Museum of Comparative Zoology Breviora 09

^^s7
BREVIORA

MUSEUM OF COMPARATIVE ZOOLOGY
Harvard University

NUMBERS

351-379

1970-1971

CAMBRIDGE, MASSACHUSETTS,
1971

U.S.A.


Edited

by
Penelope Lasnik


CONTENTS
BREVIORA
Museum of Comparative Zoology
Numbers 351-379
1970
No. 351.

A

new species in the nomeid fish genus Psenes from
the equatorial eastern Pacific. By Richard L. Haedrich. 7 pp. June 12.

No. 352. The Chaiiares (Argentina) Triassic

The

skeleton

postcranial

of

reptile

the

fauna VII,

traversodontid

Massetognathus pascuali (Therapsida, Cynodontia).
By Parish A. Jenkins, Jr. 28 pp. July 10.
No. 353. Anolis jacare Boulenger, a solitary anole from the
Andes of Venezuela. By Ernest E. Williams, Osvaldo
A. Reig, Pablo Kiblisky, and Carlos Rivero-Blanco.
15 pp.

10.

August

No. 354. Taxonomic and ecological notes on some Middle and
South American lizards of the genus Ameiva
9 pp.
(Teiidae).
By Arthur C. Echternacht.
18.

September

No. 355. Generic relations and speciation patterns in the Caracaras (Aves: Falconidae). By Francois Vuilleumier.

29 pp. November 30.
No. 356.

On

a

new

Rico.

No. 357.

A

review

species in a new
By G. E. Gates.

of

the

fossil

Pleurodira) of Asia.
pp.

November

earthworm genus from Puerto
11 pp.

November

Pelomedusidae

30.

(Testudines,

By Roger Conant Wood.

24

30.

No. 358. South American anoles: Anolis apollinmis Boulenger
1919, a relative of A. biporcatus Wiegmann (Sauria,
Iguanidae).

November

30.

By

Ernest

E.

Williams.

11

pp.


No. 359. The swimbladder as a juvenile organ
fishes.
By Michael H. Horn. 9 pp.
No. 360.

Mammals from

in

stromateoid

November

30.

the early Cenozoic of Chubut, Argen1 3 pp.
Novem-

By George Gaylord Simpson.

tina.

ber 30.
to knowledge of the Argyrolagidae (MamMarsupialia) from the late Cenozoic of
Argentina.
By George Gaylord Simpson. 9 pp.

No. 361. Additions
malia,

November

30,

knowledge of Groeberia (Mammalia,
Marsupialia) from the mid-Cenozoic of Argentina.

By George Gaylord Simpson. 17 pp. November 30.

No. 362. Addition

to

1971
No. 363. Non-specificity of
snail

tropoda:

Pyramidellidae).
7 pp.
J. Boss.

and Kenneth
No. 364.

A

new

scincid

Islands.

January

By

in the ectoparasitic
bisuturalis (Say) (Gas-

host-selection

Odostomia (Menestho)

lizard

from

By Robert
January

C.

Bullock

8.

Solomon

Bougainville,

Allen E. Greer and Fred Parker.

1 1

pp.

8.

No. 365. Characters and synonymies among the genera of ants.
Part IV.
Some genera of subfamily Myrmicinae
(Hymenoptera: Formicidae). By William L. Brown,
5 pp.
Jr.
January 15,

No. 366. Pulsed sound of the porpoise Lagenorhynchus australis.
By William E. Schevill and William A. Watkins. 10
pp.

January 15.

No. 367. Micromischodus sugillatus, a new hemiodontid characin
fish from Brazil, and its relationship to the Chilodontidae.
By Tyson R. Roberts. 25 pp. January
15.

No. 368. Structural habitats of West Indian Anolis

Lowland

Jamaica.

Schoener.

53 pp.

No. 369. Lithophaga

Thomas

W.

lizards

I.

and

Amy

aristata in the shell-plates of chitons

(Mol-

By

January 29.
C. Bullock and Kenneth

lusca).

By Robert

10 pp.

January 29.

J.

Boss.


observations on a little known South
American anole: Tropidodactyliis onca. By James

No. 370. Ecological

No. 371.

A

new

March

6 pp.

P. Collins.

species

of

Anguidae)

(Sauria:

Schwartz.

10 pp.

31.

bromeliad-inhabiting
galliwasp
from Jamaica.
By Albert

March

31.

No. 372. The paleontology and evolution of Cerion II: age and
fauna of Indian shell middens on Curacao and Aruba.
By Stephen Jay Gould. 26 pp. March 31.

No. 373. The Chanares (Argentina) Triassic

reptile fauna. VIII.
skull
of
a
fragmentary
large thecodont, Liiperosuchus fractus. By Alfred Sherwood Romer. 8 pp.

A

March
No. 374. The

31.

fishes

of

the

(Atheriniformes).

Malaysian

By Tyson

family Phallostethidae
R. Roberts.
27 pp.

June 15.
No. 375. Structural habitats of West Indian Anolis lizards II.
Puerto Rican uplands.
By Thomas W. and Amy
Schoener.
39 pp. June 15.

No. 376. Podocnemis venezuelensis,

a

new

fossil

pelomedusid

from the Pliocene of
Pleurodira)
Venezuela and a review of the history of Podocnemis
(Testudines,

South America.
By Roger Conant Wood and
Maria Lourdes Diaz de Gamero. 23 pp. June 15.
in

No. 377. The Chanares (Argentina) Triassic reptile fauna IX.
The Chaiiares Formation.
By Alfred Sherwood
Romer. 8 pp. June 15.
No. 378. The Chanares

(Argentina) Triassic reptile fauna X.
but incompletely known long-limbed
pseudosuchians.
By Alfred Sherwood Romer. 10

Two new
pp.

June

15.

No. 379. The Chanares (Argentina) Triassic

Two new

reptile

fauna

XL

long-snouted thecodonts, Chanaresuchus
and GuaiosLichus. By Alfred Sherwood Romer. 22

pp.

June

15.


INDEX OF AUTHORS
BREVIORA

Museum

of Comparative Zoology

Numbers 351-379
1970-1971

No.
Boss,

Kenneth

363, 369

J

Brown, William, Jr

365

C

363, 369

Bullock, Robert
Collins, James P

370

Diaz de Gamero, Maria Lourdes

376

Echternacht, Arthur C

354

Gates, G. E

356

Gould, Stephen Jay

372

Greer, Allen E

364

Haedrich, Richard L

351

Horn, Michael

H

359

Jenkins, Parish A., Jr

352

KiBLisKY, Pablo

353

Parker, Fred

364

Reig, Osvaldo

a

Rivero-Blanco, Carlos

353
353


No.

Roberts, Tyson

R

367^ 374

RoMER, Alfred Sherwood

ScHEviLL, William

373. 377, 378, 379

E

Schoener, Thomas W. and

366

Amy

Schwartz, Albert

37I

Simpson, George Gaylord

360, 361, 362

Vuilleumier, Francois
Watkins, William

368. 375

355

A

{j'li^^^''''

366

.



BREVIORA
Mmseuim of Compsirative Zoology
Cambridge, Mass.

A NEW

12

SPECIES IN THE

Number

June, 1970

NOMEID

GENUS PSENES

FISH

FROM THE EQUATORIAL EASTERN
Richard

L.

351

PACIFIC^

Haedrich-

Abstract. Psenes sio n. sp. is based on five specimens 23-66 mm SL
from the equatorial eastern Pacific Ocean. The new species belongs to the
species-group (others are P. pelliicidiis, P. maculatus, and P. arafurensis)
with large, laterally compressed, knifelike teeth in the lower jaw. P. cyanophrys and P. whiteleggii have small conical teeth in both jaws. The new
species is characterised by its light color, long pelvic fins, two weak anal
spines

and 23-24

rays,

18-19 pectoral finrays, and 36-38 vertebrae.

In a recent unpublished yet widely distributed manuscript
(Haedrich and Horn, 1969), a new species of Psenes was included
in a key (p. 36). It was stated explicitly that use of the name in
the key did not constitute publication, and it was indicated that a
formal description would soon appear in a review of the entire
genus. Other responsibilities, however, have virtually brought this
work to a halt, and early completion of the review does not seem
likely. Therefore, in order to avoid the nomenclatural debacle that
I see developing, this note has been prepared describing the new

species.

based were made
Zoologiske Museum, Copenhagen (ZMC). They were collected by
Dr. Nielsen on Step-I, a cruise conducted by the Scripps Institution
of Oceanography. The manuscript has been read by Richard H.
Backus and Giles W. Mead. Figure 1 was drawn by E. Leenders.

The specimens upon which

available

the

new

species

by J0rgen Nielsen, and are housed

is

in Universitetets

Contribution No. 2486 from the Woods Hole Oceanographic Institution.
Woods Hole Oceanographic Institution, Woods Hole, Mass., and
Museum of Comparative Zoology, Harvard.
1

2

No. 351

BREVIORA

2

Portions of this work were supported by a United States Government Grant under the Fulbright-Hays Act, the Johs. Schmidt
Fund, and National Science Foundation grant GB- 15764.

stromateoid

fishes, the

genus Psenes

is distinguished in
dorsal originating over or
before the pectoral insertion, persistent thoracic pelvic fins, a deep

Among

having two dorsal

fins

with the

first

moderately elongate body, and teeth present in some species on
and/or basibranchials but never on the glossohyal.
The genus, its relationships, and the nominal species were treated
in a general way by Haedrich (1967), though recent findings will
modify this account somewhat. Within Psenes, there seem to be
to

the palatines

two species groups.

One group

(including P.

cyanophrys and

P. whiteleggii) is characterized by small, conical, slightly recurved
teeth in both the upper and lower jaw. The other group (including P. pellucidus, P. arajurensis, P. maciilatus and the new

has small, conical, slightly recurved teeth in the upper
large, laterally flattened, bladelike teeth in the lower jaw.
In recognition of the considerable contributions to marine ich-

species)

jaw and

thyology

made by the Scripps
known as

Institution of

Oceanography, the new

species will be

Psenes sio

1

Figure
Material.

Five specimens, 23-66

marked with an

n. sp.

mm

SL,

all

in

ZMC;

asterisk* have been X-rayed: *1 spec,

60

those

mm

SL,
11°10'S 80°01'W, 17 Oct. 1960,
2250-2345 hrs., 0-90 m, 5' net, surf. temp. 17.8°C. PARATYPES: *1 spec, 66
SL, Step-I sta. 80-1, 1°24'S 94°55'W,
2/3 Dec. 1960, 2335-0230 hrs., high-speed net, battered. 2 spec,
26 & 44 mm SL, Step-I sta. 73-1, 4°22'S 95°04'W, 2 Dec. 1960,

HOLOTYPE,

Step-I

sta.

23,

mm

0200-0500

smaller spec,
hrs., high-speed net, very battered,
cleaned-and-stained. *1 spec, 23
SL, Step-I sta. 80, 1°59'S
94°55'W, 2 Dec. 1960, 2200 hrs., dipnet-nightlight, surf. temp.

mm

22°C. All specimens are immature.
Diagnosis. An elongate, compressed, light-colored Psenes with
large, compressed close-set teeth in the lower jaw, long pelvic fins,
two weak anal spines and 23-24 rays, and 36 to 38 vertebrae.
Description. Individual proportions and counts are presented in
Table 1.

The body

is

elongate, the

maximum

depth of larger specimens


1970

NEW NOMEID

FISH

3

being around 30 per cent of the standard length, and is very compressed. The caudal peduncle is tapered, compressed, and some-

what elongate. The musculature, though firm, is translucent, particularly along the anal fin base and over the viscera. The two
dorsal fins are scarcely divided. The first dorsal fin originates over
the edge of the opercle and comprises 10 to 12 thin brittle spines,
the second originates just behind mid-body and comprises 23 to 25
long rays. The entire fin folds partially into a very shallow groove
and terminates behind the end of the anal fin. The anus is at midbody, in a slit. The anal fin commences shortly behind the anus

under the third or fourth ray of the second dorsal, and is composed
of two weak spines and 23 or 24 long rays. The muscles for elevating the anal rays can be clearly seen, as can the basal elements
of both median fins. The pectoral fin is long and fairly broad, with
18 or 19 rays; its base is incUned about 45° to the vertical. The
pelvic fins are very long; they insert under the middle or end of
the pectoral fin base and extend beyond the anal origin, and are
composed of one short spine and five long branched rays. The
caudal fin, broken in most specimens, is apparently long and
forked; the small elements preceding the principal rays extend
well forward on the peduncle. The cycloid scales are very small,
and do not appear to extend significantly onto the bases of the
median fins. The scales are extremely deciduous, and most are
gone; the count of scale pockets along the lateral line of the holotype is ca. 85. The skin is thin; the subdermal mucus canal system
is but httle developed, and the body pores are very small or
wanting.

The head is around 35 per cent of the standard length, its profile

The skin of the top of the head is naked, and pores are
clearly visible, particularly those over the head of the hyomandibular.
The eye is of moderate size, located a little more than its
diameter from the tip of the truncate snout, and does not enter
sloping.

into the profile of the head. There is apparently
around the eye, but somes does extend forward

no adipose tissue
from the front of

the eye to surround the nostrils. The two small nostrils are located
much nearer to the tip of the snout than to the eye. The end of

the maxillary is below the anterior border of the eye, but the angle
of the gape is well before the eye. The premaxillary is not pro-

The lacrimal bone is large and transparent, and covers
the top of the maxillary. The teeth are uniserial in the jaws. The
teeth in the upper jaw are small, conical, slightly recurved, and
spaced; the teeth in the lower jaw are large, at least twice as long

tractile.


No. 351

BREVioRA

4

upper jaw, compressed and knifeUke with very small
and
very close-set. The vomer, palatines, and basibranchials
cusps,
be
toothless. The oral valves are prominent. The operto
appear
cles are very thin; their margins are either entire or set with extremely fine spinules. The striated opercle has two very weak flat
spines; the angle of the preopercle is rounded but does not bulge
backward. The gill-rakers are moderate, blunt, about half the
length of the filaments, and bear fine teeth on their inner edges; the
rakers are spaced, about 15 on the lower limb of the first arch.
The pseudobranch is well developed, but there are no rudimentary
rakers below it. The light yellow thymus is clearly visible. There
as those in the

are six branchiostegal rays.
The color in alcohol is tan, darker

on

the

back than on the

sides.

a suggestion of three brownish vertical bands on the after

of
the
part
body in some specimens. The first dorsal fin is dark,
but all the other fins are whitish. The dark lining of the gill cavity

There

is

shows clearly through the transparent opercles. The dark peritoneum shows clearly through the thin abdominal wall. The inside of the mouth is fight yellow, and the eye is grey.

The skeleton in general is very light. This is particularly apparent in the thin transparent dermal skeleton. There is no supramaxillary bone. The supraoccipital is but little developed. There
is a wide opening between the cleithrum and the coracoid.
The
pelvic bones reach to the cleithrum. There is a large foramen in
the scapula. The postcleithrum can be plainly seen through the
body wall, and it extends to the lower margin of the body. There
are 36 to 38 vertebrae, including the hypural; about 12 to 15 vertebrae appear to be precaudal. In the tail, there are two autogenous
haemal spines, four hypurals, two paired uroneurals, and three
epurals. The second and third hypurals are broad triangular plates
much larger than any other caudal element. The first hypural bears

an hypuropophysis. Three free interneurals precede the dorsal

The

first

dorsal interneural supports two spines.

The two

fin.

anal

spines are weak.

Remarks. Most species of P series are widely distributed in the
and sub-tropical parts of the world ocean. P. sio, however, is quite restricted, and has been found only in the eastern
Pacific from about 11° S (holotype) to perhaps 10° N (R. Rosenblatt, additional Scripps specimens, in lift.). P. sio most closely
tropical

resembles P. rnaculatus, an apparently antitropical species known
only from sub-tropical waters in the North and South Atlantic.
Within the range of Psenes sio, only P. cyanophrys is known to
occur for sure. This species may be distinguished from P. sio


NEW NOMEID

1970

FISH

5

its small conical teeth that are similar in both jaws (as mentioned above), its color pattern of fine horizontal stripes (P. sio
has about three indistinct vertical bands), its greater maximum

by

depth (43-52% SL
number of median

vs.

29-41% SL in P.
rays (D 24-29

sio),

its

generally greater

A 24-28 vs.
fewer
vertebrae
v^.
and
its
(31
36-38).
23-24),
As yet unrecorded from the eastern tropical Pacific but known
from the western parts of that ocean are Psenes pellucidus and
P. arafurensis. The former has more median finrays and vertebrae (D 27-32, A 26-31, vert. 41-42) than P. sio, the latter fewer
fin

vs.

23-25,

18-22, A 20-22, vert. 31).
Psenes whiteleggii, from the Indian Ocean and Australia, has
conical teeth in both jaws and low median finray and vertebral
counts (D 17-20, A 17-18, vert. 31-32). The Atlantic P. maculatus, the species most similar to P. sio, has slightly fewer median

(D

finrays

and vertebrae (D 22-24,

A

22-24, vert. 35)

and more

pectoral finrays (21-22 vs. 19 in P. sio) and anal spines (III vs.
II). The preanal distance is 58-63% SL in P. maculatus, and

51-54% SL

in P. sio.

LITERATURE CITED

Haedrich, Richard L.
classification.

Haedrich, Richard
stromateoid

1967.

Bull.
L.,

fishes.

69-70, September

The stromateoid

Mus. Comp.

and Michael H. Horn.

1969.

Woods Hole Oceanographic
1969, 46 pp.

(Received 2 April 1970.)

systematics and a
135(2): 31-139.

fishes:

Zool., Harvard,

A

key to the
No.

Institution Ref.

Unpublished Manuscript.


BREVIORA

6

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No. 351


1970

NEW NOMEID

FISH

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BREVIORA
Miiseimi of

Zoology

Cointipairsitive

Cambridge. Mass.

Number

10 July, 1970

352

CHANARES (ARGENTINA) TRIAS5IC REPTILE FAUNA

THE P05TCRANIAL SKELETON OF THE TRAVERSO-

THE
VII.

MASSETOGNATHUS PASCUALI
CYNODONTIA)

DONTID

(THERAPSIDA,

Parish A. Jenkins, Jr.^
Abstract. The postcranial skeleton of Massetognathus pascuali is
described from a single nearly complete individual and four disarticulated
specimens; manus, pes and pubis could not be described from the available

M.

material.

pascuali has a postcranial skeleton morphologically similar to

that in Pascualgnathns polanskii (an earlier traversodontid)

Triassic cynodonts.

from that

in

The

Exaeretodon

and

in

African

basic skeletal pattern of all these forms differs
sp.,

an advanced traversodontid. The specialized,

imbricating ribs of M. pascuali are intermediate in form between those
of P. polanskii (which are diademodontid in form) and those of Exaere-

todon

sp.

(which essentially have

lost the

cynodont specialization).

Although Richard Owen made the first study of a cynodont more

than a century ago, a detailed knowledge of cynodonts has accumulated only recently. First known only from Africa, representatives
have

now been

recovered from Asia and North and South America.

The most

of this

advanced group of mammallike

reptiles

specialized and, during the early and middle Triassic, the most
abundant cynodonts were the herbivorous gomphodonts. Transversely broad, multicuspid postcanine molars with heavy occlusal
wear (often to the point of effacing the original crown pattern)
are characteristic of the group. Romer (1967) recognized three

Diademodontidae, Traversodontidae, and
Massetognathus pascuali is a traversodontid
one of two species described by Romer (1967) from the

gomphodont

families:

Trirhachodontidae.

and

'

is

Department
York 10032

of

Anatomy,

Columbia

University,

New

York,

New


No. 352

BREVIORA

2

Chanares Formation of Argentina. Other undoubted traversodontid genera include Traversodon from the Santa Maria Formation of
Brasil, Exaeretodon, Proexaeretodon and Ischignathus from the
Ischigualasto Formation of Argentina, and Scalenodon and Scalenodontoides from the Manda and Molteno beds, respectively, of
Africa. Pasciialgnathus polanskii from the Puesto Viejo Formation of Argentina, originally classified as a diademodontid (Bonaparte, 1966a; 1966b), is now interpreted as a primitive traversodontid on the basis of tooth morphology (Bonaparte, 1967, and

personal communication).
The present account of the Massetognathus pasciiali postcranial
skeleton is based upon the disarticulated remains of at least four
individuals and an almost completely articulated skeleton of a fifth
individual,

all

about the same

size

and preserved

in a

nodule several

inches thick and two and one-half feet in diameter. The 1964-65
expedition of the Museo de la Plata and Museum of Comparative

Zoology collected the nodule from the Chanares Formation in the
Chanares-Gualo region of western Argentina. All the skeletal
material is catalogued as No. 3691 in the Museum of Comparative

Zoology.

Although the available postcranial material of Massetognathus
pasciiali is incomplete, there are two reasons why even a partial
account is important. First, some workers regard cynodonts as
ancestral to mammals (Crompton and Jenkins, 1968; Hopson and

Gomphodont cynodonts are certainly not
mammals, but they undoubtedly possessed a

di-

Crompton, 1969).
rectly related to

de-

gree of biological organization that at least approximated that of
their carnivorous-insectivorous relatives (from some form of which

mammals were

derived). Thus

all

cynodonts are relevant to evalu-

ating the reptile-mammal transition. Second, most published investigations of cynodonts have been restricted to cranial anatomy.

Well-preserved, generically determinate postcranial skeletons are

Of South American genera, only Belesodon (von Huene,
1935-1942), Exaeretodon (Bonaparte, 1963a) and Pasciialgnathus are known from relatively complete skeletons; the preservation
of known Belesodon material is poor, however, and Exaeretodon
rare.

appears to be morphologically aberrant in comparison to the genpattern known from other cynodonts. Postcranial material
associated with Traversodon and Chiniquodon (von Huene, 1935
1942) is only fragmentary, although Romer (1969) has recently
described more complete limb bones of Chiniquodon. I have reeral

viewed the postcranial skeletons of African cynodonts (Jenkins,

in


MASSETOGNATHUS POSTCRANIAL SKELETON

1970

press). Of the Russian forms very little is known;
available for Permocyiiodon (Konjukova, 1946).

some data

is

Vertebral column and ribs

The number

of presacral vertebrae in Massetognathus pascuali
23 and is here interpreted to be about 26. A hiatus in
the lumbar series of the one nearly complete, articulated vertebral
is

at least

column

is responsible for this uncertainty.
Present are 7 cervicals,
164-? dorsals, and 6 sacrals. Judging from the length of several
articulated but incomplete caudal series, tail vertebrae numbered
at least 17 and probably as many as 25. A count of 26 presacral
vertebrae in M. pascuali compares with 26 in Leavachia duven-

hagei (Broom, 1948), 27 in Thrinaxodon liorhinus (Jenkins, in
press), 28 in Exaeretodon sp. (Bonaparte, 1963a), 29 in Cynognathus crateronotus (Seeley, 1895 ) and at least 30 in a large cyno-

dont identified tentatively as Diademodon

sp.

(Brink, 1955; Jen-

kins, in press).

Two separately articulating atlas arches appear to conform to

the general pattern known from African Triassic cynodonts (Jenkins, in press), but their preservation is too poor to allow specific
description or comparison. The atlas intercentrum. transversely
elongate and ventrally convex, bears a posteriorly directed process

A

concave articular facet on the dorsal surlip (1, Fig. IB).
face of this lip contacts a median convex facet on the anterior
or

The lateral extremities
aspect of the atlas centrum (f a i, Fig. 6B )
of the intercentrum each bear, on their dorsal surfaces, a concave
.

facet that articulates with the ventral aspect of one of the two
occipital condyles. The atlas centrum (6
long) is synostosed

mm

Vertebral elements in Massetognathus pascuali. A. Cervical
Figure 1.
vertebrae, probably the third and fourth, in lateral view. B. First or atlantal
intercentrum in ventral view with anterior margin toward the top of the
page.

C, Anterior dorsal ("thoracic")

vertebrae; vertebra on the right

is

posterolateral view. All X 1. Abbreviations:
fo, costal fovea for rib head; 1. posterior lip of the intercentrum; p. para-

in

lateral view,

pophysis;

t,

on the

left

transverse process.


No. 352

BREVIORA

4
centrum (8.5

mm

long), forming a conspicuously large
the dorso-lateral aspects of the atlas centrum are two
facets, one for each atlas arch half (f a a. Fig. 6B). Protruding
from the median aspect of the centrum between these facets is a
to the axis

vertebra.

On

small process (d, Fig. 6B) homologous with the dens or odontoid
process of mammals. Elsewhere (Jenkins, 1969; in press) I have
proposed that the mammalian dens originated as a neomorphic
process from the atlas centrum of cynodonts. The occurrence of a

dens in Massetognathus pascuali is unequivocal and supports the
theory that both a dens and an atlas centrum (of which the dens
was formerly thought to be a vestige) occur together among
cynodonts.

The
9

axis

centrum of the one articulated cervical

mm long, mm longer than
1

series is

about

the centra of the following cervicals.

The axial prezygapophyses have been broken off on all specimens,
but from the appearance of their narrow bases^ no thicker than
the laminae from which they protrude
they are vestigial. Axial
postzygapophyses of normal size bear articular facets at an angle
estimated to be 25° to the horizontal. The axial spine, a flat blade
with a distinctly mammalian shape, exhibits a straight dorsal mar-

—

—

gin that was probably slightly convex during hfe. The robust
transverse processes are directed posterolaterally.
Cervical centra are amphicoelous, as are all other centra in

Massetognathus pascuali, with the exception of the atlas (only the
posterior aspect bears a notochordal concavity) and possibly some
of the smaller caudal vertebrae. In cervical vertebrae, the rim surrounding the notochordal concavity on each end is swollen, and
this increases the concave curvature of the sides and ventral aspect
of each centrum. A bulbous parapophysis is to be found on the
ventrolateral aspect of each anterior rim (p. Fig. lA). If the rib
head articulated on the apex of the parapophysis, as seems most
likely on the basis of the large size of the process, then this condition differs from that in species of Thrinaxodon and Cynognathus,

in which cervical rib heads are situated intervertebrally. A median
ventral keel, similar to that in other cynodont cervicals, traverses
the length of each cervical centrum.

Cervical pedicles are narrow anteroposteriorly and bear short,
stout transverse processes (t, Fig. lA). Cervical spines, broken

on all but two disarticulated cervicals (Fig. lA), are transversely slender and recurved, and taper abruptly toward the apex.
Of particular interest are the zygapophyses, which provide a basis
for distinction between cervical and dorsal (anterior thoracic)
off

vertebrae.

As noted

above, the axial postzygapophyseal facets are


MASSETOGNATHUS POSTCRANIAL SKELETON

1970

5

oriented at an angle of about 25° to the horizontal; the orientation
of posterior facets on the third through sixth cervical are more than

25°

—probably about

35°.

The

distance between their lateral mar-

approximately 7 mm. The anterior articular facets of the
seventh cervical of course conform in orientation and spacing to

gins

is

those of the foregoing series. The posterior articular facets, howappear to be oriented at about 45°. Those on the succeeding

ever,

—

i.e., within a few de(eighth) vertebra are nearly parasagittal
of
and
3.5
vertical
are
apart. The articular facet
grees
only

—

mm

of the eighth vertebra, continued (with gradual
modification) through the dorsal series, definitely estabhsh a different pattern. Although transitional, the seventh vertebra most
characteristics

and thus may be regarded
in facet orientation and
with
other
together
spacing,
morphological changes, occur between
the seventh and eighth vertebrae of Tlvinaxodon liorhimis and

closely resembles other neck vertebrae
Similar changes
as the last cervical.

Cynognathiis craterouotiis (Jenkins, in press).

Massetognathus pascuali reaffirms the

number

of seven cervical vertebrae

The condition in
"mammalian"

fact that the

was already established

in

cynodonts.

With

the exception of the atlas intercentrum,

intercentra have been identified.

no other cervical

The broad grooves formed by

the

—

rims of adjacent centra are evidence that intercentra were present
as in Thrinaxodon liorhimis, for example
and the state of disarticulation accounts for their postmortem loss.

—

The dorsal

vertebral

column

in

cynodonts

is

either a relatively

—

undifferentiated dorsal series (as in most reptiles) or two series
"thoracic" and "lumbar" (as in mammals). In certain African

Triassic cynodonts, separation of thoracic and lumbar regions may
be made on the basis of distinct morphological specializations of

(= lumbar) ribs (Jenkins, in press). In other
cynodonts (e.g., Exaeretodon sp.; Bonaparte, 1963a) the trunk
cannot be divided into thoracic and lumbar regions because the
posterior ribs are not specialized. Massetognathus pascuali has
specialized "lumbar" ribs and clearly belongs to the first category.
The exact number of thoracic and lumbar vertebrae is unknown
because a complete vertebral column with ribs is not yet available.

Therefore, thoracic and lumbar vertebrae will be given only a
the posterior dorsal

general description as anterior and posterior dorsals, respectively,
although the ribs (to be discussed below) clearly give evidence of
a differentiated series.

The centra

mm

of anterior dorsal vertebrae are approximately 8.5

long; those of posterior dorsals are about

1 1

mm long

(10

mm


BREVIORA

6
in the

No. 352

one articulated specimen). The costal foveae

(fo. Fig.

IC)

of anterior dorsal vertebrae form a cleft for reception of the rib
head, which is therefore intervertebral in position. On posterior
dorsals the rib head articulates with a parapophysis (p, Fig. 2B)
and is not intervertebral. Transverse processes are laminar and

bowed

dorsally on anterior dorsal vertebrae (t, Fig.
rodlike and round in cross-section on posterior dorsals

The

IC) but are
(t, Fig. 2B).

posterior intervertebral notch

is deep throughout the dorsal
notch negligible or absent. In contrast to many
cynodonts, anapophyses are lacking. Dorsal prezygapophyses are
robust, extending to or slightly beyond the level of the anterior
aspect of the centrum. Articular facets on the first dorsal vertebra
are about 3.5

apart and on the ninth are 4.0 mm; an abrupt
widening takes place at some point in the middle or posterior dorsal

series, the anterior

mm

series, for the articular facets of the

are about 7

mm

apart.

penultimate dorsal vertebra

The narrowly-spaced

facets of anterior

dorsals are nearly vertical, whereas those wider apart on the posterior dorsals are oriented at angles of as much as 45°. Neural

spines on anterior dorsals are narrow, but unlike cervical spines,
do not taper significantly at the apex; they incline caudad at angles
of about 30°. Spines on posterior dorsal vertebrae are broad anteroposteriorly, leaving only a narrow gap between vertebrae; their
inclination is only a few degrees caudad.
Sacral vertebrae successively decrease in size posteriorly. The
centrum of the first sacral is approximately as long as those of the
posterior dorsals (about 10 mm), while the sixth and last sacral

centrum is some 2 mm shorter. Massive synapophyses reprearise from
senting fused parapophyses and transverse processes
the pedicles and from the anterior half of the side of the centrum.

—

—

The zygapophyses, proportionately
series,

less robust than in the dorsal
diminish in size on successively more posterior sacrals. In

contrast to the orientation and spacing in the posterior dorsals,
sacral articular facets incline nearly parasagittally and are nar-

rowly spaced. At the last dorsal-first sacral articulation, the facets
are 5.5
apart, but between the third and fourth and fourth and
fifth sacrals they are only about 2
apart. At the fifth-sixth

mm

mm

sacral

3.5

The

the trend

reversed; the facets are spaced
apart and appear to be inclined at 10° from the vertical.
trend toward less verticality of facets is continued into the
articulation

is

mm

caudal

Sacral spines successively diminish in height and
anteroposterior breadth. The spine on the first sacral is approxiin height and 7
in breadth (versus 8.5
mately 8
height
and 8
breadth for the last dorsal spine). On the fifth sacral
series.

mm
mm

mm

mm

i


MASSETOGNATHUS POSTCRANIAL SKELETON

1970

mm

mm

same measurements are

7

5.5
and 4.2
respectively. This
continued into the caudal series. The apices of sacral
spines tend to be oval in contrast to those of the posterior dorsals
which are elongate and attentuated at each end.
Caudal centra decrease in length from 6.5
at the first caudal
to about 5
at the fifth. More posterior caudals preserved with
the

trend

is

mm

mm

MCZ

3691 are

disarticulated, and their position cannot be posiassigned. However, one isolated series of eleven caudals
shows a decrease in centrum length from 5
(which is evidence
that it is approximately the fifth caudal) at the first to 4
at
tively

mm

mm

the last (? fifteenth caudal). Other specimens

show

that at least the

caudals bear synapophyses. Articular facets are inclined
approximately 45°, at least through the first five caudals. The

width between the lateral edges of these facets decreases from
first five

at

6

mm

mm

(between the last sacral and first caudal) to 4.5
(between the fourth and fifth caudals). The terminal caudal

is

unknown.
Massetognathus pascuali probably possessed ribs on all presacral
vertebrae, as in other cynodonts for which adequate material is

known. Ribs were not found
cal vertebrae, although the

in association

with the

first six

cervi-

morphology of the transverse processes

and parapophyses on the axis through sixth cervical is clear evidence of their existence. These features cannot be verified at present on the atlas. The ribs of the seventh cervical
appear to have
been shorter than, but otherwise similar to, those of the anterior
dorsal series.

Dorsal ribs

in

Massetognathus pascuali are of basically two
and middle dorsal series, a freely articulating
form and proportions, and in the posterior

types: in the anterior
rib of normal costal

dorsal series, a fused rib with a Y-shaped distal end. Unfortunately, the transitional ribs between the two types are as yet

unknown.
The proximal ends of anterior and middle dorsal ribs are basically triangular. The tuberculum and capitulum form two corners
of the triangle; the shaft arises from the third
(Fig. 3A). On the
anterior aspect of this triangular surface is a slight crest (c.
Fig.
3A) comparable to a similar feature on the anterior dorsal ribs of

Cynognathus sp. (c. Fig. 3B. C). There is no other apparent feature that makes this type of rib distinctive. The maximum widths of

the shafts near their proximal ends are between 2.5 and 3 mm. The
distal ends, as preserved, are
this

basic

approximately 1.5

morphology (as opposed

to

the

mm

thick.

Ribs of

specialized posterior


BREVIORA

8

Figure
pasciiali

2.

in

The

posterior

dorsal

A, dorsal and B,

acetabular facet of the ilium; a

No. 352

and sacral region

lateral

views.

X

1.

in

Massetoguathus

Abbreviations:

a

il,

anterior process of rib shaft; b, ridge
on dorsal aspect of rib shaft; f a p, articular facet on anterior process of
rib shaft; gr, groove on dorsal margin of ischium; il, ilium; is, ischium;
p,

m

ischial tuberosity;
p, medial process on base of ilium for articulation
with ischium and pubis; p, parapophysis; p p, posterior process of rib shaft;
t, transverse process.
is t,

dorsal ribs to be described next) are associated with at least the
first thirteen dorsal vertebrae.

The following

description of the specialized posterior dorsal

based on the penultimate and last dorsal ribs preserved in
articulation (Fig. 2) and in addition, a few disarticulated pieces of
similar morphology. These ribs have a short shaft that bifurcates
into a Y-shaped terminus with two processes (ap, pp, Figs. 2, 4B).

The anterior process is broader than the posterior and bears, on
the dorsal surface of its tip, a rather flat, round facet (f a p, Figs.
2A, 4B). Articulating with this facet is the end of the posterior
process of the preceding rib. Presumably, the underside of the
ribs

is


MASSETOGNATHUS POSTCRANIAL SKELETON

970

3.
Proximal ends of dorsal ribs of A, Masseto^natliiis pascuali
and of B and C, Cynognatlms sp. (X V2) in anterior view. Abbreviations: c, crest on anterior aspect of shaft (see text for details).

Figure

(X

2),

posterior process also bears a facet. The rib as a whole projects
laterad from the vertebral column and appears not to have had
any
ventral curvature. In lateral view (Fig. 2B) the shaft and point of
bifurcation are at approximately the same level, but the anterior

and posterior processes incline somewhat ventrally. A low, bony

ridge (b. Figs. 2 A, 4B) runs obliquely onto the posterior process
from the point of bifurcation where it is most prominent. This
feature
sp.

is

comparable to a similar ridge on the ribs of Cynognatlms
4A) and other cynodonts; in the fourteenth thoracic

(b. Fig.

Figure

4.

cynodonts.

Specialized posterior dorsal
A. Cynognathus crateronotiis

History no. R. 2571), X V4.
Leavacliia duvenhagei (Rubidge
no.

92),

X

V2.

All

B,

Massetogucithiis

Collection,

dorsal views.

ribs

of

various

Museum

of

Natural

("lumbar")
(British

pascuali.

XL

C,

Graaf Reinet, South Africa,

Abbreviations:

a p,

anterior process

on dorsal aspect of rib shaft (of unknown function but
probably homologous in the forms shown here); f a p, articular facet on
anterior process of rib shaft; LI, L2, first and second lumbar vertebrae;
p p, posterior process of rib shaft; T14, T15, fourteenth and fifteenth
of rib; b, ridge

thoracic vertebrae.