the anterior cervical example. This

material possibly represents an erythrosuchid distinct from those already known from

Russia and South Africa, but it is very incomplete, poorly known, and the association of

the separate specimens is uncertain.

Based on current knowledge of early archosaur osteology, there is no convincing

74 ANNALS OF THE SOUTH AFRICAN MUSEUM

intrinsic evidence for the presence of more than one species of Erythrosuchus. To date,

specimens of Erythrosuchus have not been found outside South Africa. The discovery in

Namibia of a partial skeleton with skull and mandible of a ‘proterosuchian cf.

Erythrosuchus africanus’ (Pickford 1995: 60) represents the first possible exception to

this. This is perhaps the most complete skeleton of an erythrosuchid yet collected, and it

will probably prove to be very important whether or not it represents EF. africanus. Study

of this material is now underway (M. Kotzé and R. M. H. Smith, personal communication

S12),

PHYLOGENY

In recent times (at least since Charig & Reig 1970), Erythrosuchus has consistently

been recognized as a member of the Erythrosuchidae—a clade including other Lower to

Middle Triassic archosaur taxa such as Shansisuchus from China and Garjainia prima

from Russia. Cladistic analyses have also reached a consensus that the Erythrosuchidae lie

outside the archosaurian crown group (Gower & Wilkinson 1996; Bennett 1996), but

there have been very few explicit phylogenetic considerations of the internal relationships

among erythrosuchids. Parrish (1992) conducted the first study and hypothesized that,

within the Erythrosuchidae, Erythrosuchus is more closely related than is Garjainia

prima to a clade composed of Shansisuchus+Vjushkovia (V. triplicostata+V. sinensis).

Gower & Sennikov (19966, 1997) did not consider V. sinensis or G. prima, but they

presented evidence supporting an alternative hypothesis in which Shansisuchus is more

closely related to E. africanus than it 1s to V. triplicostata. Gower & Sennikov (2000) have

since presented evidence that V. triplicostata should be considered a junior synonym of

G. prima.

A major proportion of Gower & Sennikov’s (19966, 1997) phylogenetic data came

from the braincase. This current study includes further support for the hypothesis that

Shansisuchus and Erythrosuchus africanus share a more recent common anestor with

each other than either taxon does with Garjainia prima (= Vjushkovia triplicostata). For

example, the Chinese and South African taxa share a premaxillary ‘peg’ that articulates

with a maxillary ‘socket’, a pleat/tuck on the posterior surface of the ventral process of the

squamosal, a short and low retroarticular process, and a quadratojugal that is nearly

excluded from the border of the lower temporal fenestra (Young 1964; Cheng 1980;

personal observation)—derived features absent in G. prima (personal observation).

Understanding of erythrosuchid interrelationships remains at a preliminary stage, and

several taxa have yet to be considered in explicit phylogenetic analyses: for example,

Guchengosuchus shiguaiensis Peng, 1991 and Chalishevia cothurnata Ochev, 1980. The

affinity of Vjushkovia (= Youngosuchus Sennikov in Kalandadze & Sennikov, 1985)

sinensis is currently in doubt, and Sennikov (in Kalandadze & Sennikov 1985) has

suggested that it is a rauisuchian rather than an erythrosuchid.

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM Ts

ACKNOWLEDGEMENTS

I would like to thank those people who provided useful information, encouragement,

discussion and advice, including Mike Benton, Arthur Cruickshank, Peter Forey, Chris

Gow, Barry Hughes, Dave Norman, Andrei Sennikov, Dave Unwin, Alick Walker, Larry

Witmer and an anonymous reviewer. I am grateful to Jo-Anne Friedlander for labelling

the figures and for final editorial touches. Staff at a number of institutions are thanked for

providing hospitality as well as invaluable assistance with material: in particular Sandra

Chapman and Cyril Walker (BMNH); Bruce Rubidge and colleagues (BPI); Johann

Welman (NM); Clive Booth, Anusuya Chinsamy, Sheena Kaal, Gillian King, and Roger

Smith (SAM); and Jenny Clack and Ray Symonds (UMCZ). Parts of this work were

funded by a NERC Ph.D. studentship (supervised by Mike Benton) and NERC grant

G9/1569.

REFERENCES

ANDERSON, J. M., & CRUICKSHANK, A. R. I. 1978. The biostratigraphy of the Permian and

Triassic. Part 5. A review of the classification and distribution of Permo-Triassic tetrapods.

Palaeontologia africana 21: 15-44.

BAUMEL, J.J. & WITMER, L. M. 1993. Osteologia. Jn: BAUMEL, J. J., KING, A. S., BREAZILE, J. E.,

EVANS, H. E. & VANDEN BERGE, J. C. eds. Handbook of Avian Anatomy: Nomina Anatomica

Avium: 45—132. Cambridge: Nuttall Ornithological Society.

BENNETT, S. C. 1996. The phylogenetic position of the Pterosauria within the Archosauromorpha.

Zoological Journal of the Linnean Society 118: 261-308.

BENTON, M. J. 1985. Classification and phylogeny of the diapsid reptiles. Zoological Journal of the

Linnean Society 84: 97-164.

BENTON, M. J. 1999. Scleromochlus taylori and the origin of dinosaurs and pterosaurs. Philosophical

Transactions of the Royal Society of London (B) 354: 1423-1446.

BENTON, M. J. & CLARK, J. M. 1988. Archosaur phylogeny and the relationships of the Crocodylia.

In: BENTON, M. J. ed. The Phylogeny and Classification of the Tetrapods: 295-338. Oxford:

Clarendon Press.

BRINK, A. S. 1955. Notes on some thecodonts. Navorsinge van die Nasionale Museum Bloemfontein

1: 141-148.

BRINKMAN, D. 1981. The origin of the crocodiloid tarsi and the interrelationships of thecodontian

archosaurs. Breviora 464: 1—23.

BRITT, B. B. 1994. Pneumatic postcranial bones in dinosaurs and other archosaurs. Journal of

Vertebrate Paleontology 14 (3, suppl.): 18A.

BRITT, B. B., MAKOVICKY, P. J., GAUTHIER, J. & BONDE, N. 1998. Postcranial pneumatization

in Archaeopteryx. Nature 395: 374-376.

BROILI, F. & SCHRODER, J. 1934. Beobachtungen an Wirbeltieren der Karrooformation. V. Uber

Chasmatosaurus vanhoepeni Haughton. Sitzungsberichte der Bayerischen Akademie der

Wissenschaften 1934: 225-264.

BROOM, R. 1905. Notice of some new fossil reptiles from the Karroo beds of South Africa. Records of

the Albany Museum 1: 331-337.

76 ANNALS OF THE SOUTH AFRICAN MUSEUM

BROOM, R. 1906. On the remains of Erythrosuchus africanus, Broom. Annals of the South African

Museum 5: 187-196.

BROOM, R. 1915. Catalogue of types and figured specimens of fossil vertebrates in the American

Museum of Natural History. If Permian, Triassic and Jurassic reptiles of South Africa. Bulletin of the

American Museum of Natural History 25: 105—164.

CHARIG, A. J. 1972. The evolution of the archosaur pelvis and hindlimb: and explanation in functional

terms. In: JOYSEY, K. A. & KEMP, T. S. eds. Studies in Vertebrate Evolution: 121-155.

Edinburgh: Oliver & Boyd.

CHARIG, A. J. & REIG, O. A. 1970. The classification of the Proterosuchia. Biological Journal of the

Linnean Society 2 : 125-171.

CHARIG, A. J. & SUES, H.-D. 1976. Suborder Proterosuchia Broom. /n: KUHN, O. ed. Handbuch der

Palaoherpetologie 13: 11-39. Stuttgart: Gustav Fischer Verlag.

CHENG, Z. W. 1980. Vertebrate fossils. Jn: Mesozoic stratigraphy and paleontology of the

Shan-Gan-Ning Basin 2: 114-171. Beijing: Publishing House of Geology.

CLARK, J.M., WELMAN, J.,. GAUTHIER, J. A. & PARRISH, J. M. 1993. The laterosphenoid bone of

early archosauriforms. Journal of Vertebrate Paleontology 13: 48-57.

COPE, E. D. 1869. Synopsis of the extinct Batrachia, Reptilia and Aves of North America. Transactions

of the American Philosophical Society 14: 1-252.

CRUICKSHANK, A. R. I. 1972. The proterosuchian thecodonts. Jn: JOYSEY, K. A. & KEMP, T. S.

eds. Studies in Vertebrate Evolution: 89-119. Edinburgh: Oliver & Boyd.

CRUICKSHANK, A. R. I. 1978. The pes of Erythrosuchus africanus Broom. Zoological Journal of the

Linnean Society 62: 161-177.

CRUICKSHANK, A. R. I. 1979. The ankle joint in some early archosaurs. South African Journal of

Science 75: 168-178.

EVANS, S. E. 1986. The braincase of Prolacerta broomi (Reptilia: Triassic). Neues Jahrbuch fur

Geologie und Paldontologie, Abhandlungen 173: 181—200.

EWER, R. F. 1965. The anatomy of the thecodont reptile Euparkeria capensis Broom. Philosophical

Transactions of the Royal Society of London (B) 248: 379-435.

GAUTHIER, J. A. 1986. Saurischian monophyly and the origin of birds. Memoirs of the California

Academy of Sciences 8: 1-55.

GOW, C. E. 1975. The morphology and relationships of Youngina capensis Broom and Prolacerta

broomi Parrington. Palaeontologia africana 18: 89-131.

GOWER, D. J. 1996. The tarsus of erythrosuchid archosaurs (Reptilia), and implications for early

diapsid phylogeny. Zoological Journal of the Linnean Society 116: 347-375.

GOWER, D. J. 1997. The braincase of the early archosaur Erythrosuchus. Journal of Zoology, London

242: 557-576.

GOWER, D. J. 1999. The cranial and mandibular osteology of a new rauisuchian archosaur from the

Middle Triassic of southern Germany. Stuttgarter Beitrdge zur Naturkunde (Serie B) 280: 1-49.

GOWER, D. J. 2000. Rauisuchian archosaurs (Reptilia, Diapsida): an overview. Neues Jahrbuch fir

Geologie und Paldaontologie, Abhandlungen 218: 447-488.

GOWER, D. J. 2001. Possible postcranial pneumaticity in the last common ancestor of birds and

crocodilians: evidence from Erythrosuchus and other Mesozoic archosaurs. Naturwissenschaften

88: 119-122

GOWER, D. J. & SENNIKOV, A. G. 1996a. Endocranial casts of early archosaurian reptiles.

Palaontologisches Zeitschrift 70: 579-589.

GOWER, D. J. & SENNIKOV, A. G. 19964. Braincase morphology in early archosaurian reptiles.

Palaeontology 39: 883906.

GOWER, D. J. & SENNIKOV, A. G. 1997. Sarmatosuchus and the early history of the Archosauria.

Journal of Vertebrate Paleontology 17 : 60-73.

GOWER, D. J. & SENNIKOV, A. G. 2000. Early Archosaurs from Russia. Jn: BENTON, M. J.,

KUROCHKIN, E. N., SHISHKIN, M. A. & UNWIN, D. M. eds. The age of dinosaurs in Russia and

Mongolia 140-159. London: Cambridge University Press.

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 77

GOWER, D. J. & WILKINSON, M. 1996. Is there any consensus on basal archosaur phylogeny?.

Proceedings of the Royal Society (B) 263: 1399-1406.

GREGORY, W. K. & CAMP, C. L. 1918. Studies in comparative myology and osteology, No. III.

Bulletin of the American Museum of Natural History 38: 447-563.

HUENE, F. VON. 1911. Uber Erythrosuchus, Vertreter der neuen Reptil-Ordnung Pelycosimia.

Geologische und Paldontologische Abhandlung 10: 1-60.

HUENE, F. VON. 1915. On reptiles of the New Mexican Trias in the Cope collection. Bulletin of the

American Museum of Natural History 34: 485-507.

HUENE, F. VON. 1920. Osteologie von Aétosaurus ferratus O. Fraas. Acta Zoologica 1: 465-491.

HUENE, F. VON. 1926. Gondwana-Reptilien in Sudamerika. Pal/aeontologia Hungarica 2: 1-108.

HUENE, F. VON. 1938. Stenaulorhynchus, ein Rhynchosauridae der ostafrikanischen Obertrias. Nova

Acta Leopoldina 6: 83-121.

HUENE, F. VON. 1946. Die grossen Stamme der Tetrapoden in den geologischen Zeiten. Biologische

Zentralblatt 65: 268-275.

HUENE, F. VON. 1960. Ein grosser Pseudosuchier aus der Orenburger Trias. Palaeontographica (A)

114: 105-111.

HUGHES, B. 1963. The earliest archosaurian reptiles. South African Journal of Science 59: 221-241.

IORDANSKY, N.N. 1973. The skull of the Crocodilia. In: GANS, C. & PARSONS, T. S. eds. Biology

of the Reptilia 4: 201—262. London: Academic Press.

JENKINS, F. A. 1971. Limb posture and locomotion in the Virginia opossum (Didelphis marsupialis)

and in other non-cursorial mammals. Journal of Zoology, London 165: 303-315.

JUUL, L. 1994. The phylogeny of basal archosaurs. Palaeontologia africana 31: 1-38.

KALANDADZE, N. N. & SENNIKOV, A. G. 1985. [New reptiles from the Middle Triassic of the

southern Cis-Urals.] Paleontologicheskii Zhurnal 1985: 77-84. [In Russian. ]

KITCHING, J. W. 1977. The distribution of the Karoo vertebrate fauna. Memoirs of the Bernard Price

Institute for Palaeontological Research 1: 1-131.

LY DEKKER, R. 1889. On associated remains of a theriodont reptile from the Karoo system of the Cape.

Proceedings of the Zoological Society of London 1889: 572-577.

LYDEKKER, R. 1890. Catalogue of the fossil Reptilia and Amphibia in the British Museum (Natural

History) Part 4. London: British Museum (Natural History).

MOOK, C. C. 1921. Notes on the postcranial skeleton in the Crocodilia. Bulletin of the American

Museum of Natural History 44: 67-100.

OCHEV, V. G. 1975. [On the proterosuchian palate. |’ Paleontologicheskii Zhurnal 1975: 98-105. [In

Russian. |

OCHEV, V. G. 1980. [New archosaurs from the Middle Triassic of the southern Cis-Urals.]

Paleontologicheskii Zhurnal 1980: 101—107. [In Russian. }

OCHEV, V. G. 1981. [On Erythrosuchus (Garjainia) primus Ochev.] Voprosy Geologii Yuzhnogo

Urala I Povolzh’ya 22: 3—22. [In Russian. ]

OCHEV, V. G. & SHISHKIN, M. A. 1988. Global correlation of the continental Triassic on the basis of

tetrapods. /nternational Geology Review 30: 163-176.

OSBORN, H. F. 1903. The reptilian subclasses Diapsida and Synapsida and the early history of the

Diaptosauria. Memoirs of the American Museum of Natural History 1: 449-507.

PARRISH, J. M. 1991. A new specimen of an early crocodylomorph (cf. Sphenosuchus sp.) from the

Late Triasic Chinle Formation of Petrified Forest National Park, Arizona. Journal of Vertebrate

Paleontology 11: 198-212.

PARRISH, J. M. 1992. Phylogeny of the Erythrosuchidae (Reptilia: Archosauriformes). Journal of

Vertebrate Paleontology 12: 93-102.

PARRISH, J. M. 1993. Phylogeny of the Crocodylotarsi, with reference to archosaurian and crurotarsan

monophyly. Journal of Vertebrate Paleontology 13: 287-308.

PENG, J. 1991. A new genus of Proterosuchia from Lower Triassic of Shaanxi, China. Vertebrata

Palasiatica 29: 95-107.

78 ANNALS OF THE SOUTH AFRICAN MUSEUM

PICKFORD, M. 1995. Karoo Supergroup palaeontology of Namibia and brief description of a

thecodont from Omingonde. Palaeontologia africana 32: 51-66.

REWCASTLE, S. C. 1980. Form and function in lacertilian knee and mesotarsal joints: a contribution to

the analysis of sprawling locomotion. Journal of Zoology, London 191: 147-170.

ROMER, A. S. 1922. The locomotion apparatus of certain primitive and mammal-like reptiles. Bulletin

of the American Museum of Natural History 46: 517-606.

ROMER, A. S. 1923. Crocodilian pelvic muscles and their avian and reptilian homologues. Bulletin of

the American Museum of Natural History 48: 533-552.

ROMER, A. S. 1942. The development of tetrapod limb musculature-the thigh of Lacerta. Journal of

Morphology 71: 251-298.

ROMER, A. S. 1971. The Chanares (Argentina) Triassic reptile fauna. XI. Two new long-snouted

thecodonts, Chanaresuchus and Gualosuchus. Breviora 379: \1—22.

SEELEY, H. G. 1894. On Euskelosaurus brownii (Huxley). Annals and Magazine of Natural History

14: 317-340.

SENNIKOV, A. G. 1995. [Early thecodonts of Eastern Europe.] Trudy Paleontologicheskogo Instituta

RAN 263: 1-141. [In Russian. ]

SERENO, P. C. 1991. Basal archosaurs: phylogenetic relationships and functional implications. Society

of Vertebrate Paleontology Memoir 2: \-53.

SERENO, P. C. & ARCUCCTI, A. B. 1990. The monophyly of crurotarsal archosaurs and the origin of

bird and crocodile ankle joints. Neues Jahrbuch fur Geologie und Palaontologie Abhandlung 180:

21-52.

SERENO, P. C. & NOVAS, F. E. (1993). The skull and neck of the basal theropod Herrerasaurus

ischigualastensis. Journal of Vertebrate Paleontology 13: 451-476.

SERENO, P. C. & WILD, R. (1992). Procompsognathus: theropod, ‘thecodont’ or both? Journal of

Vertebrate Paleontology 12: 435-458.

SHISHKIN, M. A. & OCHEV, V. G. 1995. [Significance of sections of southern Cis-Urals and East

European platform for global correlation of the continental Triassic on the terapods.] Jn:

SHISHKIN, M. A., OCHEV, V. G. & TVERDOKLEBOV, V. P. eds. [Biostratigraphy of the

Triassic of southern Cis-Urals|: 166-184. Moscow: Nauka. [In Russian. |

SHISHKIN, M. A. & WELMAN, J. 1994. A new find of Trematosuchus (Amphibia, Temnospondyl1)

from the Cynognathus zone of South Africa. Palaeontologia africana 31: 39-49.

SHUBIN, N. H. & SUES, H.-D. 1991. Biogeography of early Mesozoic Continental tetrapods: patterns

and implications. Paleobiology 17: 214—230.

SMITH, R. M. H. 1993. Vertebrate taphonomy of late Permian floodplain deposits in the southwestern

Karoo Basin of South Africa. Palaios 8: 45—67.

SNYDER, R. C. 1954. The anatomy and function of the pelvic girdle and hindlimb in lizard locomotion.

American Journal of Anatomy 95: |—46.

SUN, A.-L. 1980. Late Permian and Triassic terrestrial tetrapods of north China. Vertebrata PalAsiatica

18: 100—110. [In Chinese. ]

TATARINOYV, L. P. 1961. Materialy po pseudosukhiyam SSSR. Paleontologicheskii Zhurnal 1961:

117-132. [In Russian. ]

THULBORN, R. A. 1979. A proterosuchian thecodont from the Rewan Formation of Queensland.

Memoirs of Queensland Museum 19: 331-355.

WALKER, A. D. 1961. Triassic reptiles from the Elgin area: Stagonolepis, Dasygnathus and their allies.

Philosophical Transactions of the Royal Society of London (B) 244: 103-204.

WALKER, A. D. 1977. Evolution of the pelvis in birds and dinosaurs. Jn: ANDREW, S. M., MILES, R. S.

& WALKER, A. D. eds. Problems in vertebrate evolution: 319-357. London: Academic Press.

WALKER, A. D. 1990. A revision of Sphenosuchus acutus Haughton, a crocodylomorph reptile from

the Elliot Formation (late Triassic or early Jurassic) of South Africa. Philosophical Transactions of

the Royal Society of London (B) 330: 1-120.

WATSON, D. M.S. 1917. A sketch classification of the Pre-Jurassic tetrapod vertebrates. Proceedings

of the Zoological Society of London 1917: 167-186.

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 79

WELMAN, J. 1998. The taxonomy of the South African proterosuchids (Reptilia, Archosauromorpha).

Journal of Vertebrate Paleontology 18: 340-347.

WELMAN, J. & FLEMMING, A. 1993. Statistical analysis of skulls of Triassic proterosuchids

(Reptilia, Archosauromorpha) from South Africa. Palaeontologia africana 30: 113-123.

WELMAN, J., GROENEWALD, G. H. & KITCHING, J. W. 1991. Confirmation of the occurrence of

Cynognathus zone (Kannemeyeria-Diademodon Assemblage-zone) deposits (uppermost Beaufort

Group) in the northeastern Orange Free State, South Africa. South African Journal of Geology 94:

245-248.

WITMER, L. M. 1997. The evolution of the antorbital cavity of archosaurs: a study in soft-tissue

reconstruction in the fossil record with an analysis of the function of pneumaticity. Society of

Vertebrate Paleontology Memoir 3: |—73.

YOUNG, C. C. 1964. The pseudosuchians in China. Paleontologia Sinica 151: 1-205. [Chinese and

English. |

YOUNG, C. C. 1973. [On the occurrence of Vjushkovia in Sinkiang.] Memoirs of the Institute of

Vertebrate Paleontology and Paleoanthropology, Academia Sinica 10: 38—52. {In Chinese. ]

AMNH

BMNH

BPI

DMSW

GHG

IVPP

SAM

UMCZ

ANNALS OF THE SOUTH AFRICAN MUSEUM

ABBREVIATIONS

INSTITUTIONS

American Museum of Natural History

Natural History Museum, London

Bernard Price Institute for Palaeontological Research, Johannesburg

D.M.S. Watson Collection

Geological Survey, Pretoria

Institute of Vertebrate Paleontology and Paleoanthropology, Beijing

Nasionale Museum, Bloemfontein

Palaeontological Institute, Moscow

S.H. Rubidge Collection, Wellwood, Graaff Reinet

South African Museum, Cape Town

Cambridge University Museum of Zoology

Vienna Hoffmuseum

MORPHOLOGY

angular

accessory (3rd) rib head

acetabulum

acromion process

adductor crest

adductor fossa

area of origin of m. ambiens

antorbital fossa

anterior process of rib

articular

atlas neural arch

axis vertebra

basioccipital

basisphenoid

coronoid

capitulum

choana

chorda tympani branch of facial nerve, route of

cnemial crest

coracoid

coracoid foramen

surface finished with compacta bone

channel for olfactory tract

cultriform process of parasphenoid

dentary

dorsal part of ......

central posterior process of dentary

dorsal posterior process of dentary

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM

depression

(facet of) diapophysis

deltopectoral crest

ventral posterior process of dentary

epipterygoid

ectopterygoid

ectepicondylar groove

external naris

exoccipital

foramen for medial ethmoidal artery

frontal

fibula

foramen magnum

foramen/foramina

glenoid fossa of shoulder girdle

groove .

haemal arch

intercentrum

intercondylar groove

area of insertion of m. iliofibularis

area of insertion of m. iliofemoralis

infra-Meckelian foramen

intertrochanteric fossa

jugal

lacrimal

lamella

lacrimal foramen

lateral mandibular fenestra

laterosphenoid

maxilla

muscle attachment scar

ascending process of maxilla

Meckelian canal

thin lateral part of maxilla

thick medial part of maxilla

maxillary pit/neurovascular channel

maxillary pit for premaxillary peg

maxillary projection

nasal

nutrient foramina

nasal anteroventral flange

notch

obturator foramen

osteoderm

parietal

palatal process

(facet of) parapophysis

parabasal process

8&2

ANNALS OF THE SOUTH AFRICAN MUSEUM

postfrontal

pit for attachment of m. puboischiotibialis

pineal fossa

pit

palatine

premaxilla

premaxillary peg

postorbital

popliteal space

paroccipital process

postparietal

prearticular

prefrontal

prefrontal pillar

proatlas

pterygoid ramus of quadrate

pterygoid

parietal tubercle

posteroventral process of parietal

quadrate

quadrate head

quadratojugal

quadrate posterodorsal concavity

quadrate ramus of the pterygoid

right

retroarticular process

rib

surface/area/groove for articulation with ......

surangular

surangular foramen

scapula

supraoccipital

splenial

squamosal

supratemporal fenestra

supinator process

supinator ridge

area of mandibular symphysis

tibia

tubercle

tooth

transverse process

trochanter

‘tuck’ or ‘pleat’ in posterior margin of squamosal

tuberculum

ventral part of ......

tentative identification

metacarpal number

SAM—905

SAM-912

SAM-—978

SAM-1315

SAM-—3028

SAM-3612

SAM-—11330

SAM-—K 1098

SAM-K1118

SAM-—PK-K 10025

BPI 2094

BPI 2096

BPI 2529/322

BPI 2734

BPI 3893

BPI 4526

BPI 4539

BPI 4540

BPI 4553

BPI 4645

BPI 4649

BPI 4680

BPI 5207

GHG 7433MI

GHG AK82-22

NM QS1473

BMNH R533

BMNH R533a

BMNH R533b

BMNH R533c

BMNH R533d

BMNH R533e

BMNH R533f

BMNH R533¢

BMNH R533:

BMNH R533x

BMNH R533?

BMNH R2790

OSTEOLOGY OF ERYTHROSUCHUS AFRICANUS BROOM 83

APPENDIX I

Material of Erythrosuchus africanus

Incomplete postcranial skeleton (holotype).

Incomplete pelvic girdle.

Fragmentary skull material. A non-Erythrosuchus maxilla, probably not part of

the original specimen (different matrix), was also stored under this number.

Single cervical vertebra.

Incomplete postcranial material.

Incomplete braincase.

Skull roof fragments.

Incomplete left maxilla.

Incomplete posterior of skull and epistropheus.

Incomplete postcranial skeleton.

Fragmentary left maxilla.

Right pes, tarsus and distal crus.

Left maxilla.

Jaw fragments.

Virtually complete, largely unprepared skull.

Left premaxilla.

Fragmentary left maxilla.

Left maxilla.

First and fifth left metatarsal.

Posterior part of skull roof and incomplete braincase.

Fourth right metatarsal.

Extensive but incomplete skull, braincase, and postcranial material.

Complete skull.

Small partial skeleton, possibly a juvenile Erythrosuchus.

Incomplete skull roof.

Skull roof.

Two articulated dorsal vertebrae.

Neural arch of dorsal vertebra.

Incomplete dorsal vertebra.

Vertebral fragment.

Incomplete cervical vertebra.

Vertebral fragment.

Three consecutive caudal vertebrae.

Distal fragment of scapula.

Fragments of scapula and distal left femur.

Fragments of lower jaw and ilium.

Distal fragment of ulna.

Incomplete left mandible.

BMNH R2791

BMNH R2792

BMNH R2793

BMNH R2794

BMNH R2795

BMNH R2809

BMNH R3592

BMNH R3592a

BMNH R3755

BMNH R3759

BMNH R3762

BMNH R3763

BMNH R3764

BMNH R3776

BMNH R7888

ANNALS OF THE SOUTH AFRICAN MUSEUM

Single cervical vertebra.

Condylar fragment of left quadrate.

Vertebral fragments.

Dorsal part of quadrate and postcranial fragments.

Incomplete parietal posteroventral process and postcranial fragments.

Cast of left femur and tibia. Originals reportedly in Albany Museum,

Grahamstown, South Africa.

Incomplete, but extensive skull, mandible, and postcranial material of single

individual with at least some metacarpals from second, smaller individual.

Left distal crus, tarsus, and metatarsus (formerly DMSW R525).

Vertebral fragments.

Incomplete postcranial material, mostly vertebral but also proximal end of

eft femur.

‘Good but incomplete postcranial material. The specimen includes a distal

fragment of a humerus and a vertebra (with notochordal centrum) which are

not referable to Erythrosuchus.

Good right scapula and further fragmentary postcranial material.

Left pubis.

Neural arch fragments.

Two incomplete dorsal vertebrae.

Several specimens in the BMNH collection are unnumbered.

(1) Proximal fragment of left tibia, currently together with BMNH R2790, but not mentioned

by Seeley (1894).

(ii) Acervical and sacral vertebra and a sacral rib.

(111) Anterior fragment of iliac crest.

(iv) Complete right ilium.

BMNH R8667

UMCZ T666

UMCZ T675

UMCZ T678

UMCZ T682

UMCZ T700

AMNH 5594

AMNH 5595

AMNH 5596

AMNH 5597

Mid-dorsal vertebrae (formerly part of BMNH R3592)

Right ischium, formerly DMSW R389.

Single sacral rib, formerly DMSW R460.

Two anterior caudal vertebrae, formerly DMSW R488.

Isolated articular, formerly DMSW R520.

Crushed and poorly preserved braincase, formerly DMSW R417.

Incomplete skull roof.

Humeral fragments.

Scapula and coracoid.

Incomplete humerus and tibia.

None of these AMNH specimens were examined for this study.

—E a

— Se

— — ee ~ | emma ae —— _ eat es :

= 2 cy ; s a

. - a all — o Saar immanent tice ee, eee ee a ey — M

D . - z 5 ae eT —— a —— ny

° \ i r , = a ee eae Se ; — t -

— _ gl 5 ————

= - —_ aan deans ascent eS Fee <i =

™* — - I A TS ee ee ~

a = eee =

oO ee cat a Soeetentnetiiieemeennttiieensntined — ——

r nan commoner —< P =

Be ee

A _ {un

. 4)

Seti.

ANNALS OF THE SOUTH AFRICAN MUSEUM

ANNALE VAN DIE SUID-AFRIKAANSE MUSEUM

Volume 110 Band

August 2003 Augustus

Pantie Decl

UPPER CRETACEOUS (TURONIAN-CONIACIAN) AMMONITES

FROM SAO NICOLAU, ANGOLA

MICHAEL ROBERT COOPER

The South African Museum forms part of Iziko Museums of Cape Town