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

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FiscHer, P. H., DuvaL, M. & Rarry, A. 1933. Etudes sur les échanges respiratoires des littorines. Archives de zoologie

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Koun, A. J. 19602. Ecological notes on Conus (Mollusca: Gastropoda) in the Trincomalee region of Ceylon. Annals and

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Koun, A. J. 19605. Spawning behaviour, egg masses and larval development in Conus from the Indian Ocean. Bulletin of

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(continued inside back cover)

ANNALS OF THE SOUTH AFRICAN MUSEUM

ANNALE VAN DIE SUID-AFRIKAANSE MUSEUM

Volume 104 Band

February 1996 Februarie

Part 11 #£Deel

7 uh >

“ui NOVI pew

A DESCRIPTION OF THE SKELETON OF

A BAURIID THEROCEPHALIAN FROM THE

EARLY TRIASSIC OF SOUTH AFRICA

GILLIAN M. KING

Cape Town Kaapstad

The ANNALS OF THE SOUTH AFRICAN MUSEUM

are issued in parts at irregular intervals as material

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D4597

A DESCRIPTION OF THE SKELETON OF A BAURIID

THEROCEPHALIAN FROM THE EARLY TRIASSIC OF SOUTH AFRICA

GILLIAN M. KING

Department of Karoo Palaeontology, South African Museum, Cape Town

(With 10 figures)

[MS accepted 21 May 1994]

ABSTRACT

The postcranial skeleton of a baurioid therocephalian (NMQR 3189) from the Cyno-

gnathus Assemblage Zone of South Africa is described and compared to that of other thero-

cephalians. The specimen constitutes the best-preserved skeleton of one of the latest

therocephalians known. In the structure of the vertebral column and scapula, NMQR 3189 is

very similar to the earliest therocephalians but it differs in the more gracile humerus, the

absence of very small phalanges in the manus, and the large obturator foramen.

CONTENTS

PAGE

PLEO GCOS Ae oe et Ane ora ate a Oper NE Abert arenes EAN Snare Hie UP USN yar eM M RRM Rn ea 379

DESCIP OMY sea ea.0 sass ese ereioe oat oaloscaw domgoe deer mrciacraitiaietalay Wcecimnsniomiicuetel ale shlocial ma seyantane mates 380

ILON EPRI ea paendsa aaa honed Suan BEaicaeE GUase tule Sa ciat oat ia naomi tara mah aactars Sa aise manors Sct 380

PORTE GLC FEL 8 pce aanqooe TREES a GOS UBC SCCas Ba GEHGe He nee Pe et an EME EE GUL RA Siiaey SAG saat a 383

Rectoralvoirdleand: forelimb” «o...c.cc arse acnate ae seo ce seen teare Camas. Memeeeeee 384

Relies oIrdlerand Mind imDreccases ecccen sete cee se eo eee eee ner eee erence 387

(COTES ONT) ite 5 ae Ste te RRR SO SO IL BF Ri ORE He Re RM LANA Cae eM, oh eI Om 391

PRE KHOWIEO SEMEN US reer a setae cio ciiee race ce ee Na alencte ea ee eta eic ota ETT ae aia 392

1 EAS STV 10 AN A NR RE IIE eR Aes rea ONS OP 7 UR een cE SM 392

PRU DTCVIALIONS reese eae as oe oe aT Ae alte OPTI eerste oie TA A Oe dager Ce Rea 393

INTRODUCTION

The postcranial skeleton of the therocephalian mammal-like reptiles has

been described by various authors (Watson 1931; Broom 1937; Boonstra 1938,

1964; Schaeffer 1941; Attridge 1956; Cys 1967; Kemp 1978, 1986) but is still

poorly known because complete and well-preserved skeletons are rare. A

recently discovered specimen of a reasonably complete, associated but disarticu-

lated skeleton will help to fill this gap and contribute to our understanding of the

group.

In South Africa, the therocephalians have a relatively long stratigraphic

history. Known from the lowest of the Late Permian Beaufort Group biozones,

the Eodicynodon-Tapinocaninus Assemblage Zone (Rubidge 1990), the range of

therocephalians extends into the Cynognathus Assemblage Zone (Rubidge in

press).

Therocephalian postcranial material is currently known from several of the

Beaufort assemblage zones. Cynariognathus Cys, 1967, is an example of an

early therocephalian. It is from a locality in the Tapinocephalus zone (Kitching

1977), which may be equivalent to either the Tapinocephalus or Pristerognathus

* Present address: Faculty of Classics, University of Cambridge, England.

379

Ann. S. Afr. Mus. 104 (11), 1996: 379-393, 10 figs.

380 ANNALS OF THE SOUTH AFRICAN MUSEUM

Assemblage Zone (Rubidge in press). Van den Heever (1987) considered the

genus Cynariognathus to be invalid. However, he did not study the specimen

described by Cys and therefore did not synonymize it with any other genus. For

the purposes of this paper, the specimen will continue to be referred to as

Cynariognathus.

Boonstra (1964) described postcranial elements of several genera from

localities that probably include Tapinocephalus Assemblage Zone and Pristero-

gnathus Assemblage Zone rocks. Mirotenthes Attridge, 1956, is probably from

the Cistecephalus Assemblage Zone, also Late Permian. Ericiolacerta Watson,

1931, and the regisaurid described by Kemp (1986) are both from the earliest

Triassic Lystrosaurus Assemblage Zone.

The present specimen is from the Cynognathus Assemblage Zone. The only

therocephalian of this age to be described in any detail is Bauria cynops (Broom

1937; Boonstra 1938; Schaeffer 1941) but, apart from the hind foot, no post-

cranial skeleton was described. The anterior skeleton of Aelurognathus browni

(also from the Cynognathus Assemblage Zone) was described briefly by Broom

(1906). The present specimen, therefore, makes an important contribution to

our knowledge of the morphology of the late therocephalians.

This paper describes the postcranial skeleton of the newly discovered form

and compares it with the skeleton of earlier therocephalians.

DESCRIPTION

The specimen (National Museum, Bloemfontein, NMQR 3189) consists of a

small block of mostly disarticulated skeletal elements in a soft grey-green matrix

(Figs 1, 2). Although most postcranial elements are present, the only cranial

material comprises the left ramus of the dentary and several isolated teeth.

The specimen comes from Cynognathus Assemblage Zone deposits on the

farm Eerstegeluk 131 near Bethlehem, Free State Province, South Africa.

The most recent classification of the Therocephalia is that of Hopson &

Barghusen (1986). Within their superfamily Baurioidea, the family Bauriidae is

defined by several characters, only one of which can be partially verified in the

present specimen: postcanine teeth greatly expanded transversely with crown-to-

crown occlusion. Within the Therocephalia, this is a character unique to the

Bauriidae and, in view of this, it is considered reasonable to identify the

NMQR 3189 specimen as a member of that family. In fact, as shown below, the

teeth are very similar to those of Bauria itself. The present specimen is

provisionally identified as Bauria cynops, the only therocephalian known from

the Cynognathus Assemblage Zone.

LOWER JAW

Only the left ramus of the dentary is preserved and of this the anterior tip

and its dentition are missing (Fig. 3). One complete tooth and the base of

another are present at the preserved anterior end of the jaw. These are simple,

pointed teeth followed by a short diastema. Next are four cheek teeth set in a

deep trough in the dorsal surface of the jaw. The first three teeth increase in size

posteriorly. The fourth tooth is damaged but appears to be smaller than the

third. There appear to be no sockets for further teeth.

A DESCRIPTION OF THE SKELETON OF A BAURIID THEROCEPHALIAN 381

Fig. 1. The partly prepared block of matrix containing NMQR 3189 showing the lateral

view of the dentary. Scale bar for photograph = 50 mm.

382 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 2. The partly prepared block of matrix containing NMQR 3189 showing the long

bones. Scale bar for photograph = 50 mm.

A DESCRIPTION OF THE SKELETON OF A BAURIID THEROCEPHALIAN 383

Fig. 3. The dentary of NMQR 3189 in lateral view. Missing bone is indicated by broken

lines. Hatching indicates a covering of matrix or overlying bone. Scale bar = 10 mm.

The posterior teeth are expanded mediolaterally. Those with crowns

preserved show one large lateral cusp and a ring of smaller cusps on the medial

edge (Fig. 4), as described by Gow (1978) and Kemp (1982) for Bauria.

The lateral surface of the dentary is without feature apart from an elongated

shallow depression that runs from just behind the symphysis to the base of the

well-developed coronoid process.

What remains of the symphysis has a smooth, shallowly concave (medio-

laterally) dorsal surface.

Fig. 4. The tooth crown (third most posterior tooth) of NMQR 3189.

A. Dorsal view. B. Lateral view. C. Medial view.

AXIAL SKELETON

Approximately 20 vertebrae are present in the block. None is closely articu-

lated to its neighbours, and neural arches and centra are frequently dis-

associated. Neural spines are low. The vertebrae are very similar to those

described by Kemp (1986) in a regisaurid baurioid.

384 ANNALS OF THE SOUTH AFRICAN MUSEUM

Approximately 15 ribs are preserved, the majority of which appear to be

complete. The seven vertebrae that lie anterior to the sacrum (or thereabouts)

are approximately in line and their ribs are almost in articulation. The transition

from long, slender ribs to shorter, broader more horizontal ones can be seen

clearly within this sequence. Attridge (1956) and Kemp (1986) also noted this

transition in the specimens they described and considered that it might indicate

the development of a transverse diaphragm. Kemp also thought it might be cor-

related with mammal-like features of the hind limb and its musculature. The

transition can be seen clearly even in the early Karoo form, Cynariognathus

(Cys 1967).

PECTORAL GIRDLE AND FORELIMB

Scapulae, clavicles, humeri, radii, ulnae and part of a manus are preserved.

The scapula (Fig. 5) is a delicate bone. The blade is narrow, flaring out

somewhat dorsally. A marked depression runs down the lateral surface

(Fig. 5—dep). Dorsally this begins near the anterior edge, but approaches the

posterior edge more ventrally. The depression is bounded on its posterior side

by a distinct ridge (Fig. 5—ri) that divides the scapular blade into two areas: a

flat posterodorsal surface (Fig. 5—fs) and the anteroventral depression just

described. The glenoid articulation is suboval. As in all known therocephalians,

an acromion process is absent. A small scar for the triceps origin is present dor-

sal to the glenoid on the posterior edge of the bone.

Fig. 5. The left scapula of NMQR 3189. A. Lateral view.

B. Anterior view. Hatching indicates matrix and the broken line

shows a restored outline. Scale bar = 10 mm.

A DESCRIPTION OF THE SKELETON OF A BAURIID THEROCEPHALIAN 385

The scapula of NMQR 3189 closely resembles that of Ericiolacerta

described by Watson (1931) and, although similar in general appearance to the

regisaurid described by Kemp (1986), that specimen seems to lack the promi-

nent ridge running across the scapular blade. The scapula of Mirotenthes

described by Attridge (1956) is much narrower than that of NMQR 3189, but

also shows the scapular ridge. The earliest of the described Karoo thero-

cephalians, Cynariognathus (Cys 1967), is a much larger animal than those

discussed so far and its scapula is correspondingly broader and more robust. As

with the other forms, however, there is a pronounced depression on the lateral

scapular surface, bounded by a ridge on the posterior edge.

The flat posterodorsal area of the scapular blade probably was the origin of

the scapular deltoid, whereas the more ventral depression may have been the

origin of the scapulo-humeralis anterior. The slenderness of the scapular blade

limits the area available for muscle attachment and neither muscle could have

been particularly well developed. However, the size of the anteroventral

depression, extending as it does along most of the anterior surface of the scapu-

lar blade, provides ample room ventrally for a supracoracoideus attachment,

and it is possible therefore that this muscle has extended its primitive origin on

the coracoid to include part of the scapular blade. In this respect, NMQR 3189

would be more similar to the cynodont condition than the earlier regisaurid

described by Kemp (1986).

The clavicle is a rod-shaped bone that fans out into a large rectangular plate

proximally and into a smaller oval plate distally. Both proximal and distal ends

are covered with numerous fine striations. The shaft of the clavicle is triangular

in cross-section. The length of the clavicle is slightly less than that of the scap-

ula. In overall shape, the clavicle is very similar to that of the baurioid

described by Kemp (1986) but is longer and more delicate. The clavicle of Eri-

ciolacerta was described by Watson (1931) as being a powerful rod of bone; its

proximal end is expanded as in Kemp’s baurioid and NMQR 3189, but it

appears to be somewhat shorter than in either of those two forms. The clavicle

of Cynariognathus is a simple, somewhat robust, paddle-shaped element

according to Cys (1967).

No other part of the ventral shoulder girdle is preserved.

The humerus (Fig. 6) is a slender bone with a distinct shaft. The proximal

and distal ends are at a slight angle to one another. The ends are not well

formed and distinct distal articulatory surfaces cannot be seen. The head of the

bone (Fig. 6—hd) faces proximally as though the humerus took up a sprawling

position at the glenoid. The entepicondylar foramen (Fig. 6—ent.f) is large and

elongated. An ectepicondylar foramen is present. The delto-pectoral crest

(Fig. 6—dpc) is not particularly well developed. The dorsal surface of the distal

end bears a large fossa, presumably for part of the triceps insertion.

The humerus differs very little from that described by Kemp for his

Lystrosaurus—Procolophon Assemblage Zone specimen. Kemp considered that

this humerus was held in a sprawling position. Cynariognathus (Cys 1967),

from the Tapinocephalus Assemblage Zone, is a much larger animal and its

humerus (approximately 180 mm in length) is more robust with well-marked

articular surfaces, but otherwise similar. The humeri of Mirotenthes Attridge,

1956, and Ericiolacerta Watson, 1931, are both very slender and have ends that

386 ANNALS OF THE SOUTH AFRICAN MUSEUM

do not seem to be expanded. Both authors considered that the humerus in these

forms was not held in a horizontal position but was more mammal-like as in

cynodonts.

Fig. 6. The left humerus of NMQR 3189. A. Ventral view. B. Posterior

view. C. Dorsal view. Scale bar = 10 mm.

The right radius and ulna are preserved in situ relative to one another and

with a collection of disarticulated phalanges lying over the ulna. The left

elements have been separated completely, but these are not as well preserved

and appear to have been crushed.

Both radius and ulna are slender, rather delicate bones (Fig. 7). The ulna

has a slight sigmoid curvature. It is markedly flattened anteroposteriorly. The

proximal end of the ulna is expanded mediolaterally and proximally to form a

weak olecranon process. There is a shallow trough on most of the posterior

surface of the proximal end of the ulna. This trough is bounded laterally by a

low rounded ridge. The distal end of the ulna is not expanded.

The radius has a more circular cross-section proximally than that of the

ulna. Both ends of the radius are expanded and the proximal and distal surfaces

are both elongated ovals. The proximal surface is markedly concave, that of the

distal end shallowly concave.

A DESCRIPTION OF THE SKELETON OF A BAURIID THEROCEPHALIAN 387

Fig. 7. The left radius and ulna of NMQR 3189. A. Ulna in anterior

view. B. Radius in anterior view. C. Ulna in posterior view.

D. Radius in posterior view. Scale bar = 10 mm.

Apart from the presence of the weakly developed olecranon process, very

little distinguishes the radius and ulna of NMQR 3189 from those of the other

described therocephalians.

Disarticulated phalanges are preserved close to the right radius and ulna,

and partially articulated digits in situ by the left forearm. Little detail of the

individual bones can be made out. The phalanges are delicate bones, approxi-

mately twice as long as wide, and the unguals are bluntly pointed claws. Very

small phalanges, as illustrated by Cys (1967) for Cynariognathus, are not

present.

PELVIC GIRDLE AND HIND LIMB

The ilia, ischia, femora, tibiae and fibulae are preserved, although no

element is present in its entirety. Some elements of a partially disarticulated foot

are also present. The pelvic girdle has been dorso-ventrally compressed so that

the ilia meet the pubo-ischiadic plates at too small an angle. This distortion has

been corrected in Figure 8C as shown in Figure 8B.

The greater part of the iliac blade is present, although the anterior end is

missing from both right and left ilia, so that the extent of the anterior process is

unknown (Figs 8, 9). The blade is a robust plate of bone bearing a large rec-

tangular posterior process. Shallow concavities are present on the dorso-

posterior part of the iliac blade, and also on what is present of the anterior part.

ANNALS OF THE SOUTH AFRICAN MUSEUM

388

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A DESCRIPTION OF THE SKELETON OF A BAURIID THEROCEPHALIAN 389

The ventral edge of the iliac blade forms the dorsal rim of the acetabulum

with a distinct downwardly projecting lip. Sacral rib facets cannot be seen on

the medial surface.

The ilium closely resembles that of Regisaurus (Kemp 1978) from the

Lystrosaurus Assemblage Zone. The ilium of the baurioid from the same zone

described by Kemp (1986) has a much smaller posterior process, but it is from a

much smaller individual, which Kemp considered to be a juvenile. The ilium of

the immature Ericiolacerta described by Watson (1931) is extremely similar

both in form and size to Kemp’s specimen and Watson made the point that the

shape of the pelvic bones might be different in an adult specimen. It is possible

that the smaller posterior iliac process is a juvenile feature.

Fig. 9. The right ilium of NMQR 3189.

Hatching indicates a covering of matrix.

Broken lines indicate restored outline.

Scale bar = 10 mm.

The posterior parts of both ischia are preserved (Fig. 8). The main body of

the bone is a fairly thin oval plate that is constricted dorsally to form the ischial

contribution to the acetabulum. The posterior edge is broad where it leads

posteroventrally from the acetabulum, becoming thinner more posteroventrally.

A bone, which is probably the right pubis, was present near to the ischia. It

is a rectangular plate of bone, one corner of which is produced dorsally to form

the pubic contribution to the acetabulum. This is damaged in the present speci-

men but appears to have been small. From the acetabular portion, the plate is

cut away to form the anterior edge of the large obturator fenestra. This edge is

very thin, as is the anteroventral edge. The anterodorsal edge leading down

from the acetabulum is thickened. The lateral surface of the plate is convex

anteroposteriorly. Medially it bears a shallow fossa just ventral to the thickened

anterior edge of the bone.

As in Ericiolacerta and the baurioid described by Kemp (1986), the pubo-

ischiadic plate of NMQR 3189 is larger than the ilium, with well-developed

anterior and posterior processes.

There are few indications of muscle attachments on the pelvic girdle. Most

of the iliac blade was presumably covered by the ilio-femoralis, as is typical for

most non-mammalian therapsids (Romer 1922). Whether the pubo-ischio-

femoralis internus attached to the ilium is unclear. The fossa on the medial

surface of the pubis of NMQR 3189 has already been mentioned. It is near to

the thickened anterior edge of the pubis, which is smoothly rounded. There

390 ANNALS OF THE SOUTH AFRICAN MUSEUM

would be no barrier to a muscle that inserted on the medial surface of the pubis

running over the anterior edge and inserting on the femur; this muscle was most

probably the pubo-ischio-femoralis internus.

Kemp (1978) reconstructed the pubo-ischio-femoralis internus attaching on

the lateral surface of the anterior process of the ilium in Regisaurus, whereas in

the baurioid that he described (1986), which had much less-prominent anterior

and posterior iliac processes, he considered that the pubo-ischio-femoralis

internus attached to the medial side of the pubis. In the latter case, it is not clear

what attached to the anterior iliac process. He considered that both of the

animals in question had an essentially similar gait that could operate in both

sprawling and parasagittal modes.

In order for the ventrally attaching pelvic muscles (pubo-ischio-femoralis

internus and pubo-ischio-femoralis externus) to have adequate fibre-length when

the femur is held in its parasagittal stance, the pubo-ischiadic plate must be

oriented almost horizontally, and Kemp (1986) suggested that this was the case

in the baurioid. It is impossible to demonstrate in NMQR 3189 how horizontally

the pubo-ischiadic plate lay, although what reconstruction is possible suggests

that it was not completely horizontal. There is, therefore, no compelling

evidence that this particular animal had the parasagittal component of the dual-

gait suggested by Kemp for the other therocephalians.

Both femora of NMQR 3189 are preserved but the proximal end is not well

preserved on either bone. The femur (Fig. 10) is a slender bone with a gentle

sigmoid curvature. What is preserved of the proximal end of the right femur

indicates that there is a marked recess on the ventral surface, bounded pos-

teriorly by the internal trochanter. It is difficult to assess how prominent the

latter is since the bone is partially crushed. The trochanter major appears not to

be well developed, although it is difficult to be sure of how complete it is. The

head of the bone is not preserved. The distal end is expanded slightly and the

distal condyles are weakly developed. The ventral surface of the distal end bears

a shallow fossa. The shaft is approximately cylindrical in cross-section. The

more complete right femur has a small portion missing from the shaft, so it is

impossible to be certain of the exact orientation of the proximal and distal ends,

but if the preserved position of the bone can be relied on, then the two ends

were at a small angle to one another.

What is present of the femur resembles that of the baurioid described by

Kemp (1986). Without a more complete proximal end, it is difficult to shed any

further light on what kind of posture the hind limb adopted.

The tibia and fibula (Fig. 10) are both very slender, mediolaterally flattened

bones. The smallest width of the tibia is approximately half that of the femur,

that of the fibula approximately one-third that of the femur. The proximal end of

the tibia is strongly expanded with a fairly prominent cnemial crest. The proxi-

mal end of the fibula is slightly expanded.

The pes is represented by the calcaneum and astragalus more or less in situ

distal to the tibia and fibula (Fig. 10), and some separate metatarsals and phal-

anges that may not belong to the same foot. The calcaneum and astragalus are

not well preserved and no details of their articular surfaces, nor a calcaneal

heel, can be seen. Three (possibly four) metatarsals and three phalanges are

present. The three metatarsals that can be definitely identified are relatively

A DESCRIPTION OF THE SKELETON OF A BAURIID THEROCEPHALIAN 391

Fig. 10. The left femur, tibia and fibula of NMQR 3189. A. Distal part of femur in

dorsal view, tibia and fibula in medial view. B. Tibia and fibula in lateral view.

C. Distal part of femur in ventral view. Hatching indicates presence of matrix.

Scale bar = 10 mm

long: approximately two-and-a-half times the length of the phalanges. The

fourth possible metatarsal is much smaller and could therefore be either meta-

tarsal I or II, or possibly a phalanx; the disarticulated state of the pes makes it

impossible to tell which.

One ungual phalanx is present. It is bluntly pointed and approximately the

same size as the unguals of the manus. What is preserved of the pes agrees

broadly with that of Bauria cynops described by Broom (1937), Boonstra (1938)

and Schaeffer (1941), although it is only two-thirds the length of that specimen.

CONCLUSION

The postcranial skeleton of the late therocephalian described here shows

some similarities with the earliest members of that group such as Cynario-

gnathus. The latter form, from the Tapinocephalus zone (Cys 1967), is a larger

animal than NMQR 3189, but the structure of the vertebral column and ribs is

392 ANNALS OF THE SOUTH AFRICAN MUSEUM

essentially similar, including the abrupt transition in the posterior dorsal ribs.

The scapula is also similar in bearing a depression on its lateral surface bounded

by a ridge.

However, some differences between the two forms are also apparent. The

humerus of Cynariognathus is a much more robust bone (although this might be

expected in a larger animal) with more expanded ends and a shorter shaft region

than in NMQR 3189 or the Lystrosaurus-zone regisaurid. The manus does not

show the very small phalanges present in Cynariognathus, which appear to be a

specialization of the Tapinocephalus-zone therocephalians.

The ilium of Cynariognathus is not well preserved, but Cys (1967) noted

that it probably had little anterior extension. In the pristerognathid thero-

cephalians described by Boonstra (1964), the anterior extension varies from

being sharp and pronounced (Cynariognathus, unidentified pristerognathid) to

undeveloped (Pristerognathoides). This feature cannot be verified in

NMQR 3189, but in Regisaurus and the regisaurid described by Kemp, there is

a pronounced anterior extension of the ilium. The obturator fenestra is thought

to be a small perforation in Cynariognathus, whereas in NMQR 3189 (if the

pubis has been identified correctly) the fenestra is large. It is also large in the

regisaurid specimen.

Some of these features (e.g. the presence or absence of an anterior extension

of the ilium) are obviously concerned with the changing of muscle attachments,

but what this means in terms of evolution of locomotory ability within the group

must await an in-depth functional study of therocephalian postcrania.

ACKNOWLEDGEMENTS

I am grateful to Mr J. Welman (National Museum, Bloemfontein) for bring-

ing this specimen to my notice and making it available for study. Mr C. Booth

(South African Museum, Cape Town) provided the photographs and Mr C.

Hunter (South African Museum, Cape Town) drew the figures. Mrs J. Goodall

(South African Museum, Cape Town) prepared the specimen. Prof. J. A.

Hopson, Dr T. S. Kemp and Dr B. S. Rubidge all provided valuable comments

on the manuscript. I am indebted to all these colleagues.

REFERENCES

ATTRIDGE, J. 1956. The morphology and relationships of a complete therocephalian skel-

eton from the Cistecephalus zone of South Africa. Proceedings of the Royal Society of

Edinburgh (Section B) 66 (1): 59-93.

BoonstrA, L. D. 1938. Ona South African mammal-like reptile, Bauria cynops. Palaeo-

biologica 6: 164-183.

BoonsTrRA, L. D. 1964. The girdles and limbs of the pristerognathid Therocephalia. Annals

of the South African Museum 48 (5): 121-165.

Broom, R. 1906. On anew cynodont reptile (Aelurosuchus browni). Transactions of the

South African Philosophical Society 16 (4): 376-378.

Broom, R. 1937. On the palate, occiput and hind foot of Bauria cynops Broom. American

Museum Novitates 946: 1-6.

Cys, J. M. 1967. Osteology of the pristerognathid Cynariognathus platyrhinus (Reptilia:

Theriodontia). Journal! of Paleontology 41 (3): 776-790.

A DESCRIPTION OF THE SKELETON OF A BAURIID THEROCEPHALIAN 393

Gow, C. E. 1978. The advent of herbivory in certain reptilian lineages during the Triassic.

Palaeontologia africana 21: 133-141.

Hopson, J. A. & BARGHUSEN, H. R. 1986. An analysis of therapsid relationships. Jn:

HoTTon, N., MACLEAN, P. D., Rotu, J. J. & Rotu, E. C. eds. The ecology and

biology of mammal-like reptiles: 83-106. Washington: Smithsonian Institution Press.

Kemp, T. S. 1978. Stance and gait in the hindlimb of a therocephalian mammal-like

reptile. Journal of Zoology, London 186: 143-161.

Kemp, T. S. 1982. Mammal-like reptiles and the origin of mammals. London: Academic

Press.

Kemp, T. S. 1986. The skeleton of a baurioid therocephalian therapsid from the Lower

Triassic (Lystrosaurus zone) of South Africa. Journal of Vertebrate Paleontology 6 (3):

215-232.

KITCHING, J. W. 1977. Distribution of the Karroo vertebrate fauna. Memoirs of the

Bernard Price Institute for Palaeontological Research 1: 1-131.

RoMER, A. S. 1922. The locomotor apparatus of certain primitive and mammal-like

reptiles. Bulletin of the American Museum of Natural History 46: 517-606.

RusipcE, B. S. 1990. A new vertebrate biozone at the base of the Beaufort Group, Karoo

Sequence (South Africa). Palaeontologia africana 27: 17-20.

RuBIDGE, B. S. (in press). Biostratigraphy of the Eodicynodon Assemblage Zone. In:

RuBIDGE, B. S. ed. Biostratigraphy of the Beaufort Group (Karoo Sequence), South

Africa. Pretoria: Government Printer.

SCHAEFFER, B. 1941. The pes of Bauria cynops Broom. American Museum Novitates 1103:

1-7.

VAN DEN HEEVER, J. A. 1987. The comparative and functional cranial morphology of the

early Therocephalia (Amniota: Therapsida). Unpublished Ph.D. thesis, University of

Stellenbosch, South Africa.

Watson, D. M. S. 1931. On the skeleton of a bauriamorph reptile. Proceedings of the

Zoological Society of London 1931 (2): 1163-1205.

ABBREVIATIONS

as — _astragalus is — ischium

ca — calcaneum j — lower jaw (dentary)

cc — cnemial crest ma — manus

cl — clavicle mt — metatarsals

dep — depression on scapula pt —_ proximal tarsals

dpc — _ delto-pectoral crest of humerus Ta — radius

ent.f — entepicondylar foramen of humerus ri —_ scapular ridge

fe — femur sc — _ scapula

fi — fibula t — _ tooth

fs — flat surface of scapula ti — tibia

hd — _ head of humerus ul — ulna

hu — humerus vy —_ vertebra

il — ilium ve — _ vertebrae

6. SYSTEMATIC papers must conform to the International code of zoological nomenclature (particu-

larly 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. nov., 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 trans-

ferred 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 specimens

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, descrip-

tion 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 Eliza-

beth (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. DuToit 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 preferably 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. The generic name should

not be abbreviated at the beginning of a sentence or paragraph.

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.