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(continued inside back cover)

ANNALS OF THE SOUTH AFRICAN MUSEUM

ANNALE VAN DIE SUID-AFRIKAANSE MUSEUM

Volume 89 Band

June 1982 Junie

Part 5 Deel

LOWER CRETACEOUS

(MIDDLE ALBIAN)

AMMONITES FROM

DOMBE GRANDE, ANGOLA

MICHAEL R. COOPER

Cape Town Kaapstad

The ANNALS OF THE SOUTH AFRICAN MUSEUM

are issued in parts at irregular intervals as material

becomes available

Obtainable from the South African Museum, P.O. Box 61, Cape Town 8000

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EDITOR/REDAKTRISE

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Kopieregnavrae aan die Suid-Afrikaanse Museum

ISBN 0 86813 036 2

Printed in South Africa by In Suid-Afrika gedruk deur

The Rustica Press, Pty., Ltd., Die Rustica-pers, Edms., Bpk.,

Court Road, Wynberg, Cape Courtweg, Wynberg, Kaap

LOWER CRETACEOUS (MIDDLE ALBIAN) AMMONITES FROM

DOMBE GRANDE, ANGOLA

MICHAEL R. COOPER

National Museum, Bulawayo

(With 31 figures)

[MS accepted 3 March 1982]

ABSTRACT

Two stratigraphically separated Middle Albian faunules, dominated by Douvilleiceras and

Oxytropidoceras respectively, are described from the environs of Dombe Grande. The wide

range of continuous variation within these assemblages has an important bearing on the

taxonomy of these forms. The phylogeny of the Mojsisovicziinae is discussed, and the following

new taxa are created: Mortoniceratoides gen. nov., Oxytropidoceras (Mirapelia) subgen. nov.

and O. (Benavidesites) subgen. nov. Middle Albian biostratigraphy outside the Boreal Realm is

discussed.

CONTENTS

PAGE

IntroductionS-c50 eee 265

Repionaligcolopyean- asses 267

SyStematics fee auc eet oe 270

Accvottheitaunatare nn rae eee 309

SUMMARY seein ee ea ae 312

Acknowledgements ............. 312

IReLeLenCeSey Henn cei Si)

INTRODUCTION

Choffat (in Choffat & De Loriol 1888) was the first to record ammonites

from the lower part of the Albian succession of Angola, describing and figuring

an ‘Acanthoceras’ mamillare (Schlotheim) (= Douvilleiceras mammillatum

aequinodum (Quenstedt)) (Choffat & De Loriol 1888: 71, pl. 3 (fig. 1)) from

the Dombe Grande area. The specimen was said to have come from the

‘Couches a Pholadomya pleuromyaeformis’, but as these beds are almost

certainly of Aptian age (Howarth 1965; Cooper 1976) this is an error. Howarth

(1965) described a small collection of Douvilleiceras made in 1930-1 by Alexan-

dre Borges from the Dombe Grande region, and recorded the species D.

mammillatum var. ?aequinodum (Quenstedt) and D. orbignyi Hyatt, thereby

suggesting the presence of upper Lower Albian (D. mammillatum Zone) strata.

Cooper (1976) described the bio- and lithostratigraphy of the region. The

present collections come from the immediate vicinity of Dombe Grande

265

Ann. S. Afr. Mus. 89 (5), 1982: 265-314, 31 figs.

ANNALS OF THE SOUTH AFRICAN MUSEUM

266

“speol judsoidas soul] UdyoOIg ‘polaquinu santRso] Sunosjyoo yyM ‘dew Ayypeoo7T “[ “34

> ay

Ni . PpUDAD aquog

LOWER CRETACEOUS AMMONITES FROM ANGOLA 267

(Fig. 1), and well above the beds containing Pholadomya pleuromyaeformis

Choffat.

Prefixes to catalogue numbers refer to material in the following

institutions:

BMNH British Museum (Natural History), London

NHMP Natural History Museum, Paris

OUM Oxford University Museum, Oxford

SAM South African Museum, Cape Town

USNMNH_ USS. National Museum of Natural History, Smithsonian Insti-

tution, Washington

Measurements are in millimetres, with dimensions, as a percentage of the

diameter, in parentheses.

REGIONAL GEOLOGY

The late Mesozoic succession in the Cuanza basin has been named the

Cuanza Group (Cooper 1976). At Dombe Grande in the extreme south of the

basin (12°54’S 13°13’E), the base of the Cuanza sequence is formed by the

Dombe Formation, a unit of coarse clastics and lagoonal deposits with inter-

bedded evaporites. The disconformably overlying transgressive deposits of the

‘Formacao com Pholadomya’ (Neto 1960, 1961) attain a thickness of about

100 m and comprise a basal member of oolitic limestones, calcarenites and

siltstones capped by calcareous siltstones rich in Pholadomya pleuromyaeformis

and other bivalves (Fig. 2C-F). Also present at this level are the echinoids

Salenia dombeensis De Loriol and Pygurus africanus De Loriol, and the

molluscs Neithea shawi Pervinquiere, Retusa malheiroi (Choffat), Panopea

gurgitis (Brongniart), Lithophaga praelonga (d’Orbigny), Nerita malheiroi

Choffat, ‘“Natica’ feioi Choffat, Actaeonella (Trochactaeon) cordeiroi (Choffat),

Actaeon lenzi Choffat, Ampullina (Pseudamaura) bulbiformis (J. Sowerby),

Pinna robinaldina dOrbigny, Cylindrites? delgadoi Choffat, and Tylostoma

peschueli Choffat.

Marine regression is reflected in the succeeding ‘Formagao com Nerinea’

(Fig. 1, locality 2), a lithologically highly variable unit spanning some 400 m

and comprising red and yellow lagoonal clastics yielding fossil wood, the

gastropods Nerinea capelloi Choffat (Fig. 3G-—H) and Cerithium monteiroi

Choffat, and an indeterminate ammonite (fide Neto 1961).

The ‘Formacao com Nerinea’ are overlain, perhaps disconformably, by

limestones and marls at the base of the Cuio Formation, the lower beds of

which have yielded the faunas described herein. The two assemblages, which

were picked up mainly as surface scree, are stratigraphically separated at

locality 4 (Fig. 1), with the Oxytropidoceras fauna occurring to the north-east

and thus from the younger beds. Upward the sequence becomes increasingly

unfossiliferous, and calcarenites and grits (Fig. 1, locality 1) span much of the

268 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 2. A-B. Puzosia bistricta (White), SAM-—PCA2649, x 1. C—F. Undetermined bivalves

from the ‘Couches a Pholadomya’, Reinecke Collection, South African Museum, X 1,5.

LOWER CRETACEOUS AMMONITES FROM ANGOLA

Fig. 3. A-B. Oxytropidoceras (Mirapelia) buarquianum (White), SAM-—PCAS5445, an individ-

ual transitional to douglasi morphotypes. C-D. Puzosia bistricta (White), SAM-PCA3474.

E. Inoceramus gr. anglicus Woods, SAM-PCA3443, from the Douvilleiceras assemblage.

F. Birostrina? cf. coptensis (Casey), SAM-PCA2664, from the Oxytropidoceras assemblage.

G-H. Nerinea capelloi Choffat. G. SAM-PCAS5S448, x 1,5. H. SAM-PCA5450, x 1,5. All

X 1 unless otherwise stated.

270 ANNALS OF THE SOUTH AFRICAN MUSEUM

remainder of the Middle Albian. These sediments are interpreted as reflecting

marine regression. The Cuio Formation attains a thickness of some 200 m and

is succeeded by bioclastic and oolitic limestones and calcarenites (Fig. 1,

localities 3, 6) yielding a low Upper Albian fauna including Prohysteroceras

wordiei Spath and Mortoniceras spp. This unit is to be correlated with the

Catumbela Member of the Cabo Ledo Formation to the north, reflecting the

early late Albian (Hysteroceras orbignyi Zone) transgression.

SYSTEMATICS

Subclass AMMONOIDEA Zittel, 1884

Family Douvilleiceratidae Parona & Bonarelli, 1897

Discussion

Since the lineage Procheloniceras — Cheloniceras — Eodouvilleiceras >

Douvilleiceras represents a single phyletic lineage, the subfamily Chelonicerati-

nae should be included in the synonymy of the nominate subfamily.

Subfamily Douvilleiceratinae Parona & Bonarelli, 1897

Genus Douvilleiceras de Grossouvre, 1894

Type species Ammonites mammillatus Schlotheim, 1813; subsequent designa-

tion of I.C.Z.N., Opinion 422, 1956

Discussion

Casey (1962: 260) has given a detailed diagnosis and discussion of this

genus, to which little may be added.

The genus Trinitoceras was erected (Scott 1940: 1016) for very large

douvilleiceratids in which the *. . . douvilleiceratid sculpture is evident up to or

beyond a diameter of 200 mm. Costae are multituberculate as in Douvilleiceras,

but the umbilical tubercles are greatly exaggerated in size, forming large bullae

on the umbilical margin at the ends of alternate costae. On later whorls costae

lose all trace of tuberculation but retain, irregularly, their alternate primary and

secondary arrangement. On the latest whorls shown, the ribs are nearly equal,

except that the occasional secondary (marked only by the fact that it does not

reach the umbilicus) is intercalated between the primaries. The whorl section,

degree of evolution, and the umbilical area do not differ greatly from like

features of well-known species of Douvilleiceras.’

It is clear from the above description that the genus Trinitoceras is based

upon the gigantic shells that accompany virtually all Douvilleiceras populations;

thus D. leightonense Casey, D. cheloniceratiforme Tavani, D. restitutum Ander-

son, and D. charshangense Mirzoyev are all typical Trinitoceras. However, the

fact that Trinitoceras and Douvilleiceras everywhere occur together as well as

the fact that they are indistinguishable in their early ontogenetic stages and

LOWER CRETACEOUS AMMONITES FROM ANGOLA Di

attain maturity at vastly different diameters, suggests to the writer that the

differences are those between sexual dimorphs. Trinitoceras is here considered

to be based upon Douvilleiceras macroconchs, and Casey (1962) is followed in

regarding it a synonym of Douvilleiceras.

Up to now almost fifty trivial names have been applied to Douvilleiceras;

these include D. mammillatum (Schlotheim) and its varieties paucicostatum

Parona & Bonarelli, praecox Casey, baylei Spath and aequinodum (Quenstedt),

D. inaequinodum (Quenstedt), D. pseudinaequinodum Collignon, D. orbignyi

Hyatt, D. clementinum (d’Orbigny), D. solitae (d’Orbigny), D. tarapacaense

Etayo-Serna, D. abozaglio Etayo-Serna, D. ivernoisi (Coquand), D. spiniferum

(Whiteaves), D. rex (Scott), D. reesidei (Scott), D. grandense (Scott),

D. adkinsi (Scott), D? dunlapi (Scott), D. quitmanense Scott, D. spathi Scott,

D. cuchillense Scott, D. muralense Stoyanow, D. aurarium Anderson, D. res-

titutum Anderson, D. offarcinatum (White), D. euzebioi (Maury), D. ser-

gipense Beurlen, D. multinodosum Hubach, D. benonae Besairie, D. spinosum

Tavani, D. albiense (Tavani), D. variabile Tavani, D. cheloniceratiforme Ta-

vani, D. scabrosum Casey, D. alternans Casey, D. pustulosum Casey, D. leigh-

tonense Casey and its variety pringlei Casey, D. magnodosum Casey,

D. subleightonense Mirzoyev, and D. charshangense Mirzoyev.

The extreme range of morphological variation exhibited by most assem-

blages is emphasized by the splitting of the British collections into fourteen taxa

(Casey 1962), those from Texas into eleven species (Scott 1940), and the

Somali collections into eight species (Tavani 1942, 1949), and this seems to

suggest genetic polymorphism. Thus Casey (1962: 263) has noted that all the

mostly endemic species of Douvilleiceras recorded from southern England ‘. . .

come from a limited range of strata and they constitute a closely interconnected

plexus that in former days would have been interpreted (perhaps correctly) as

one very large, highly variable species’. Unfortunately Casey’s revision, coming

at a time when it was the practice to base species on very narrowly defined

limits, suffers from oversplitting, since recent studies of ammonite populations

(Kennedy & Cobban 1976) suggests that such variation is not extraordinary. In

addition, Mirzoyev (1967: 54) has also commented that ‘... all species of

Douvilleiceras are closely interrelated and could have been treated as a single

very extensive and varied species; but investigators concerned with this group

of ammonites have made efforts to discover differences, based entirely on the

frequency, degree of development and modifications of the conch sculpture in

the course of its development’.

Casey (1962), in his revision of the British species of Douvilleiceras, laid

much emphasis on the width of the ventral sulcus, number of notches per rib,

and the ontogenetic stage at which ornament change occurred as taxonomic

criteria. However, many writers have noted that the number of notches

increases with diameter, while Collignon (1963), Mirzoyev (1967), and

McLearn (1972) have all reported specimens with different numbers of notches

on opposing flanks. Consequently, this criterion is considered to be of very

Dif?) ANNALS OF THE SOUTH AFRICAN MUSEUM

limited taxonomic significance, if at all. Both the width of the ventral sulcus and

the ontogenetic stage at which morphological changes occur are relative charac-

ters that are unlikely to stand up to population analysis, especially when it is

considered that many of the taxa so defined are contemporaneous, occurring

together in the same bed. As such, the writer believes Douvilleiceras to display

genetic polymorphism and thus high intraspecific variability.

Stratigraphically Douvilleiceras ranges from the top of the Leymeriella

tardefurcata Zone (Leymeriella regularis Subzone) into the lower part of the

Middle Albian (Lyelliceras lyelli Subzone of the Hoplites dentatus Zone).

During this period it attained a cosmopolitan distribution and is currently

reported from North America (British Columbia, California, Arizona, Texas,

New Mexico), South America (Peru, Columbia, Brazil), Africa (Gabon,

Angola, Zululand, Mozambique, Somalia), Madagascar, Asia (eastern Carpa-

thians, northern Caucasus, western and central Kopet Dag, Bol’shoy Balkhan,

Tuarkyr, Mangyshlak, Badkhiz Islands, southern Gissar Range, Afghanistan),

Europe (southern England, France, Switzerland, ?Germany, Poland, Bulga-

ria), and Japan.

Douvilleiceras mammillatum aequinodum (Quenstedt, 1849)

Figs 4A-B, 6C-G, 7D, G-I, 8A-B, 9A-C, E, 10C—D, F-H, 12A-B, 17A

Ammonites monile aequinodus Quenstedt, 1849: 137, pl. 10 (fig. 2).

? Ammonites offarcinatus White, 1887: 219, pl. 23 (fig. 4 only).

Acanthoceras mammillare (Schlotheim) Choffat (in Choffat & De Loriol), 1888: 71, pl. 3

(fig. 1).

Douvilleiceras monile var. aequinodum (Quenstedt) Breistroffer, 1947: 65.

? Douvilleiceras cheloniceratiforme Tavani, 1949: 38, pl. 8 (fig. 6).

? Douvilleiceras monile (J. Sowerby) Benavides-Caceres, 1956: 442, pl. 43 (figs 1-4).

? Douvilleiceras restitutum Anderson, 1938: 175, pl. 54 (fig. 2).

Douvilleiceras mammillatum var. aequinodum (Quenstedt) Casey, 1962: 271, pl. 40 (fig. 5),

pl. 41 (figs 5-7), pl. 42 (fig. 10), figs 94a-c, 95a—b, 102d, 103a—b. Howarth, 1965: 343, pl. 1

(figs 1-4).

? Douvilleiceras albense Spath, Collignon, 1963: 112, pl. 284 (fig. 1243).

Douvilleiceras sp. B, Beurlen, 1970: 460, pl. 4 (figs 3-4), figs 16-17.

? Douvilleiceras spinifer'um (Whiteaves) McLearn, 1972: 62, pl. 28 (fig. 1 only).

Douvilleiceras cf. mammillatum (Schlotheim) Young, 1974: 184, pl. 4 (figs 1, 3, 6).

Material

Fifty-seven specimens, SAM-—PCA2639, 3409, 3417, 3427, 3429-3431,

3434, 3439-3440, 3442, 3456, 3459-3460, 3462-3464, 3467, 3469, 3471-3473,

3476-3480, 3482, 3484-3487, 3490-3491, 3493-3494, 3499, 3501, 3503,

3509-3511, 3516-3518, 3520, 3522-3523, 3526-3527, 3529-3530, 3532, 3534,

and 3536, all preserved as limestone steinkerns.

Description

This taxon is the most abundant component of the Douvilleiceras fauna,

although many of the specimens are fragmentary and most are more or less

eroded, having been picked up as surface scree. This erosion gives a number of

LOWER CRETACEOUS AMMONITES FROM ANGOLA 273

Fig. 4. A-B. Douvilleiceras mammillatum aequinodum (Quenstedt), SAM—PCA3434. C-D, F.

Douvilleiceras inaequinodum (Quenstedt). C-D. SAM-PCA3435, a juvenile showing very fine

intercalated ribs. F. SAM-PCAS5451, a badly eroded fragment showing three intercalated ribs

between main ribs. E. Nerinea capelloi Choffat, SAM-PCA5449, x 1,5. G. Douvilleiceras

variabile Tavani, SAM-PCA3448. All x 1 unless otherwise stated.

274 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 5. A-B. Oxytropidoceras (Oxytropidoceras) roissyanum (d’Orbigny). The original of

D’Orbigny’s (1841) protograph, NHMP. C—D. Douvilleiceras mammillatum mammillatum

(Schlotheim). The neotype, BM—C12491. Both x 1. Photos: W. J: Kennedy.

LOWER CRETACEOUS AMMONITES FROM ANGOLA LYS

specimens the appearance of having had very much narrower ribs than, in fact,

they probably had.

The shell is moderately evolute (umbilicus 32,5-39% of the diameter),

with rather inflated whorls, and a subreniform depressed whorl section. In all

the better preserved material the ventral sulcus is, or appears to have been,

rather narrow. The number of notches to each rib varies with ontogeny, with

about 5 at 30 mm diameter increasing to 8-9 at about 60 mm diameter. Up to

about 40 mm diameter the ribs tend to be simple, distant and rursiradiate,

commonly with 10-14 ribs per half whorl. However, several of the more

densicostate juveniles have 16 ribs per half whorl. Beyond this diameter

intercalation and bifurcation becomes increasingly common, generally with

16-20 rather uniform ribs per half whorl. One individual, SAM-PCA3417,

retains simple ribbing to 62 mm diameter, whereas SAM—PCA3431 has very

fine, nontuberculate intercalatories between main ribs at about 40 mm di-

ameter, only to loose them with further growth. The tuberculation of this

subspecies is very reduced, typically with the lateral tubercle subdued and

bullate. In SAM—PCA3472, however, main ribs bear a prominent lateral

tubercle and, up to 35 mm diameter, alternate with fine nontuberculate interca-

latories. Beyond this diameter all the ribbing becomes uniform and the lateral

tubercule is much reduced and bullate. In SAM—PCA3435, the early whorls are

strongly tuberculate and distantly ribbed but, at 47 mm diameter, there is a

sudden and dramatic reversion to normal aequinodum-type ornament. SAM—

PCA3430 connects typical aequinodum-type morphologies to the large macro-

conch fragments (SAM-—PCA3408, 3410-3411, 3414, 3425, 3433, 3465, 3483,

3500) in the collection.

Measurements

No D H W W/H U

SAM-PCA3427 Ws 29 34 29569)

SAM-PCA3429 83 35 45 LS) PAY (EPA)

SAM-PCA3431 ? 82, 3i/ LENG ?

SAM-PCA3434 70 26 32 DS (8s)

SAM-—PCA3527 51 19 Dil Petit 18 (35,3)

Discussion

Quenstedt (1849) described two species of Douvilleiceras, D. aequinodum

and D. inaequinodum. Since the latter species is typically lower Middle Albian

(Casey 1962), it may be reasonable to assume this is also the level of D. aequi-

nodum. Such a supposition tends to be supported by their coexistence in the

eodentatus Nodule Bed (Bed e of Destombes et al. 1977) (Fig. 12A—D, G-H) at

Bully, Pays de Bray, France, and also in Angola. Since the Angolan D. mam-

millatum material is dominated by aequinodum morphotypes, with no

undoubted individuals of D. mammillatum s.s. (Fig. 5C-D), it seems reason-

able to assume that a genuine shift in population structure has occurred when

276 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 6. A. Douvilleiceras inaequinodum (Quenstedt), SAM—PCA3535, a juvenile. B. Oxytro-

pidoceras (Mirapelia) buarquianum (White), SAM-PCA3765, a typical juvenile. C-G. Dou-

villeiceras mammillatum aequinodum (Quenstedt). C. SAM—PCA3427. D-E. SAM-—PCA2639.

F-G. SAM-PCA3431. All x 1.

LOWER CRETACEOUS AMMONITES FROM ANGOLA

Fig. 7. A-C. Douvilleiceras inaequinodum (Quenstedt). A. SAM-PCA3466. B-C. SAM-—

PCA3437, a typical example. D, G-I. Douvilleiceras mammillatum aequinodum (Quenstedt).

D. SAM-PCA3479. G. SAM-PCA3481. H-I. SAM-PCA3527, a typical juvenile with fine,

distant, simple ribs. E-F. Douvilleiceras variabile Tavani, SAM—PCA3496. All x 1.

278 ANNALS OF THE SOUTH AFRICAN MUSEUM

compared with the typical mammillatum Zone assemblages of D. mammillatum

(cf. Casey 1962). It is for this reason, and because D. aequinodum can arguably

be regarded as typically Middle Albian, that the writer has used Quenstedt’s

name at subspecific level. As noted by Casey (1962) aequinodum morphotypes

are also abundant in the mammillatum Zone of England, but at this level

coexist with, and are connected by transitions to, D. mammillatum s.s.,

D. mammillatum var. praecox Casey, and D. monile (J. Sowerby). Since there

is, in the writer’s opinion, but a single biological taxon involved in the latter

list, the various nominal forms are merely morphotypes within a single poly-

typic species. Disregarding the nomenclatural problems, it is clear that the

Angolan population of D. mammillatum is substantially different from that at

Copt Point, Folkestone, and thus warrants subspecific distinction.

Both Douvilleiceras restitutum Anderson and D. cheloniceratiforme are

based upon macroconchs whose inner whorls suggest they may belong here.

Similarly, the hypotype of D. spiniferum (Whiteaves) figured by McLearn

(1972, pl. 28 (fig. 1)) also shows few features to distinguish it from typical

aequinodum morphotypes. In addition, one of White’s (1887, pl. 23 (fig. 4))

syntypes of D. offarcinatum shows a rib density that suggests possible reference

to Quenstedt’s taxon.

Douvilleiceras variabile Tavani, 1949

Figs 4G; 7E-F; 8C_D) 9G, 11C_—De ISAn IS, 22

Ammonites mammillaris Schlotheim, d’Orbigny, 1841: 249, pl. 72 (fig. 5 only).

Douvilleiceras variabile Tavani, 1949: 37, pl. 10 (figs 1-2).

? Douvilleiceras pseudinaequinodum Collignon, 1963: 120, pl. 288 (fig. 1249).

Douvilleiceras monile (J. Sowerby) Collignon, 1963: 118, pl. 287 (fig. 1248).

Douvilleiceras aff. baylei Spath, Collignon, 1963: 118, pl. 287 (fig. 1247).

Douvilleiceras subleightonense Mirzoyev, 1967: 59, pl. 8 (figs 1-3).

? Douvilleiceras sp. B, McLearn, 1972: 67, pl. 13 (fig. 1), pl. 16 (fig. 1).

Material

Four specimens, SAM—PCA3422, 3447-3448 and 3496, all preserved as

internal moulds.

Description

In shell form, this species is very similar to the last but with substantially

different ornament. In the Angolan material, ornament comprises well-

developed main ribs ornamented with a distinct umbilical tubercle, a pro-

nounced mid-lateral tubercle and bullate ventral tubercles that weaken beyond

about 45 mm diameter and are lost at about 60 mm diameter. At about this

stage a small tubercle also appears between the umbilical and mid-lateral

tubercle, and the ventral tubercles bear three notches. There are, therefore,

eight notches per rib. Between these long ribs are invariably one, sometimes

two intercalatories that do not connect with the umbilicus and lack mid-lateral

tubercles. These ribs tend to be somewhat finer than the main ribs and give rise

to the typical ‘variable’ ornament of this species.

LOWER CRETACEOUS AMMONITES FROM ANGOLA 279

Fig. 8. A-B. Douvilleiceras mammillatum aequinodum (Quenstedt), SAM-PCA

3429. C-D. Douvilleiceras variabile Tavani, SAM-PCA3447. Note the alternating

long and short ribs and prominent lateral tubercle typical of this species. Both x 1.

280 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 9. Whorl sections of Douvilleiceras. A-C, E. Douvilleiceras mammillatum aequinodum

(Quenstedt). A. SAM-PCA3417. B. SAM-—PCA3433. C. SAM-PCA3479. E. SAM-PCA

3431. D, F, H. Douvilleiceras inaequinodum (Quenstedt). D. SAM—PCA3535. F. SAM-—

PCA3437. H. SAM-PCA 3466. G. Douvilleiceras variabile Tavani, SAM-PCA3496. All x 1.

LOWER CRETACEOUS AMMONITES FROM ANGOLA 281

Measurements

No D H W W/H U

SAM-PCA3496 51 19 22 1,16 19 (37)

Discussion

Douvilleiceras variabile Tavani seems to be based upon the inner whorls of

a macroconch, showing the irregular ornament of the early growth stages, with

1-2 weak ribs between main ribs, and the more regular ornament of the

macroconch on the adoral half of the last whorl. Tavani’s (1949) species is

undoubtedly very close to D. mammillatum (Schlotheim), and D’Orbigny’s

(1841, pl. 72 (fig. 5)) Ammonites mammillaris seems to be a typical example of

this species. Indeed, even in the present collection, several individuals seem to

combine the characters of D. variabile and D. mammillatum aequinodum

(Fig. 15E). This tends to suggest that D. variabile is merely another morpho-

type within a polytypic D. mammillatum. While this is the writer’s belief,

opposition to the gross ‘lumping’ that such synonymies would involve from one

of the referee’s of this paper has led to the adoption of a somewhat more

cautious approach. Douvilleiceras variabile is here maintained as a distinct

species because the writer does not believe in sympatric subspecies.

Douvilleiceras subleightonense Mirzoyev is a gigantic macroconch attaining

some 600 mm diameter, whose inner whorls show the irregular ribbing typical

of this species, and it may reasonably be included here. The Douvilleiceras sp.

B of McLearn (1972, pl. 13 (fig. 1), pl. 26 (fig. 1)) is another macroconch that

may belong here. Yet another macroconch whose inner whorls are reminiscent

of this species is D. pseudinaequinodum Collignon. Douvilleiceras ivernoisi

(Coquand) (Pictet & Renevier, 1854, pl. 2 (fig. 1)) is somewhat similar to

D. variabile, but lacks the pronounced lateral tubercle.

Douvilleiceras inaequinodum (Quenstedt, 1849)

Figs 4C-D, F, 6A, 7A-C, 9D, F, H, 10E, 11A, 12C-D, G-H

Ammonites mammillaris Schlotheim, d’Orbigny, 1841: 249, pl. 73 (figs 1-3 only).

Ammonites monile inaequinodus Quenstedt, 1849: 138, pl. 10 (fig. 1).

Douvilleiceras inaequinodum (Quenstedt) Parona & Bonarelli, 1897: 95, pl. 4 (fig. 6), pl. 13

(fig. 6). Collignon, 1950: 46, fig. 2; 1963: 114, pl. 285 (fig. 1245). Casey, 1962: 282,

fig. 95c.

Douvilleiceras orbignyi Hyatt, 1903: 110. Casey, 1962: 279, pl. 40 (figs 6-8), pl. 42

(figs. 12-13). Howarth, 1965: 345, pl. 1 (fig. 5).

Douvilleiceras mammillatum var. baylei Spath, 1923: 70, pl. 5 (fig. 4).

Douvilleiceras aff. inaequinodum (Quenstedt) Spath, 1923: 73, pl. 4 (fig. 5).

? Douvilleiceras cf. inaequinodum (Quenstedt) Scott, 1937: 35, pl. 6 (figs 3-4), fig. 1.

Douvilleiceras alternans Casey, 1962: 282, pl. 42 (fig. 1), fig. 1021.

? Douvilleiceras magnodosum Casey, 1962: 284, pl. 42 (fig. 4), fig. 102k.

? Douvilleiceras charshangense Mirzoyev, 1967: 54, pl. 7 (figs 1-5).

? Douvilleiceras sp. A, McLear, 1972: 67, pl. 12 (fig. 1).

Douvilleiceras cf. orbignyi Hyatt, Young, 1974: 188, pl. 5 (figs 9-10).

282 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 10 A-B. Oxytropidoceras (Mirapelia) buarquianum (White), SAM-—PCA2656, a douglasi

morphotype which very closely approaches O. mirapelianum (d’Orbigny), x 0,75. C—-D, F-H.

Douvilleiceras mammillatum aequinodum (Quenstedt). C. SAM-—PCA3494. D. SAM-PCA

3503. F. SAM-PCA3527. G. SAM-PCA3499. H. SAM-PCA3518. E. Douvilleiceras inae-

quinodum (Quenstedt), SAM—PCA3504. All x 1 unless otherwise stated.

LOWER CRETACEOUS AMMONITES FROM ANGOLA

“<

GGL OIE ee,

~ i

tas iaaaicr |

~tameatapes 3

a ini }

Fig. 11. A. Douvilleiceras inaequinodum (Quenstedt), SAM-PCA3458, a specimen showing

the increased number of intercalatories in maturity. B. Oxytropidoceras (Mirapelia) sergipense

(White). Front view of SAM—-PCA5444. C-D. Douvilleiceras variabile Tavani, SAM-PCA3422.

E. Plagiostoma sp., SAM-PCA5490, from the Oxytropidoceras assemblage. All x 1.

284 ANNALS OF THE SOUTH AFRICAN MUSEUM

Material

Eighteen specimens, SAM—PCA3435-3438, 3444, 3451, 3453, 3456-3458,

3466, 3492, 3495, 3498, 3504, 3512, 3525, and 3535, all preserved as limestone

steinkerns.

Description

This is a rather common species in the Angolan fauna. The shell is generally

moderately evolute, inflated, with a subreniform, depressed whorl section. The

umbilicus is rather wide, with steep umbilical walls and well-rounded shoulders.

Ornament comprises sparse, distant, slightly rursiradiate ribs, which are

narrower than the interspaces and alternate weak and strong. The strong main ~

ribs are ornamented with small umbilical tubercles, a prominent lateral tubercle,

and exaggerated ventral bulges, each with three spiral notches. In juveniles, only

two spiral notches are present on the ventral bulges. With ontogeny, a small

tubercle appears between the umbilical and mid-lateral tubercle and another

between the latter and the ventrolateral bulges. Thus, there may be up to eight

crenulations per rib in adults. The fine intercalated ribs, usually one and rarely

two, between main ribs generally lack discernible ornament (on the weathered

internal moulds), but in some individuals develop a small but distinct mid-lateral

tubercle. In the early growth stages (Figs 4C-D, 12G—H) the intercalated ribs

may be absent or so fine that there is difficulty in distinguishing this species from

D. mammillatum s.s. There are probably about 7-8 main ribs per half whorl. The

ventral sulcus is moderately broad and rather deep.

Discussion

Casey (1962) considered D. inaequinodum to be a typical Middle Albian

species, distinguished from the earlier D. orbignyi Hyatt and D. alternans

Casey in having two, not one, fine intercalatories between main ribs. However,

material from the /sohoplites eodentatus nodule bed at Bully, Pays de Bray,

France (Fig. 12C—D), shows that at least some individuals of D. inaequinodum

have but a single fine intercalated rib between main ribs. In view of this, and

because Casey (1962) has noted transitions between D. alternans and D. orbig-

nyi, the latter two species are included in the synonymy of D. inaequinodum.

Until the population structures of the mammillatum Zone assemblages are

better known, it is perhaps prudent to retain orbignyi as a subspecies for these

forms, as D. inaequinodum orbignyi Hyatt.

Family Anisoceratidae Hyatt, 1900

Genus Protanisoceras Spath, 1923

Type species Hamites raulinianus d’Orbigny, 1842; by original designation

Protanisoceras sp.

Fig. 13B

Material

A single fragment, SAM-—PCA3461, preserved as a limestone steinkern

from the Douvilleiceras assemblage.

LOWER CRETACEOUS AMMONITES FROM ANGOLA 285

Fig. 12. Douvilleiceras spp. from the I. eodentatus Nodule Bed, Bully, Pays de Bray, France

(Bed e of Destombes et al. 1977). A-B. Douvilleiceras mammillatum aequinodum (Quen-

stedt), OUM-KZ976. C-D, G-—-H. Douvilleiceras inaequinodum (Quenstedt). C-D.

OUM-KZ982. G-H. OUM-KZ981. E-F. Douvilleiceras mammillatum mammillatum

(Schlotheim), OUM-KZ979. All x 1.

286 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 13. A. Douvilleiceras variabile Tavani, SAM-PCA3472. B. Protanisoceras sp., SAM-

PCA3461. C—D. Venezoliceras acostae (d’Orbigny), syntypes. in the D’Orbigny Collection,

NHMP. E-F. Mortoniceratoides rigidus (Spath), the holotype, BM—C34879. All x 1.

LOWER CRETACEOUS AMMONITES FROM ANGOLA 287

Fig. 14. A-C. Puzosia bistricta (White), the lectotype, designated herein, USNMNH 12102,

from Porto dos Barcos, Mariom, Sergipe, Brazil. D-E. Oxytropidoceras (Mirapelia) mirapelia-

num (d’Orbigny), NHMP-5758, in the D’Orbigny Collection, from Clar, France. F-G.

Oxytropidoceras (Oxytropidoceras) carbonarium (Gabb), the holotype of O. cantianum Spath,

BM-C12501, from the D. cristatum Zone at Folkestone.

288 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 15. A-B. Oxytropidoceras (Mirapelia) buarquianum (White), the lectotype, designated

herein (after White 1887). C-—D. Puzosia bistricta (White), copy of White’s (1887) original

illustration. E. Douvilleiceras cf. variabile Tavani, SAM—PCA3435. Note the abrupt change

from a variabile to an aequinodum-type ornament. All x 1.

LOWER CRETACEOUS AMMONITES FROM ANGOLA 289

Description

The short curved fragment gives the impression of having had a com-

pressed, elliptical whorl section. Ornament comprises rather broad, low, rursi-

radiate ribs, wider than the interspaces, each bearing a distinct ventrolateral

tubercle. There are about three ribs in a distance equal to the whorl height.

Discussion

The available specimen is too fragmentary to warrant comparison with the

many described species of Protanisoceras, but does provide the first record of

this genus from Angola.

Family Desmoceratidae Zittel, 1895

Subfamily Puzosiinae Spath, 1922

Genus Puzosia Bayle, 1878

Type species Ammonites mayoriana d’Orbigny, 1842

(= replacement name for A. planulatus J. de C. Sowerby

non Schlotheim 1820 nec Schuebler 1830);

by subsequent designation

Puzosia bistricta (White, 1887)

Figs 2A-B, 3C-D, 14A-C, 15C-D, 16, 17B-C, 18C-D, 19A-B

Ammonites bistrictus White, 1887: 216, pl. 23 (figs 5-8).

Ammonites hopkinsi Forbes, White, 1887: 213, pl. 21 (figs 1-3), pl. 22 (fig. 5).

Puzosia welwitschia Choffat (in Choffat & de Loriol), 1888: 68, pl. 2 (fig. 4).

Puzosia garajauana Maury, 1930: 289; 1936: 234, pl. 20 (figs 1-3). Beurlen, 1970: 446, pl. 1

(figs 1-3), figs 1-2.

Puzosia rosarica Maury, 1936: 236, pl. 26 (figs 2-3). Beurlen, 1970: 446, pl. 1 (figs 4-5),

figs 3-6.

Material

Thirty specimens, SAM—PCA2623, 2625-2626, 2636, 2638, 2649, 2652,

2660-2661, 3412, 3415-3416, 3419-3421, 3424, 3426, 3429, 3432, 3434, 3449,

3452, 3474-3475, 3635, 3749, 3751, 3753, 3757, all preserved as limestone

steinkerns and mostly from the beds with Douvilleiceras.

Description

Shell moderately large, compressed, with a moderately narrow umbilicus

(21-27 % of the diameter). The umbilical walls are steep, with evenly rounded

shoulders, and the flanks slightly convex, almost flat. Maximum width is just

below mid-flank and the whorl section (Fig. 16) is elliptical. There are generally

about 7-8 straight, prorsiradiate constrictions per whorl, which flex forward just

before crossing the venter. Characteristically, the whorls show an increase in

inflation immediately after a constriction. The constrictions are broad and

shallow, typically with a peculiar wedge-shaped rib intercalated across the

290 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 16. Whorl sections of Puzosia bistricta (White). A. SAM-—PCA2626.

B. SAM-PCA3412. Both x 1.

venter in the middle growth stages. Because of the nature of preservation, the

true characters of the ribbing are difficult to assess. They first appear on the

outer parts of the flanks at about 60-80 mm diameter, and coarsen and become

more prominent across the venter with age. On SAM-—PCA2623 there are

twenty fine ribs between successive constrictions whereas on SAM—PCA2649

there are only seven.

Discussion

Puzosia welwitschia Choffat is clearly conspecific with the Ammonites

hopkinsi figured by White (1887), which was later renamed Puzosia garajauana

by Maury (1930). They almost certainly merely represent the middle and adult

growth stages, respectively, of P. bistricta (White) (Fig. 14A—-C). Puzosia

rosarica Maury occurs with P. bistricta and is based upon juvenile material

which probably does not warrant specific separation. There are few species of

Puzosia with which this highly distinctive Middle Albian species may be

confused.

Family Brancoceratidae Spath, 1933

Subfamily Mojsisovicziinae Hyatt, 1903

Genus Oxytropidoceras Stieler, 1920

Type species Ammonites roissyanus d’Orbigny, 1841;

by original designation

Discussion

The most comprehensive treatment of this genus is that of Young (1966).

He included Androiavites Collignon (1936) in the synonymy of Adkinsites and

provided the following emended diagnosis of Manuaniceras: ‘Ammonites with

LOWER CRETACEOUS AMMONITES FROM ANGOLA 291

few whorls, which are much higher than wide; there are many flat ribs at some

stage in the ontogeny, and ribs may be single or bifurcating at one or more

positions at the umbilicus or on the flank’ (p. 95).

Unfortunately, however, flat-topped ribs are not a feature of Manuaniceras

manuanense (Spath) (Fig. 31B) and hence cannot be used in the formulation of

a diagnosis of this taxon. As Young (1966) rightly pointed out, Manuaniceras is

a direct descendant of the Oxytropidoceras roissyanum group, which mainly

differs in showing rib bifurcation at various levels on the flank. The differences

are slight and the writer finds little use for the genus/subgenus Manuaniceras

which is here included in the synonymy of Oxytropidoceras s.s.

As noted by Young (1966), and is clear both from the stratigraphic record

and described species of Oxytropidoceras, the history of this taxon is one of

parallel evolution between two species groups. The O. mirapelianum

(d’Orbigny) (Fig. 14D-E herein) plexus comprises O. mirapelianum

(d’Orbigny), O.evansi (Spath), O. douglasi Knetchel, O. buarquianum

(White), O. sergipense (White), O. packardi Anderson, O. boulei Collignon,

O. paucituberculatum (Collignon), and O. colcanapi Collignon. These are all

coarsely ribbed species without bifurcation or intercalation of the simple ribs.

To this group the writer would assign the strongly derived species of O. salasi

Young, O. stenzeli Young, and O. pandalense Young in which the adult whorls

become densicostate, with occasional bifurcation and intercalation, and thus

homoeomorph ‘Manuaniceras’. The other species group is that of O. roissya-

num (d’Orbigny) in which the ribs are fine, with frequent bifurcation at or

above the umbilical edge, and which includes all the described ‘Manuaniceras’

species of Young (1966). Since these two plexi appear almost simultaneously at

the base of the Middle Albian (Owen 1971) and evolved in parallel until their

final extinction in the early late Albian, the writer believes they merit sub-

generic distinction. The writer proposes, therefore, the new subgenus

Oxytropidoceras (Mirapelia) to include all those coarse-ribbed species assigned

to the mirapelianum plexus above, with Ammonites mirapelianus d’Orbigny as

type species. Oxytropidoceras (Mirapelia) sergipense (White) provides the root-

stock from which the typical coarse-ribbed species of Venezoliceras (of which

Tarfayites Collignon (1966) is a synonym), such as V. venezolanum (Stieler),

V. acostae (d’Orbigny) (Fig. 13C-D), V. heueri Young, V. obscurum Young,

V. texanum Young, V? chihuahuaense (Bose), V. kiowanum (Twenhofel), V.

umsinenense (Van Hoepen), V. bituberculatum (Collignon), V. madagasca-

riense (Collignon), V. robustum (Renz) and V. clavicostatum (Renz), are

derived. However, as noted by Young (1966) and Renz (1968), there is a

second group of Venezoliceras, typified by Venezoliceras harrisoni

Benavides-Caceres, in which the early and middle growth stages show dense,

bifurcating, nontuberculate ribbing, with a flank tubercle developed only at

relatively large diameters. This group, which also includes V. acutocarinatum

(Shumard), V. multicostatum (Renz), V. intermedium (Renz), and V. karsteni

(Stieler), seems to have its ancestry in ‘Manuaniceras’ and, as such, its similar-

292 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 17. A. Douvilleiceras mammillatum aequinodum (Quenstedt), SAM—PCA3423, a macro-

conch fragment, X 0,67. B-C. Puzosia bistricta (White), SAM—PCA5447, x 1.

LOWER CRETACEOUS AMMONITES FROM ANGOLA 293

Fig. 18. A-B. Oxytropidoceras (Mirapelia) sergipense (White), SAM-—PCAS5444. C-D. Puzo-

sia bistricta (White), SAM—PCA3420. Both x 1.

294 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 19. A-B. Puzosia bistricta (White), a specimen in the South African Museum. C-E.

Oxytropidoceras (Mirapelia) buarquianum (White). C. SAM—PCAS5446, a douglasi morpho-

type. D-E. SAM-PCA3603, a salasi morphotype. All x 1.

LOWER CRETACEOUS AMMONITES FROM ANGOLA 295

ity to the V. acostae group is due to convergence. Consequently, the writer

proposes the new subgenus Oxytropidoceras (Benavidesites), with type species

Venezoliceras harrisoni Benavides-Caceres (1956: 460, pl. 53 (fig. 6)), for this

homoeomorphic development.

The origins of Adkinsites are obscure; Young (1966) would derive this

taxon from Dipoloceras, but this view is unacceptable to the writer. They could

represent derivatives of the more densely ribbed O. (Mirapelia) species or of

paucicostate Oxytropidoceras s.s., or of both. This taxon is not present in the

Angolan material and hence the writer defers judgement. Because of its

obscure, and perhaps polyphyletic origins, Young (1966) is followed in treating

Adkinsites as a genus, of which Androiavites Collignon (1936) is a synonym.

Fig. 20. Mojsisoviczia cf. ventanillensis (Gabb). A reconstruction based upon

BM-C78865, from the Middle Albian of Zululand. x 1.

296 ANNALS OF THE SOUTH AFRICAN MUSEUM

Mortoniceras (Pervinquieria) rigidum Spath (1933: 413, figs 142, 144f)

(Fig. 13E-F herein) is recorded from Bed VIII (=D. cristatum Zone) at

Folkestone and is, as such, the earliest described species of Mortoniceras. It

differs from the latter genus, however, in having rather fine, distant ribs with a

steep adoral surface and a sloping adapical surface, lacking any sign of a

mid-lateral tubercle, and in lacking the doubling of the ventrolateral tubercle so

typical of Mortoniceras. Indeed, the characters of ornament ally M. rigidum

with the Mojsisovicziinae and it seems likely that M. rigidum is closely allied to,

and perhaps descended from Adkinsites. Since the origins of Mortoniceras are

generally thought to lie in Dipoloceras (Wright in Arkell et al. 1957), the

similarities are due to convergence. It is proposed, therefore, to make M. rigi-

dum Spath the type species for the new genus Mortoniceratoides. It differs from

Adkinsites in having a subquadrate whorl section, low ventral keel, and with a

symmetrically bifid first lateral saddle.

As discussed by Kennedy & Cooper (1977), Mojsisoviczia and Falloticeras

are closely allied and, on the basis of the available evidence, Falloticeras may

reasonably be considered a neotonous offshoot of Mojsisoviczia. From their

first appearance (Fig. 20), the ribs of Mojsisoviczia are coarse and simple and

the origins of this taxon seem to lie in O. (Mirapelia) sergipense (White) or a

closely allied form.

Dipoloceras is believed by Spath (1931) to have descended from Oxytropi-

doceras, and is included in the Mojsisovicziinae by Wright (in Arkell et al.

1957). However, the inflated whorls, low ventral keel and strong spiral

ornament suggest a closer relationship with the Mortoniceratinae, to which

subfamily Dipoloceras is here referred. The suggested phylogeny within the

Mojsisovicziinae, as here interpreted, is shown as Figure 21.

Oxytropidoceras (Mirapelia) buarquianum (White, 1887)

Figs 3A-B, 6B, 10A-B, 15A-B, 19C-E, 22D-E, 23A-D, F-G, 24-25, 27

Ammonites buarquianus White, 1887: 222, pl. 24 (figs 3-4 only), pl. 25 (figs 7-8).

Schloenbachia cf. roissyana (d’Orbigny) Douvillé, 1906: 147, pl. 4 (fig. 3).

Schloenbachia aff. belknapi (Marcou) Douvillé, 1906: 148, pl. 2 (fig. 4).

Schloenbachia cf. belknapi Bose (non Marcou) Douglas, 1921: 269, pl. 17 (figs 1-2).

Schloenbachia cf. chihuahuaensis Bése, Douglas, 1921: 269, pl. 17 (fig. 3).

Oxytropidoceras buarquianum (White) Maury, 1936, pl. 19 (figs 2-3), pl. 25 (figs 5-6). Oliveira

& Leonardos, 1943, pl. 27 (fig. 7). Young, 1966: 89, pl. 38 (figs 1-3). Beurlen, 1970: 464,

pl. 5 (figs 1-2), fig. 18.

? Oxytropidoceras colcanapi Collignon, 1936: 182, pl. 18 (fig. 7), fig. 12k.

? Oxytropidoceras sp.juv., Spath, 1930: 61, pl. 9 (fig. 18).

Oxytropidoceras packardi Anderson, 1938: 198, pl. 50 (fig. 1).

Oxytropidoceras douglasi Knetchel, 1947: 106, pl. 24 (figs 1-4), pl. 25 (figs 1-2), pl. 26, pl. 27

(figs 2-3), pl. 28 (fig. 1). Young, 1966: 88, pl. 10 (figs 1, 5), pl. 36 (figs 3-4), pl. 37

(figs 4-5).

? Oxytropidoceras involutum Beurlen, 1952: 162, fig. 3.

? Oxytropidoceras (Manuaniceras) involutum Beurlen, 1970: 465, pl. 5 (fig. 4).

Oxytropidoceras sp. A, Beurlen, 1970: 464, pl. 5 (fig. 3).

LOWER CRETACEOUS AMMONITES FROM ANGOLA 297

Laraiceras

Venezoliceras

O. (Mirapelia)

Mortoniceratoides

Adkinsites

O. (Oxytropidoceras)

O. (Benavidesites)

Falloticeras

Mojsisoviczia

Fig. 21. A suggested phylogeny of the Mojsisovicziinae.

Material

Forty-five specimens, including SAM-—PCA2617-2618, 2621-2622,

2627-2630, 2632, 2637, 2640-2645, 2648, 2651, 2654, 2659, 2663, 2665-2667,

2669, 2673-2674, 2676, 2678, 2693, 3603-3604, 3755, 3762 and 3765, all pre-

served as limestone steinkerns.

Description

The Angolan population is polytypic, with morphotypes agreeing exactly

with O. buarquianum (White), O. packardi Anderson, O. douglasi Knetchel,

O. salasi Young, and two specimens very closely approaching O. mirapelianum

(d’Orbigny). The relationship between these morphotypes is shown in Figure

26. Because of this wide range of intraspecific variation, no single description

will fully cover all morphotypes and hence they are described separately.

Two specimens, SAM—PCA2656-2657, very closely approach O. mirapelia-

num (d’Orbigny) and, with a typological approach, would be referred to that

species. The Angolan examples (Fig. 10A—B) are, however, insensibly con-

298 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 22. A. Douvilleiceras variabile Tavani, D’Orbigny’s (1841, pl. 72 (fig. 5)) protograph,

x 0,5. B-C. Mojsisoviczia delaruei (d’Orbigny), NHMP-5761, one of D’Orbigny’s syntypes

from Clar, France. D-E. Oxytropidoceras (Mirapelia) buarquianum (White), SAM-—PCA2641,

a rather densely ribbed douglasi morphotype, thus transitional to salasi variants. All x 1 unless

otherwise stated.

LOWER CRETACEOUS AMMONITES FROM ANGOLA 299

Fig. 23. A-D, F-G. Whorl sections of Oxytropidoceras (Mirapelia) buarquianum (White).

A. SAM-PCA2656, a douglasi morphotype. B. SAM-PCA2644, a douglasi morphotype.

C. SAM-PCA3603, a salasi morphotype. D. SAM-PCA2693, a typical buarquianum morpho-

type. F. SAM-PCA2622, a douglasi morphotype. G. SAM-PCA2641, a douglasi morpho-

type. E, H. Whorl sections of O. (M.) sergipense (White). E. SAM-PCA5444. H. A

unnumbered specimen in the South African Museum. All x 1.

300 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 24. Oxytropidoceras (Mirapelia) buarquianum (White), SAM-—PCA3418, a douglasi mor-

photype, X 1.

LOWER CRETACEOUS AMMONITES FROM ANGOLA 301

Fig. 25. Oxytropidoceras (Mirapelia) buarquianum (White). A-B. SAM-PCA2693, the typical

variant. C. SAM-PCA2674, a douglasi morphotype. D. SAM—PCA2665, a rather eroded,

finely ribbed variant. All x 1.

302 ANNALS OF THE SOUTH AFRICAN MUSEUM

salasi buarquianum

3 (7%) 3 (7%)

2 (4%) 6 (13%)

douglasi

29 (64%)

2 (4%)

sergipense mirapelianum

Fig. 26. Interrelationships between the Oxytropidoceras (Mirapelia)

buarquianum morphotypes and closely allied species. Figures given

are the number of morphotypes in the present collection followed,

in parentheses, by the percentage which they constitute.

nected to O. douglasi morphotypes and differ from D’Orbigny’s (1841) species

(Fig. 14D-E) in being slightly less inflated and in having the ribs somewhat

thicker at the umbilical margin.

The O. douglasi morphotypes are the most abundant in the present

collection and show the following features: shell compressed, evolute (umbili-

cus 24-28 % of the diameter), with a compressed, lanceolate whorl section and

a prominent, sharp, high, siphonal keel. The umbilicus is rather wide and

shallow, with fairly steep umbilical walls and evenly rounded shoulders at

moderate diameters. The umbilical walls become increasingly inclined with

growth and, in maturity, the umbilical shoulder is gently rounded and indis-

tinct. At this stage, the outer whorl covers about 15 per cent of the ribbing of

the preceding whorl. Maximum width is slightly below mid-flank in most

individuals. Ornament comprises simple, generally flexuous ribs, which arise at

the umbilical seam but only become prominent on the flanks. All ribs are

slightly prorsiradiate, steepest adorally and convex adapically, and broaden

towards the ventrolateral shoulders where they swell but do not form tubercles.

LOWER CRETACEOUS AMMONITES FROM ANGOLA 303

Fig. 27. Oxytropidoceras (Mirapelia) buarquianum (White). The

suture line, somewhat simplified by erosion, of SAM-PCA2693, a

douglasi morphotype. Approx. X 2.

There are 13—20 ribs per half whorl. A somewhat eroded suture-line is shown as

Figure 27.

O. buarquianum morphotypes are insensibly connected to O. douglasi

morphotypes (Fig. 3A—B). Typically (Fig. 25A-B), this morphotype is strongly

compressed, with 22-32 broad, low, weak ribs per whorl, and an indistinct

umbilical wall. It is perhaps worth noting that it is a ‘law’ of polytypic

ammonite species that the compressed variants are weakly ornamented, and

that strength of ornament increases with inflation.

Two examples, SAM-—PCA 3603-3604, show the rather dense, straight ribs

of O. salasi Young, becoming projected near the venter (Fig. 19D-E), and are

connected by intermediates to O. douglasi. These O. salasi variants show a low

umbilical wall, broad convex flanks and a lanceolate whorl section, and were

clearly rather evolute. Although the siphonal keel is not preserved, it certainly

stood well above the venter. The dense, narrow, simple ribs are distinctly

prorsiradiate and only very slightly flexuous, with at least twenty-two ribs per

half whorl. The ribs swell slightly at the ventrolateral shoulders and curve

strongly forward to meet the siphonal keel.

Discussion

The Angolan material shows an insensible transition between O. buarquia-

num (White) and O. douglasi Knetchel and they are synonyms. It is unfortun-

ate that White’s (1887) species has priority because the O. douglasi morpho-

types predominate. There is little to separate O. packardi Anderson from the

O. douglasi morphotypes and it should also fall into synonymy. Several of the

Angolan morphotypes are extremely close to O. mirapelianum, which is a

broadly contemporaneous European species. However, until the population

304 ANNALS OF THE SOUTH AFRICAN MUSEUM

structure of D’Orbigny’s (1841) species is better understood, they are main-

tained as specifically distinct.

As already noted, there are O. salasi morphotypes within the Aswalen

material, which are connected by transitions to O. douglasi morphotypes, but

they constitute only 4 per cent of the present material. Because of this, and

because Young (1966) had over 300 specimens of O. salasi from the Key Valley

Marl, the Texas form is maintained as a distinct species. Occasional O. salasi

morphotypes within the Angolan population merely indicate that O. salasi is

descended from an O. buarquianum ancestor by a major change in population

structure. Oxytropidoceras stenzeli Young (1966: 93, pl. 22 (fig. 1), pl. 26

(fig. 1), pl. 34 (fig. 1), pl. 35 (fig. 4), figs 7h, 18c) is a Middle to low Upper

Albian species that may not bear separation from O. salasi.

Collignon (1936) recorded O. mirapelianum, O. colcanapi Collignon, O.

boulei Collignon, and O. bravoense Collignon (non Bose) from the same level

and locality (Berambo) in the Middle Albian of Madagascar. His O. colcanapi

is certainly very close to O. buarquianum, although the true affinities of the

Madagascan material must await reassessment at the population level.

The species of Oxytropidoceras figured by Reyment (1955) from Nigeria

are all poorly preserved juveniles with the simple, flexuous ribbing of O.

(Mirapelia). Additional and better preserved material is required for a satisfac-

tory identification.

Oxytropidoceras chihuahuaense (Bose) (1910: 73, pl. 5 (figs 3-4), pl. 7

(figs 3-4), pl. 8 (figs 1-2)) was assigned by Young (1966) to Venezoliceras, but

the absence of a flank tubercle clearly places it in O. (Mirapelia). The lectotype

is the original of the specimen figured by Bose (1910, pl. 7 (figs 3-4), pl. 8

(fig. 1)), which shows rather rigid, slightly prorsiradiate single ribs that broaden

ventrally and terminate in weak ventrolateral swellings. These features are

within the range of variation of the Angolan material, but since BOése’s species

is, in Texas at least (Young 1966), dated as upper Middle Albian—lower Upper

Albian, it is maintained as distinct.

Oxytropidoceras involutum Beurlen is based upon immature material that

is very close to typical examples of this species. It is likely to prove a synonym

of O. buarquianum.

Oxytropidoceras (Mirapelia) sergipense (White, 1887)

Figs 11B, 18A-B, 23E, H, 28

Ammonites sergipensis White, 1887: 221, pl. 24 (figs 1-2).

Pervinquieria sergipensis (White) ee 1930: 294; 1936: 236, pl. 24 (figs 3-4).

? Oxytropidoceras buarquianum (White) Maury, 1936: 250, pl. 9 (fig. 1 only).

Oxytropidoceras mauryae Beurlen, 1952: 162, fig. 3.

Dipoloceras sergipense (White) Young, 1966: 20, 22, 24.

Oxytropidoceras (Venezoliceras) sergipense (White) Renz, 1968: 630.

Oxytropidoceras (Androiavites) mauryae Beurlen, 1970: 468, pl. 6 (fig. 1).

Non Mortoniceras sergipensis (White) Beurlen, 1970: 468, pl. 6 (figs 2-4), fig. 19.

LOWER CRETACEOUS AMMONITES FROM ANGOLA 305

Fig. 28. Oxytropidoceras (Mirapelia) sergipense (White). A-B. White’s (1887) origi-

nal illustration. C—D. The original of White’s illustration, herein selected as lecto-

type, in the Natural History Museum, Rio de Janeiro. Photo: P. Bengtson.

Both x 1.

306 ANNALS OF THE SOUTH AFRICAN MUSEUM

Material

Six specimens in the South African Museum, SAM-—PCA3755, 3765, and

5444, together with three unnumbered examples. All are preserved as lime-

stone steinkerns.

Description

The shell is rather inflated and moderately evolute, with the outer whorl

covering about 25 per cent of the preceding whorl. The umbilicus is moderately

wide (32-35% of the diameter) and fairly shallow, with steep umbilical walls

and evenly rounded shoulders. Intercostally the whorl section is oval, com-

pressed, whereas costally it is subquadrate (Fig. 23E, H). Ribs begin at the

umbilical seam and, across the flank, are slightly flexuous and prorsiradiate,

terminating in prominent ventrolateral tubercles that are projected forward on

the venter. There are thirty ribs on the outer whorl. The flanks are convex and

converge slightly towards the venter, with maximum width about one-third of

the way up the flanks. The keel is not preserved but must have stood high

above the venter.

Discussion

The confusion surrounding the generic status of White’s (1887) species is

evident from the synonymy. It is, indeed, very close to Venezoliceras, as noted

by Renz (1968), but lacks the development of flank tubercles. On the other

hand, it is also very similar to the more inflated Oxytropidoceras douglasi

morphotypes with which it coexists, differing only in the very pronounced

development of ventrolateral tubercles. In gross morphology and stratigraphic

position, therefore, O. (M.) sergipense is intermediate between O. (Mirapelia)

and Venezoliceras. Phylogenetically, it is perhaps worth noting that Young

(1966) assigned this species to Dipoloceras, while Spath (1932) referred such

typical O. (Mirapelia) species as O. evansi (Spath), and even O. mirapelianum

(d’Orbigny) itself, to Dipoloceras. As such, it seems likely that the origins of

Dipoloceras also lie in O. (Mirapelia) of the sergipense group.

Oxytropidoceras (Androiavites) mauryae Beurlen shows the same promi-

nent ventrolateral tubercles and simple ribbing as O. (M.) sergipense and is

here regarded as conspecific. The specimen figured by Beurlen (1970) is an

Upper Albian Mortoniceras (Angolaites) with distinct umbilical and doubled

ventrolateral tubercles.

Oxytropidoceras (Mirapelia) sergipense (White) is very close to certain

species of Mojsisoviczia (Figs 20, 22B—C), from which it is readily distinguished

by its greater compression and the absence of a lateral tubercle. In this respect

the figured but undescribed material of Mojsisoviczia aff. delaruei (d’Orbigny)

(Spath 1930: 61, pl. 9 (figs 13, 16)) closely resembles the present species, since

a lateral tubercle is not evident in the illustrations. It seems reasonable to

assume that the ancestry of Mojsisoviczia lies in O. (Mirapelia) of the

sergipense group.

pidoceras) boesei Knechtel, SAM—PCAS5452, x 1.

fe)

)

jaa

fe)

LOWER CRET

29. Oxytropidoceras (Oxytro

Fig.

308 ANNALS OF THE SOUTH AFRICAN MUSEUM

Oxytropidoceras (Oxytropidoceras) boesei Knechtel, 1947

Figs 29-31A

Oxytropidoceras (Manuaniceras) bosei Knechtel, 1947: 109, pl. 27 (fig. 1).

? Manuaniceras uddeni Young, 1966: 95, pl. 12 (figs 1, 4-5), pl. 13 (fig. 1), pl. 16 (figs 1, 3),

figs 10b, 12b.

Material

Three specimens, SAM—PCA5452-5453 and an unnumbered example in

the South African Museum, preserved as limestone steinkerns.

Description

The Angolan material comprises several rather eroded internal moulds of

body chamber fragments that, because of scaphitoid-uncoiling of the body

chamber, appear to be more evolute (umbilicus 33% of the diameter) than the

earlier growth stages actually were. The shell is strongly compressed, with a

lanceolate whorl section (Fig. 30) and broad, convex flanks. Maximum width is

about one-third of the way up the flanks. Although the siphonal keel is not

preserved, it certainly stood well above the venter.

Ornament comprises dense, flexuous flank ribs that arise at, or close to,

the umbilical seam and pass forward across the flanks. The ribs are narrower

than the interspaces with a steep, concave, adoral surface and a sloping,

convex, adapical face. They frequently bifurcate close to the umbilical seam,

but only rarely at, or above, mid-flank. There are 8-9 ribs along the venter in a

distance equal to the whorl height. There is no sign of bullae on any part of the

flanks.

Fig. 30. Oxytropidoceras (Oxytropidoceras) boesei Knechtel. Whorl

sections. A. SAM-PCAS5452. B. SAM-PCAS5453. x 1.

LOWER CRETACEOUS AMMONITES FROM ANGOLA 309

Discussion

Oxytropidoceras (Manuaniceras) boesei Knetchel was based upon frag-

mentary material, without proper description, which shows no features to

distinguish it from the Angolan material. The Texas species, Manuaniceras

uddeni Young, which coexists with O. (M.) buarquianum, is very close to the

present material. It is said to differ in the presence of a few very weak bullae at

the umbilical shoulder, and sometimes also at the point of bifurcation or

intercalation of a rib. Since the presence of such bullae is likely to be markedly

affected by state of preservation, M. uddeni is probably a synonym of

O. boesei.

Oxytropidoceras roissyanum (d’Orbigny) (Fig. 5A-B) is difficult to com-

pare with the present species because the known material of both species

represents vastly different growth stages. So far as can be judged, O. roissya-

num is much more inflated, with stronger, more robust ribs, about as wide as

the interspaces, and does not show bifurcation above the umbilical shoulder.

Oxytropidoceras applanatus Collignon (1936: 183, pl. 16, (fig. 5)) is doubtfully

distinct from O. roissyanum.

Oxytropidoceras manuanense (Spath) (1921: 281, pl. 25 (fig. 1)) (Fig. 31B)

resembles the present species in lacking flattened ribs, but differs in that nearly

all ribs bifurcate at some level on the flanks and in the effacement of ribbing in

maturity.

Oxytropidoceras cantianum Spath (Fig. 14F—G) is an Upper Albian (Dipo-

loceras cristatum Zone) species that is based upon a juvenile showing strongly

branching ribs. It closely approaches the example figured by Young (1966, pl. 7

(figs 4, 6)) as ‘probably M. carbonarium (Gabb)’, and Owen (1971) seems to be

right in regarding it a synonym of O. carbonarium.

Oxytropidoceras aroeirium Maury (1936: 251, pl. 26, (fig. 7)) is, to judge

from the description, very close to the present species. Unfortunately, the

writer has not seen the illustrations of this species and thus further comment is

unjustified.

AGE OF THE PRESENT FAUNA

Douvilleiceras mammillatum (Schlotheim) has long been considered diag-

nostic of the uppermost biostratigraphic zone in the Lower Albian, to which it

gives its name. Thus, the rich Douvilleiceras faunas from the rest of the world

are almost invariably assigned to the zone of D. mammillatum and considered

to be of late early Albian age. Despite the fact that Douvilleiceras has long

been known to persist into the Middle Albian (Casey 1962; Owen 1971;

Destombes et al. 1977), including D. mammillatum itself (Fig. 12E-F), this has

never been a problem in the boreal realm where the incoming of Hoplites forms

an easily recognizable and diagnostic base to the Middle Albian. Outside the

hoplitinid faunal province, however, no such aid is available and the problem of

310 ANNALS OF THE SOUTH AFRICAN MUSEUM

SAM-PCAS5453.__B. Oxytropidoceras (Oxytropidoceras) man-

uanense (Spath), SAM-—2726, a paratype.

LOWER CRETACEOUS AMMONITES FROM ANGOLA Sila

the Lower—Middle Albian boundary is far more complex. These problems led

Young (1966) to suggest that Lyelliceras may date a younger level in South

America than it does in Europe. Contrary to Young’s (1966) opinion, however,

the writer feels that Lyelliceras is critical to the problem of the Lower—Middle

Albian boundary, in view of its widespread geographic distribution and com-

mon association with hoplitinids in the boreal realm.

In the Anglo-Paris basin, the type region for the Albian Stage, Owen

(1971) recognized the following subdivisions of the Middle Albian:

Anahoplites daviesi Subzone

Euhoplites lautus Z

BOP eS, AUS ONE | Euhoplites nitidus Subzone

Euhoplites meandrinus Subzone

Mojsisoviczia subdelaruei Subzone

Dimorphoplites niobe Subzone

Euhoplites loricatus Zone

| Anahoplites intermedius Subzone

Hoplites spathi Subzone

Hoplites dentatus Zone Lyelliceras lyelli Subzone

Isohoplites eodentatus Subzone

In the Anglo-Paris basin, Douvilleiceras inaequinodum (Quenstedt) does

not range above the eodentatus Subzone, while Oxytropidoceras (Mirapelia)

mirapelianum (d’Orbigny). is a constituent of the Hoplites spathi Subzone

(Owen 1971). Moreover in Peru, Benavides-Caceres (1956) records Oxytropi-

doceras ‘douglas in association with Lyelliceras lyelli (d’Orbigny). There can

also be little doubt that the Angolan Oxytropidoceras fauna is strictly contem-

poraneous with those from the Texan zone of O. salasi, and it is certainly also

represented in Brazil (White 1887; Maury 1936; Beurlen 1970). As such, the

Lyelliceras lyelli Subzone is represented in the south-central Atlantic region by

Oxytropidoceras buarquianum (White) and/or Lyelliceras lyelli (d’Orbigny),

and their associated species. The underlying beds in Angola, dominated by

Douvilleiceras mammillatum aequinodum (Quenstedt) and D. inaequinodum

(Quenstedt), are thus certainly to be correlated with the /sohoplites eodentatus

Subzone of the Anglo-Paris basin. It is perhaps worthy of note that O. mirape-

lianum (d’Orbigny) is a replacement name for Ammonites cristatus Quenstedt

(non DeLuc) and, as such, Quenstedt (1849) was dealing with a faunal horizon

closely comparable, and probably strictly contemporaneous, with those at

Dombe Grande.

As such, the Dombe Grande faunas are here regarded as of basal Middle

Albian age, to be correlated with the Isohoplites eodentatus and Lyelliceras

lyelli Subzones of the European succession. The absence of lyelliceratids and

brancoceratids is enigmatic. Since Oxytropidoceras species are relatively long-

lived, the Oxytropidoceras (M.) buarquianum faunule may prove to range

somewhat higher. The fact that many of the Douvilleiceras assemblages from

around the world could now prove to be of basal Middle Albian age suggests

312 ANNALS OF THE SOUTH AFRICAN MUSEUM

that the late early Albian eustatic transgression (Cooper 1977) might actually

have peaked during the earliest Middle Albian.

SUMMARY

Two Middle Albian faunules rich in numbers, but poor in species, are

described from the vicinity of Dombe Grande, Angola. The lower faunule,

which is correlated with the I[sohoplites eodentatus Subzone of the European

sequence has yielded Douvilleiceras mammillatum aequinodum (Quenstedt),

D. inaequinodum (Quenstedt), D. variabile Tavani and Puzosia_bistricta

(White). The upper faunule has yielded Oxytropidoceras (Oxytropidoceras)

boesei Knechtel, O. (M.) buarquianum (White), O. (M.) sergipense (White),

Puzosia bistricta (White), Protanisoceras sp. and a Hamites sp., and is to be

correlated with the Lyelliceras lyelli Subzone of the Anglo-Paris basin. Mojsiso-

vicziinid phylogeny is discussed, and the following new taxa introduced: Morto-

niceratoides gen. nov., Oxytropidoceras (Mirapelia) subgen. nov. and O. (Bena-

videsites) subgen. nov., while Manuaniceras is included in the synonymy of

Oxytropidoceras S.s.

ACKNOWLEDGEMENTS

I am grateful to Dr W. J. Kennedy for providing me with photographs of

D’Orbigny’s type material, and to Dr P. Bengtson for photographs of the

Brazilian material. I should also like to express my thanks to Dr R. Kirby for

allowing me to study his collections from the Middle Albian of France. This

paper was much improved by the valuable criticism of Prof. K. Young and Dr

P. Destombes.

REFERENCES

ANDERSON, F. M. 1938. Lower Cretaceous deposits in California and Oregon. Spec. Pap. geol.

Soc. Am. 16: 1-339.

ARKELL, W. J., KuMMEL, B. & Wricut, C. W. 1957. Mesozoic Ammonoidea. Systematic

description. In: Moore, R. C., ed. Treatise on invertebrate paleontology. Part L. Mollusca

4. Cephalopoda. Ammonoidea: L129-L437. Boulder: Geological Society of America;

Lawrence: University of Kansas Press.

BENAVIDES-CACERES, V. E. 1956. Cretaceous System in northern Peru. Bull. Am. Mus. nat.

Hist. 108: 359-493.

BEuRLEN, K. 1952. A linha de sutura de Oxytropidoceras. Contribugao ao conhecimento da

familia Dipoloceratidae. Anais Acad. bras. Ciénc. 24: 159-169.

BeurRLEN, G. 1970. A fauna do complexo riachuelo/marium. I. Ammonoidea. Boln téc.

Petrobras, Rio de J. 11: 437-482.

Bose, E. 1910. Monografia geoldgica y paleontolégia del Cerro de Muleros circa de cuidad

Juarez, estado de Chihuahua y description de la fauna Cretacea de la Encantada, placer de

Guadalupe, estado de Chihuahua, Mexico. Bol. Inst. geol. Méx. 25: 1-193.

BREISTROFFER, M. 1947. Sur les zones d’ammonites dans |’Albien de France et d’Angleterre.

Trav. Lab. géol. Univ. Grenoble 26: 1-88.

Casey, R. 1962. A monograph of the Ammonoidea of the Lower Greensand. Part 4. Palaeont.

Soc. Monogr.: 217-288.

LOWER CRETACEOUS AMMONITES FROM ANGOLA 313)

CHOFFAT, P. & LorioL, P. DE 1888. Matériaux pour |’étude stratigraphique et paléontologique

de la province d’Angola. Mém. Soc. Phys. Genéve 30: 1-116.

CoLuiGNon, M. 1936. Les Oxytropidoceras de ! Albien moyen (niveau supérieur) de la province

d’Analalava. /n: Besairte, H. Recherches géologiques 4 Madagascar. Premiére suite. La

géologie du nord-ouest. Mém. Acad. Malgache 21: 176-187.

CoLuiGNon, M. 1950. Recherches sur les faunes albiennes de Madagascar. 3. L’Albien de

Komihevitra. Annis géol. Serv. Mines Madagascar 17: 21-54.

CoLLiGNon, M. 1963. Atlas des fossiles caracteristiques de Madagascar (Ammonites). IX.

Albien. Tananarive: Service géologique.

CoLuicNon, M. 1966. Les céphalopodes crétacés du bassin cétier de Tarfaya. Notes Mém. Serv.

Mines Carte géol. Maroc 175: 1-148.

Cooper, M. R. 1976. The mid-Cretaceous (Albian-Turonian) biostratigraphy of Angola. Annls

Mus. Hist. nat. Nice 4: 16.1-16.22.

Cooper, M. R. 1977. Eustacy during the Cretaceous: its implications and importance.

Palaeogeogr., Palaeoclimat., Palaeoecol. 22: 1-60.

DeEsTOMBES, P., GAMBLE, H. J., JuicNet, P. & Owen, H. G. 1977. Cretaceous and Lower

Tertiary of Seine-Maritime, France: a guide to key localities. Proc. Geol. Assoc. 88: 15-38.

Douctas, J. A. 1921. Geological sections through the Andes of Peru and Bolivia. III. From the

port of Callao to the river Perene. Q. JI geol. Soc. Lond. 77: 246-284.

DovuviLLE, R. 1906. Sur les ammonites du crétacé Sud-Américain. Annis Soc. r. zool. malacol.

Belg. 41: 142-155.

HowartH, M. K. 1965. Cretaceous ammonites and nautiloids from Angola. Bull. Br. Mus. nat.

Hist. (Geol.) 10: 335-412.

Hyatt, A. 1903. Pseudoceratites of the Cretaceous. Monogr. U.S. geol. Surv. 44: 1-351.

KENNEDY, W. J. & CopBan. W. A. 1976. Aspects of ammonite biology, biogeography, and

biostratigraphy. Spec. Pap. Palaeont. 17: 1-94.

KENNEDY, W. J. & Cooper, M. R. 1977. The micromorph Albian ammonite Falloticeras

Parona and Bonarelli. Palaeontology 20: 793-804.

KNECHTEL, M. M. 1947. Cephalopoda. Part I. In: KNEcHTEL, M. M., RicHarps, E. F. &

RaATHBUN, M. V. Mesozoic fossils of the Peruvian Andes. Johns Hopkins Univ. Stud. Geol.

15: 81-128.

Maury, C. J. 1930. O Cretaceo da Parahyba do Norte. Monogr. Serv. geol. min. Brazil

8: 1-308.

Maury, C. J. 1936. O Crétaceo de Sergipe. Monogr. Serv. geol. min. Brazil 11: 1-283.

McLearn, F. H. 1972. Ammonoids of the Lower Cretaceous sandstone member of the Haida

Formation, Skidegate Inlet, Queen Charlotte Islands, western British Columbia. Bull.

geol. Surv. Canada 188: 1-78.

Mirzoyev, G. G. 1967. New species of Douvilleiceras from Lower Albian deposits on the

southwestern spurs of the Gissar Range. Paleont. J. 1: 53-63.

Neto, M. G. M. 1960. Géologie de la région Benguela-Cuio. Bolm Serv. geol. min. Angola

1: 89-99.

Neto, M. G. M. 1961. As bacias sedimentares de Benguela e Mocamedes. Bolm Serv. geol.

min. Angola 3: 63-93.

O.iverrA, A. I. & LEonNARDOS, O. H. 1943. Geologia de Brasil. 2nd ed. Rio de Janeiro: Service

de Informacao Agricola.

Orpicny, A. D’. 1840-41. Paléontologie francaise. Terrains crétacés. 1. Céphalopodes. Paris:

Masson.

Owen, H. G. 1971. Middle Albian stratigraphy in the Anglo-Paris Basin. Bull. Br. Mus. nat.

Hist. (geol.) Suppl. 8: 1-164.

Parona, C. F. & BONARELLI, E. G. 1897. Fossili albiani d’Escragnolles, del Nizzardo e della

Liguria occidentale. Palaeontogr. ital. 2: 53-112.

Picret, F. J. & REeNeviER, E. 1854-9. Description des fossiles du terrain Aptien de la

Perte-du-Rhone et des environs de Ste Croix. Mat. pal. Suisse 1: 1-184.

QUENSTEDT, F. A. 1849. Petrofacten Deutschlands. 1. Cephalopoden. 6: 473-580. Tubingen.

RENz, O. 1968. Uber die Untergattungen Venezoliceras Spath und Laraiceras n.subgen. der

Gattung Oxytropidoceras Stieler (Ammonoidea) aus den Venezolanischen Anden. Eclogae

geol. Helv. 61: 615-655.

REYMENT, R. A. 1955. The Cretaceous Ammonoidea of southern Nigeria and the southern

Cameroons. Bull. geol. Surv. Nigeria 25: 1-112.

314 ANNALS OF THE SOUTH AFRICAN MUSEUM

Scotr, G. 1937. Ammonites of the genera Sonneratia and Douvilleiceras from the Cretaceous of

Colombia. J. Paleont. 11: 34-37.

Scotr, G. 1940. Cephalopods from the Cretaceous Trinity Group of the south-central United

States. Univ. Texas Publ. 3945: 969-1106.

SpatH, L. F. 1921. On the Cretaceous Cephalopoda from Zululand. Ann. S. Afr. Mus.

12: 217-321.

SpaTH, L. F. 1923-43. A monograph of the Ammonoidea of the Gault. Palaeont. Soc.

Monogr.: 1-787.

SpatH, L. F. 1930. The fauna of the Samana Range and some of the neighbouring areas. The

Lower Cretaceous Ammonoidea, with notes on the Albian Cephalopoda from Hazara.

Mem. geol. Surv. India palaeont. indica (n.s.) 15: 51-66.

TAVANI, G. 1942. Paleontologia della Somalia. III. Fossili del Cretaceo. 6. Molluschi del

Cretaceo della Somalia. Palaeontogr. ital. 32 (4): 7-47.

TavaNI, G. 1949. Fauna malacologica Cretacea della Somalia e dell’Ogaden. 2. Gastropoda—

Cephalopoda—conclusioni. Palaeontogr. ital. 45: 1-76.

Waite, C. A. 1887. Contribugdes a palaeontologia do Brazil. Archos Mus. nac., Rio de J.

7: 1-273.

YounG, K. 1966. Texas Mojsisovicziinae (Ammonoidea) and the zonation of the Fredricks-

burg. Mem. geol. Soc. Am. 100: 1-225.

Youn, K. 1974. Lower Albian and Aptian (Cretaceous) ammonites of Texas. Geosci. Man

8: 175-228.

6. SYSTEMATIC papers must conform to the Jnternational code of zoological nomenclature

(particularly Articles 22 and 51).

Names of new taxa, combinations, synonyms, etc., when used for the first time, must be

followed by the appropriate Latin (not English) abbreviation, e.g. gen. nov., sp. nov., comb.

Nnov., syn. nov., etc.

An author’s name when cited must follow the name of the taxon without intervening

punctuation and not be abbreviated; if the year is added, a comma must separate author’s

name and year. The author’s name (and date, if cited) must be placed in parentheses if a

species or subspecies is transferred from its original genus. The name of a subsequent user of

a scientific name must be separated from the scientific name by a colon.

Synonymy arrangement should be according to chronology of names, i.e. all published

scientific names by which the species previously has been designated are listed in chronological

order, with all references to that name following in chronological order, e.g.:

Family Nuculanidae

Nuculana (Lembulus) bicuspidata (Gould, 1845)

Figs 14-15A

Nucula (Leda) bicuspidata Gould, 1845: 37.

Leda plicifera A. Adams, 1856: 50.

Laeda bicuspidata Hanley, 1859: 118, pl. 228 (fig. 73). Sowerby, 1871: pl. 2 (fig. 8a—b).

Nucula largillierti Philippi, 1861: 87.

Leda bicuspidata: Nicklés, 1950: 163, fig. 301; 1955: 110. Barnard, 1964: 234, figs 8-9.

Note punctuation in the above example:

comma separates author’s name and year

“semicolon separates more than one reference by the same author

full stop separates references by different authors

figures of plates are enclosed in parentheses to distinguish them from text-figures

dash, not comma, separates consecutive numbers

Synonymy arrangement according to chronology of bibliographic references, whereby

the year is placed in front of each entry, and the synonym repeated in full for each entry, is

not acceptable.

In describing new species, one specimen must be designated as the holotype; other speci-

mens mentioned in the original description are to be designated paratypes; additional material

not regarded as paratypes should be listed separately. The complete data (registration number,

depository, description of specimen, locality, collector, date) of the holotype and paratypes

must be recorded, e.g.:

Holotype

SAM-—A13535 in the South African Museum, Cape Town. Adult female from mid- tide region, King’s Beach

Port Elizabeth (33°51’S 25°39’E), collected by A. Smith, 15 January 1973.

Note standard form of writing South African Museum registration numbers and date.

7. SPECIAL HOUSE RULES

Capital initial letters

(a) The Figures, Maps and Tables of the paper when referred to in the text

> ‘

e.g. *... the Figure depicting C. namacolus...’; ‘... in C. namacolus (Fig. 10) .

(b) The prefixes of prefixed surnames in all languages, when used in the text, if not preceded

by initials or full names

e.g. Du Toit but A.L.du Toit; Von Huene but F. von Huene

e.g. Therocephalia, but therocephalian

Punctuation should be loose, omitting all not strictly necessary

Reference to the author should be expressed in the third person

Roman numerals should be converted to arabic, except when forming part of the title of a

book or article, such as

“Revision of the Crustacea. Part VIII. The Amphipoda.’

Specific name must not stand alone, but be preceded by the generic name or its abbreviation

to initial capital letter, provided the same generic name is used consecutively.

Name of new genus or species is not to be included in the title: it should be included in the

abstract, counter to Recommendation 23 of the Code, to meet the requirements of

Biological Abstracts.