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Full text of "Breviora"

HARVARD UNIVERSITY 

Library of the 

Museum of 

Comparative Zoology 



MUS. COMP. ZOOU. 

LIBRARY 



MAY 2 4 1977 
BREVIORA 

HARVARD 
UNIVERSITY 



MUSEUM OF COMPARATIVE ZOOLOGY 



Harvard University 



NUMBERS 410-436 
1973-1976 



CAMBRIDGE, MASSACHUSETTS, U.S.A. 

1977 



CONTENTS 

BREVIORA 

Museum of Comparative Zoology 

Numbers 410-436 

1973 

No. 410. The Color Pattern of Scmora michoacanensis (Duges) 
(Serpentes, Colubridae) and Its Bearing on the Origin 
of the Species. By Arthur C. Echternacht. 18 pp. 
September 20. 

No. 411. The Mandibular Dentition of Plagiomene (Dermop- 
tera, Plagiomenidae). By Kenneth D. Rose. 17 pp. 
December 28. 

No. 412. Mylostoma variabile Newberry, An Upper Devonian 
Durophagous Brachythoracid Arthrodire, with notes 
on related taxa. By William J. Hlavin and John R. 
Boreske, Jr. 12 pp. December 28. 

No. 413. The Chanares (Argentina) Triassic Reptile Fauna. XX. 
Summary. By Alfred Sherwood Romer. 20 pp. 
December 28. 

No. 414. Ecology, Selection and Systematics. By Nelson G. 
Hairston. 21 pp. December 28. 

No. 415. The Evolution of Behavior and the Role of Behavior 
in Evolution. By M. Moynihan. 29 pp. Decem- 
ber 28. 

No. 416. Museums and Biological Laboratories. By Ernst Mayr. 
7 pp. December 28. 

No. 417. A New Species of Cyrtodactylus (Geckonidae) From 
New Guinea With a Key to Species from the Island. 
By Walter C. Brown and Fred Parker. 7 pp. Decem- 
ber 28. 

No. 418. Morphogenesis, Vascularization and Phylogeny in 
Angiosperms. By G. Ledyard Stebbins. 19 pp. 
December 28. 



No. 419. Protopiychus, A Hystricomorphous Rodent from the 
Late Eocene of North America. By John H. Wahlert. 
14 pp. December 28. 

1974 

No. 420. Environmental Factors Controlling the Distribution of 
Recent Benthonic Foraminifera. By Gary O. G. 
Greiner. 35 pp. March 29. 

No. 421. A Case History in Retrograde Evolution: The Onca 
Lineage in Anoline Lizards. L A no/is amiectens 
new species. Intermediate Between the Genera Anolis 
and Tropidodactylus. By Ernest E. Williams. 21 pp. 
March 29. 

No. 422. South American Anolis: Three New Species Related 
to Anolis ni^rolineatus and A. dissimilis. By Ernest 
E. Williams. 15 pp. March 29. 

No. 423. A New Species of Primitive Anolis (Sauria Iguanidae) 
from the Sierra de Baoruco, Hispaniola. By Albert 
Schwartz. 19 pp. March 29. 

No. 424. The Larva of Sphindocis denticollis Fall and a New 
Subfamily of Ciidae (Coleoptera: Heteromera). By 
John F. Lawrence. 14 pp. June 28. 

No. 425. Systematics and Distribution of Ceratioid Anglerfishes 
of the Genus Lophodolos (Family Oneirodidae). By 
Theodore W. Pietsch. 19 pp. June 28. 

No. 426. Association of Ursus arctos and Arcfodus simus (Mam- 
malia: Ursidae) in the Late Pleistocene of Wyoming. 
By Bjorn Kurten and Elaine Anderson. 6 pp. Novem- 
ber 27. 

No. 427. The Stratigraphy of the Permian Wichita Redbeds of 
Texas. By Alfred Sherwood Romer. 31 pp. Novem- 
ber 27. 

No. 428. A Description of the Vertebral Column of Ervops Based 
on the Notes and Drawings of A. S. Romer. By 
James M. Moulton. 44 pp. November 27. 



No. 429. Anolis rupinae new species A Syntopic Sibling of A. 
inonticola Shreve. By Ernest E. Williams and T. 
Preston Webster. 22 pp. November 27. 

1975 

No. 430. Anolis marcanoi new species: Sibling to Anolis cyhotes: 
Description and Field Evidence. By Ernest E. Wil- 
liams. 9 pp. March 28. 

No. 431. An Electrophoretic Comparison of the Hispaniolan 
Lizards Anolis cyhotes and A. marcanoi. By T. 
Preston Webster. 8 pp. March 28. 

No. 432. Evolution and Classification of Placoderm Fishes. By 
Robert H. Denison. 24 pp. March 28. 

No. 433. South American Anolis: Anolis ihague. New Species 
of the Pentaprion Group from Columbia. By Ernest 
E. Williams. 10 pp. September 19. 

No. 434. South American Anolis: Anolis parilis. New Species, 
Near A. tuirus Williams. By Ernest E. Williams. 
8 pp. September 19. 

1976 

No. 435. Two New Species of Chelus (Testudines: Pleurodira) 
from the Late Tertiary of Northern South America. 
By Roger Conant Wood. 26 pp. April 8. 

No. 436. Stupendetuys geographicus. The World's Largest 
Turtle. By Roger Conant Wood. 31 pp. April 8. 



INDEX OF AUTHORS 

BREVIORA 

Museum of Comparative Zoology 

Numbers 410-436 

1973-1976 

No. 

Anderson, Elaine 426 

Boreske, JohnR., JR 412 

Brown, Walter C 417 

Denison, Robert H 432 

echternacht, arthur c 410 

Greiner, Gary O. G 420 

Hairston, Nelson G 414 

Hlavin, William J 412 

Kurten. Bjorn 426 

Lawrence, John F 424 

Mayr, Ernst 416 

MouLTON, James M 428 

Moynihan, M 415 

Parker, Fred 417 

PiETSCH, Theodore F 425 



ROMER, Alfred Sherwood 413, 427 

Rose, Kenneth D 411 

Schwartz, Alber r 423 

Stebbins, G. Ledyard 418 

Wahlert, John H 419 

Webster, T. Preston . ,. 429, 431 

Williams, ErnestE 421, 422, 429, 430, 433, 434 

Wood, Roger Conant 435, 436 



B R E V I O R A 

Miiseiiiii of Coiiipa]iliU&a^jv^^<2Blpgy 

LlBftARV 

us ISSN 0006-9698 ■'»^'^rfT 

Cambridge, Mass. September 20,w©|^2 4^^f^tPER 410 

THE COLOR PATT^^j^JW^'^O 

Sonora michoacanensis i^Dugis/S^TV 
(SERPENTES, GOLUBRIDAE) AND ITS BEARING 
ON THE ORIGIN OF THE SPEGIES 

Arthur C. Eghternaght 

Abstract. The extensive variation in color pattern of the 31 known 
specimens of Sonora michoacanensis is described and a model illustrating 
the relationships of the major components presented. Sonora aequalis 
Smith and Taylor is placed in the synonymy of Sonora michoacanensis 
muiabilis Stickel from which it differs only slightly in color pattern. It is 
suggested that S. michoacanensis evolved from a bicolor, banded ancestor 
within the 5. semiannulata group or from a common ancestor at the southern 
edge of the Mexican .Plateau following habitat shifts associated with 
climatic changes during the Pleistocene. Sonora michoacanensis is inter- 
preted as an imperfect Batesian mimic of elapid coral snakes (Micrurus 
sp.) , intermediate irl an evolutionary sequence beginning with the bicolor, 
banded ancestor and leading toward a more perfect, tricolor mimic. Known 
locality records of S. michoacanensis are mapped and selected meristic 
data presented in tabular form. 

Introdugtion 

The genus Sonora (Serpentes, Colubridae) is represented in 
Mexico, at the southern Hmit of its range, by Sonora micho- 
acanensis (Fig. 1). Sonora m. michoacanensis (Duges) is found 
in arid to semiarid habitats from the upper Balsas Basin in 
Puebla to the lower slopes of the Sierra de Coalcoman and 
southeastern Colima, whereas S. m. mutabilis Stickel occupies 
foothills of the Sierra Madre Occidental from southern Jahsco 
to Nayarit and Zacatecas (Duellman, 1961; Zweifel, 1956). 
The principal diagnostic difference between the subspecies is 
that S. m. michoacanensis has an unmarked tail, whereas the 
tail of 6*. m. mutabilis is banded. The two subspecies will be 
considered together in the discussion of color pattern to follow. 

The last review of this assemblage was by Stickel (1943). 



BREVIORA 



No. 410 



106 




Figure 1. Localities of documented specimens of Sonora iiiichoacanensis 
in Mexico. Hollow circles: 5. ?/?. michoacanensis; solid circles: S. m. muta- 
bilis. D. F. is the Distrito Federal. 



His clear and concise discussion included a detailed description 
of a single unusual specimen which Smith and Taylor ( 1 945 ) 
subsequently named, with no further description, Sonora 
aequalis. Stickel had been unwilling to base a new species on 
the single specimen because it was of unknown provenance and 
because it difTered from S. m. mutabilis only in color pattern, 
a character known to be highly variable in S. michoacanensis. 
Stickel presented data on all 18 specimens of S. michoacanensis 
(including ^S*. aequalis) then known but was able to examine 
only 1 1 of these. The holotype of S. m. ?nichoacanensis was lost, 
and he designated a neotype (Fig. 2), and described S. m. muta- 
bilis. The recent discovery of a specimen intermediate in color 
pattern to "typical" S. m. michoacanensis and S. aequalis and 
the availabihty of 14 specimens of S. ynichoacanensis collected 
over the 30 years since Stickel's paper ha\e made possible a 
re-examination of the variation in color pattern of the species 
and a reassessment of the taxonomic status of S. aequalis. Al- 



1973 



COLOR PATTERN OF SONORA 




Figure 2. Neotype of Sonora michoacanensis micfioacanensis, BMNH 1946. 
1.14.65. 



though this paper emphasizes color pattern, I have summarized 
meristic data for all known specimens (Tables 1 and 2) so that 
these data will be available to others. Counts of ventral scales 
were made according to the method of Dowling ( 1 95 1 ) and 
do not include the anal scale. Counts of subcaudal scales exclude 
the tip. For these reasons, data given here may differ slightly 
from those presented by Stickel (1943: 114-115). Where 
means are given for scale counts they are based only upon 
specimens that I was able to examine myself. The color de- 
scriptions are based on preserved specimens unless stated 
otherwise. 

Acknowledgements. William E. Duellman, Richard D. Estes, 
Ernest E. Williams and Richard G. Zweifel have all read the 
manuscript in its formative stages and I am grateful for their 
thoughtful criticism. The research was funded in part by a 
grant from the Boston University Graduate School (GRS BI- 
.15-BIO). I am indebted to the following individuals and 
institutions for the loan of specimens: William E. Duellman 
(University of Kansas Museum of Natural History, KU), Her- 
bert S. Harris (Personal Collection, RS-HSH), Hymen Marx 
(Field Museum of Natural History, FMNH), Hobart M. Smith 
and' Dorothy Smith (University of Illinois Museum of Natural 
History, UIMNH), David B. Wake (Museum of Vertebrate 
Zoology, MVZ), Charles F. Walker and Scott M. Moody (Uni- 
versity of Michigan Museum of Zoology, UMMZ), Ernest E. 
Williams (Museum of Comparative Zoology, MCZ) and Richard 
G. Zweifel (American Museum of Natural History, AMNH). 
Herbert S. Harris kindly provided a color slide of a living 
snake, and A. F. Stimson was instrumental in obtaining data 



4 BREVIORA No. 410 

on, and photographs of, the three specimens in the British 
Museum of Natural History (BMNH). Photographs of other 
specimens were prepared by Frederick W. Maynard. 

Variation of Color Pattern 

It is almost impossible to exaggerate the extent of variation 
in color pattern exhibited by the series of Sonora michoacanensis 
presently a\'ailable for study. Only the pattern of the head 
and neck seem relatively invariant. There is always a dark 
"mask" on an otherwise pale head. The mask may include the 
rostral and internasal scales, but typically begins between the 
rostral and a line connecting the anterior margins of the orbits. 
This dark area surrounds the eye and may extend forward on 
the side of the head to include all or parts of the nasal, loreal, 
preocular, anterior supralabials and those in contact with the 
orbit, the postorbitals and the temporals. Dorsally it covers 
the frontal, supraoculars and (often) parts of the prefrontals, 
terminating with a crescentic posterior margin on the parietals. 
There is a black or dark brown nuchal band (coUar) separated 
from the mask by a light-colored band. The nuchal band may 
completely encircle the body or may be interrupted midventrally. 
The anterior margin of the nuchal band is variable in shape 
but the posterior margin is usually straight across. The nuchal 
band is followed posteriorly by a light-colored band, usually 
three to fixt scales wide, which is, in turn, followed by another 
dark band. The last is a "half-saddle," its anterior margin 
straight across and its posterior margin crescentic. The half- 
saddle may completely encircle the body or be interrupted at 
the midline below. 

One specimen (FMNH 37141, Fig. 3A) has no pattern what- 
soever except that just described. All others have some dorsal 
banding pattern. This overall dorsal pattern ranges from one 
of only saddle-shaped triads consisting of a median gray band 
abutted fore and aft by black {e.g., AMNH 74951, Fig.'4B) to 
one of only broad black bands separated by a narrower gray 
band corresponding to the median gray band of the triads 
[e.g., KU 106286, Fig. 4C-4D). Individual snakes may have 
combinations of triads and broad black bands (Fig. SB, 3E-3F). 
Occasionally, the broad black bands are partially split by light 
pigment extending up from the venter {e.g., MVZ 76714, 
Fig. 3B). The light pigment (= ground color) may be ofT- 
white, gray, salmon or flesh-colored but to comply with Stickel's 



1973 



COLOR PATTERN OF SONORA 




Figure 3. Sonora michoacanensis michoacanensis: A. FMNH 37141, 
dorsal; B. MVZ 76714, dorsal; C. UMMZ 109904, dorsal; D. UMMZ 109904, 
ventral; E. FMNH 39129, dorsal; F. FMNH 39129, ventral. 



6 BRE\aORA No. 410 

(1943) terminolog)- it is referred to as red herein. The black 
bands mav not reach the ventral scutes but if thev do, thev mav 
or ma}- not extend across them to form rings. The same is true 
for the black elements of the triads which may not reach the 
\'entral scutes, may completely ring the body in such a way that 
the median gray band is also a ring, or may be joined along 
the midventral line so that the median gray band is incomplete. 
All three possibilities are seen on UMMZ 109904 (Fig, 3D). If 
a snake has both triads and broad black bands, it is usual for 
the triads to be found anteriorly and the black bands posteriorly 
[e.g., FMNH 39129, Fig. 3Ey. 

Taylor ( 1937) provides a description of color-in-life of Sonora 
michoacanensis michoacanensis from Guerrero and Jalisco. The 
ground color is red or pinkish, the dark elements of the triads 
black and the middle element of the triads yellow or gray- 
cream. A single specimen from Colima is similarly colored 
(Harris and Simmons, 1970), but Duellman (1961) described 
the middle element of the triads as white in a series of specimens 
from Michoacan. 

A specimen of Sonora michoacanensis michoacanensis collected 
in Jalisco by Percy CUfton (KU 106286, Fig. 4C-4D) is un- 
usual in that none of the black bands is split by red and there 
are no triads. None of the black bands except the nuchal and 
that immediately posterior to it reaches the ventral scutes. The 
broad black bands are expanded laterally just above the ventral 
scutes and some contact adjacent, similarly expanded bands. 
The black and gray bands (black and pale salmon in this 
specimen) are subequal in width. This pattern is approached 
in MVZ 76714 (Fig. 3B) but, prior to the discover\^ of KU 
106286, no S. michoacanensis were known with a pattern en- 
tirely of unsplit black bands alternating with gray bands of 
approximately equal width. In this respect, KU 106286 re- 
sembles Sonora aequalis (MCZ 6444, Fig. 4E-4F). 

In addition to presence or absence of caudal banding, Sonora 
michoacanensis michoacanensis and S. m. mutahilis differ in 
the number of gray bands of females, the number of complete 
triads of males, and the number of black bands unsplit by red 
of males and females. Sexual differences are e\'ident for all 
three of these characters in S. m. mutabilis, but not in S. m. 
michoacanensis (Tables 1 and 2). In addition, there is a sta- 
tistically significant (t = 3.91, P < .01 with 23 degrees of 
freedom) difTerence between the subspecies in total (left plus 
right) number of infralabials: The mean and standard devia- 



1973 



COLOR PATTERN OF SONORA 




Figure 4. 



Sonora michoacanensis mutabilis: A. UIMNH 18754, dorsal; 
B. 'AMNH 74951, dorsal; C. KU 106286, dorsal; D. KU 106286, ventral; 
E. MCZ 6444, dorsal; F. MCZ 6444. ventral. MCZ 6444 is the holotype of 
Sonora aequalis. 



8 BREVIORA No. 410 

tions for S. m. michoacanensis are 13.5 ± 1.09, for S. m. muta- 
bilis 12.1 ± 0.30. The number of infralabials is not sexuallv 
dimorphic for either subspecies. It is notable that of the seven 
S. m. michoacanensis with 13 fewer infralabials, three are from 
near Coalcoman, Michoacan (UMMZ 106604-6), where a 
single specimen (UMMZ 109904, Fig. 3C-3D) has one irregu- 
larly shaped caudal band, possibly indicati\-e of intergradation. 
Three other specimens with fewer than 14 infralabials (KU 
23791, MCZ 33650) or indications of low numbers of infra- 
labials (MVZ 45123) are from near Chilpancingo, Guerrero. 
The seventh such specimen is the missing holotype from 
"Michoacan" [Cope, 1884(1885)]. 

The Taxonomic Status of Sonora aequalis 

The only known specimen of Sonora aequalis (MCZ 6444)^ 
is recorded as being from Matagalpa, Nicaragua, but Stickel 
( 1 943 : 117) concluded that Matagalpa was most likely only 
the shipping point for material collected by W. B. Richardson. 
Other specimens in the same bottle as the snake and the locality 
label were two Eurneces lynxe lynxe (fide Joseph R. Bailey in 
Stickel, 1 943 : 1 1 8 ) , a lizard ^vhose range overlaps that of Sonora 
michoacanensis mutabilis. This and other evidence led Stickel 
to conclude that MCZ 6444 was found within or near the 
range of S. 7n. mutabilis. The pattern of MCZ 6444 consists 
of 26 black bnnds and 25 gray bands, the bands being all of ap- 
proximately the same width (the basis for the name aequalis). 
None of the black bands is split by red but se\'eral are xentrally 
concave (Fig. 4F). The nuchal band completely rings the body, 
but details in this region are obscure because of damage to the 
specimen. None of the black bands on the body reaches the 
venter and none is expanded laterally as in KU 106286. The 
cephah'c pattern is the same as that of S. michoacanensis and 
the tail is banded in triads as is characteristic of S. m. mutabilis. 
The specimen is badlv faded and no colors other than black 
and gray are apparent. 

In vie\'/ of the great \'ariation in dorsal body pattern evident 
within the su}:)species of Sonora michoacanensis, it does not 
seem to mc that the differences between S. aequalis and S. m. 

\Stickcl (1943: 117), in error, recorded tlu- snake as ;iii uiicatalogued 
specimen in the University of Michi,gan Museum of Zooloi^v. How and 
whv it got to Michigan and thence back to the Museum of Comparative 
Zoolog\' remains a mystery. 



1973 COLOR PATTERN OF SONORA 9 

mutabiUs are great enough to warrant taxonomic recognition 
of S. aequaUs. These differences are certainly no more startling 
than those of the almost patternless FMNH 37141 (Fig. 3A). 
KU 106286 (Fig. 4C-4D) seems to be a logical intermediate 
in pattern between S. m. mutabilis and S. aequalis. Extensive 
collecting in Mexico and Nicaragua over the last 30 years has 
brought to light no additional specimens of S. aequalis, but a 
number of additional specimens of "typical" (if that word is 
admissable) S. michoacanensis have been collected in Mexico. 
Of course, no additional specimens similar to FMNH 37141 
have been found either. 

It may be questioned whether it is any more justifiable to 
"sink" a species on the basis of one specimen (KU 106286) 
than it was to name one in the first place [S. aequalis, MCZ 
6444). But the discovery of KU 106286 has provided an im- 
portant link in what appears to be a continuum in pattern 
variation extending from the pattern (or, rather, lack of pat- 
tern) exhibited by FMNH 37141 to that of MCZ 6444 with the 
presence or absence of caudal banding superimposed. The 
possibility that KU 106286 is a hybrid of S. aequalis and S. m. 
mutabilis cannot be ruled out, but its likelihood is reduced by 
the absence of additional specimens of S. aequalis in collections 
made over the past 30 years. 

Relationships of the Components of Color Pattern 
AND THE Origin of Sonora michoacanensis 

Figure 5 illustrates my concept of the relationships of the 
various components of dorsal color pattern of Sonora michoa- 
canensis. Certainly no ontogenetic sequence is impHed, but the 
initial stages (Fig. 5A-5B) may be interpreted to suggest some- 
thing of the origin of the species. The ancestor of S. michoa- 
canensis may have been patterned verv^ much like MCZ 6444. 
Progressive erosion of the broad black bands (Figs. 5B-5D) 
would yield triads (Fig. 5E). A complex genetic mechanism 
would allow indi\ddual snakes to have various combinations of 
triads and unsplit black bands or triads in varying numbers and 
of varying distances apart. With the exception of the virtually 
patternless FMNH 37141, the most consistent element of color 
pattern is the gray band between adjacent unsplit black bands 
or as the median element in a triad (Stickel, 1943: 116). 

The banding pattern of MCZ 6444 is very similar to that of 
the banded forms belonging to the Sonora semiannulata group 



10 



BREVIORA 



No. 410 














Figure 5. Diagiammatic representation of color pattern variation of 
Sonora michoacanensis. The arrow spans one complete triad. Black r^ 
black, white :z= white or yellow, stippled rzz red. Upper figure of each 
pair, lateral view; lower figure, dorsal view. 



of southwestern United States and northern Mexico (Stickel, 
1938: 184-186; Stebbins, 1966). MCZ 6444 and all Sonora 
michoacanensis have 15 dorsal scale rows with no reduction as 
do some members of the S. semiannulata group. Sonora 
michoacanensis is distinguishable from members of the S. semi- 
annulata group in morphology of the hemipenis (Stickel, 1943: 
112), but the two groups are very similar in scutellation, teeth, 
dentigerous bone structure, microscopic scale striation and, 
generally, color pattern (Stickel, 1943: 110). It seems reason- 
able to assume that, as Stickel ( 1 943 : 118) seems to have 
suggested, S. michoacanensis had its origin within the S. semi- 
annulata group or that the two groups had a common ancestor. 
Members of the Sonora semiannulata group are presently 
found (Stebbins, 1966) in the southern Warm Temperate and 
Subtropical Climatic Zones as broadly mapped by Dorf (1959: 
198). These major climatic belts shifted southward \vith glacial 



1973 COLOR PATTERN OF SONORA 11 

advance during the Pleistocene (Dorf, 1959: 195) and the 
range of the S. semiannulata group or its ancestor may have 
been depressed southward into the area presently occupied by 
iS*. michoacanensis. Sonora michoacanensis may have differ- 
entiated as a relict at the southwestern fringe of the Mexican 
Plateau when climatic zones retreated northward with retraction 
of ^Visconsin glaciation. 

The Selective Significance of the Color Pattern 

OF Sonora michoacanensis 

A number of New World colubrid snakes have tricolor band- 
ing patterns which are reminiscent of the red, black and yellow 
or white patterns well known among the highly venomous coral 
snakes (Elapidae). Considerable circumstantial evidence has 
accumulated that the colubrids are mimics of those coral snakes 
with which they are sympatric and are thus avoided by those 
predators which have learned to avoid coral snakes (Dunn, 
1954; Hecht and Marien, 1956; but see Brattsrom, 1955). 
Three kinds of mimicry in snakes have been recognized ( Wickler, 
1968: 118). Batesian mimicry where the model is highly 
venomous and the mimic nonvenomous, Miillerian mimicry 
where both models and mimics are highly venomous and rein- 
force one another, and Mertensian mimicry where the model 
is highly \'enomous and the mimic mildly venomous. Sonora 
michoacanensis I?, a Batesian mimic of coral snakes of the genus 
Micrurus (Hecht and Marien, 1956: 345). 

The ranges of several species of Micrurus overlap or are con- 
tained within the range of Sonora michoacanensis (Roze, 1967). 
The basic color pattern of these elapids is one of black rings 
bordered on either side by narrower yellow or white rings, these 
triads being separated along the body by red. The order of the 
colors in the triads is, therefore, different from that of S. michoa- 
canensis. This difference is probably of little significance insofar 
as mimicry is concerned, as the distinction is difficult to make, 
even for a trained obser\'er, when the snakes are come upon 
suddenly or when they are moving. Potential predators pre- 
sumably have the same difficulty and Hecht and Marien (1956: 
339) present evidence that the order of the colors is less im- 
portant that the presence of the bright, contrasting colors 
themselves. In other words, the mimic need not be an exact 
renlica of the model to gain a selective advantage. 

The concept of Batesian mimicry requires that the mimic be 



12 BREVIORA No. 410 

less abundant than the model. If relative abundance in museum 
collections is an accurate reflection of relative abundance in 
nature, this requirement is met in that Micrurus is much 
better represented. It should, however, be noted that Sonora 
michoacanensis is a secretive species and may not be as rare 
as collections indicate. In a few areas where collecting has been 
repeated or intensive, small series have been obtained (see list 
of specimens ) . 

There are two alternative hypotheses concerning the origin 
of mimicry- : 1 ) The mimic evoh es in a single step by mutation 
(Goldschmidt, 1945), and 2) the mimic evolves gradually 
through selection of modifier genes improving upon an original 
mutant that had itself a shght selective advantage (Fisher, 1930; 
E. B. Ford, 1953). Sheppard (1959) strongly supports the 
second hypothesis and suggests that mimetic patterns are con- 
trolled by supergenes that have evolved stepwise. Recent experi- 
mental work by H. A. Ford (1971) supports the alternative of 
gradual evolution and pro\ides evidence that bird predators 
avoid a new partial mimic, strongly preferring a familiar non- 
mimetic form of prey. 

If my interpretation is correct, Sonora michoacanensis evolved 
from a bicolor, banded ancestor belonging to the S. semiannulata 
group. Although bicolor members of this group are sympatric 
with a coral snake {Micruroides euryxanthus) over much of 
their range, relative numbers of specimens in museums suggests 
the colubrid to be much the commoner snake. Thus, Batesian 
mimicry could not develop. To the south, however, the Pleisto- 
cene rehct population ancestral to S. michoacanensis may have 
been small relative to the populations of Micrurus with which 
thev evolved. If this was indeed the case, S. michoacanensis 
may as yet have not been perfected as a mimic and should be 
considered as intermediate in an evolutionary sequence leading 
from a nonmimetic, bicolor, banded ancestor toward a snake 
with a pattern of only triads. As there seems to be no geo- 
graphic trend in color pattern except the presence or absence 
of caudal bands and the generally better mimetic pattern of 
male S. m. mutabilis (see below), the gradual perfection of 
mimicry seems to be proceeding over the entire range of S. 
yyiichoacanensis. The extreme variability in color pattern evi- 
dent in the present population would result from lack of fixation 
at each of the major and minor gene loci responsible for pattern. 
This di\ersity of pattern would be tolerated because all of the 
intermediate types are to some degree mimetic except those that 



1973 COLOR PATTERN OF SONORA 13 

have bicolor banding patterns {e.g., MCZ 6444 and KU 
106286) or are nearly patternless {e.g., FMNH 37141). Such 
extremes are expected at low frequencies where inheritance is 
polygenic and where fixation has not occurred ( Strickberger, 
1968). The pattern of S. michoacanensis may be regarded as 
both protective in a mimetic sense and as concealing or dis- 
ruptive (Brattstrom, 1955). Hecht and Marien (1956: 346) 
have suggested that, "Banding may be an intermediate step 
through which a disruptive pattern is converted to a ringed, 
warning pattern, but functioning in both ways." It seems 
equally likely that the disruptive stage is intermediate to banded 
and tricolor, warning patterns. 

An interesting and unexplained observation is that male 
Sonora michoacanensis mutabilis are, by virtue of having more 
complete triads (Table 2), better mimics than females and 
than both sexes of S. m. michoacanensis. Among butterflies, 
mimetic patterns are often sex-limited to females, as are other, 
nonmimetic, polymorphisms (Sheppard, 1959: 137). E. B. 
Ford (1953) has attributed this phenomenon to the importance 
of visual stimuli in the courtship of butterflies. Females make 
a choice of mates largely on the basis of visual cues and Ford 
(1953: 68) reasons that a new color pattern in males might 
not stimulate a female to copulate. In moths, where olfactory 
courtship stimuli largely replace visual cues, both sexes may be 
polymorphic (Sheppard, 1959: 137). Noble (1937) reviewed 
the role of sense organs in the courtship of snakes and concluded 
that chemical and tactile senses play the primary^ roles in sex 
discrimination and courtship, respectively. Vision was found 
to be important only in that movement attracts snakes during 
the breeding season. Nothing at all is known of the behavior 
of S. michoacanensis, but it seems unlikely that the sexual 
dichromatism of S. m. mutabilis serves as an aid to sex dis- 
crimination or courtship. There are no clues as to why sexual 
dichromatism should be pronounced only in S. m. mutabilis 
and not in S. m. michoacanensis. 

The color pattern variation exhibited by Sonora michoa- 
canensis is at least equaled by that of Sonora aemula Cope of 
southern Sonora and Chihuahua, Mexico (Bogert and Oliver, 
1945: 374; Zweifel and Norris, 1955: 244; Nickerson and 
Heringhi, 1966: 136). Sonora aemula is rare in collections 
(Nickerson and Heringhi knew of only ten specimens), but it, 
like S. michoacanensis, is probably locally more abundant than 
collections indicate. Five of the known specimens were found 



14 BREVIORA No. 410 

in or near Alamos, Sonora. The species is sympatric with both 
Micruroides and Micrurus and one specimen {e.g., Arizona State 
University No. 6611; Nickerson and Heringhi, 1966, fig. 1) 
may ha\e typical MicruroidesAik^ triads (white-black-white), 
S. 7nichoacanensis-\ike triads (black-white-black), or expanded 
triads (black-white-black-white-black) like some Micrurus from 
southern Mexico and Guatemala. The area between the triads 
is red. Mimicry in S. aemula may be at the same stage of de- 
velopment as that which I have suggested for S. michoacenensis, 
as may mimicry in some species of the venustissimus and annu- 
latus groups of the genus S cap hiodonto phis in Central America 
(Taylor and Smith, 1943). Scaphiodontophis is a Batesian 
mimic of both Micrurus and the mildlv colubrid Erythrolarnprus 
(Hecht and Marien, 1956: 342). 

Known Specimens of Sonora michoacanensis 

The holotype of Contia michoacanensis Duges (Cope), 1884 
(1885) (= Sonora michoacanensis) has been lost, and Stickel 
(1943: 113) designated BMNH 1946.1.14.65 as neotype. 
BMNH specimens have been recatalogued since Stickel's (1943) 
paper and both old and new catalogue numbers appear in the 
listing to follow. Stickel ( 1943 : 115) examined an uncatalogued 
specimen of S. m. mutabilis in the American Museum of Natural 
History which was "tied with" (Stickel, 1943) AMNH 19714- 
19716, but the present whereabouts of this specimen is unknown 
(W. H. Stickel and R. G. Zweifel, personal communications). 
Zweifel (1956: 6) has questioned the locality data of all four 
specimens. They are said to haxe been collected in Distrito 
Federal, Mexico, but this is far remo\'ed from the range of the 
subspecies as presently understood from well-documented speci- 
mens (Fig. 1) and they are given as "Locality Unknown" 
below. Stickel ( 1 943 ) cited specimens in the collections of 
E. H. Taylor and H. M. Smith by field number. These speci- 
mens have all been deposited in museums, and both field 
numbers (preceded by "HMS") and museum catalogue num- 
bers are gi\en below. 

Sonora michoacanensis michoacanensis (18). COLIMA: 
Between Tecoman and Boca de Apiza, RS 596 HSH. 
GUERRERO: Chilpancingo Region, KET 23790-1, MCZ 
33650, MVZ 45123; 16 km^ S Taxco, UTMNH 25063 (HMS 
5440, holotype of Sonora erythrura Taylor, 1937); locality 
unknown, unnumbered specimen in the Museo Alfredo Duges, 



1973 COLOR PATTERN OF SONORA 15 

Colcgio del Estado Guanajuato. MICHOACAN: Apatzingan, 
FMNH 39128-9; Apatzingan, Hacienda California, FMNH 
37141; 3.2 km E Coalcoman, 1364 m, UMMZ 109904-6; 
12.2 km S Tzitzio, 1121 m, UMMZ 119457; 16 km S Uruapan, 
MVZ 76714; locality unknown, BMNH 1946.1.14.65 (formerly 
BMNH 1903.3.21, neotvpe), the holotype (presumed lost). 
PUEBLA: 10 km SE Matamoros, UIMNH 41688. 

Sonora michoacariensis rnutabilis (13). JALISCO: near 
Magdalena, FMNH 105296 (HMS 4659, paratype), FMNH 
105257 (HMS 4661, holotvpe), UIMNH 18754 (HMS 4660, 
paratvpe); 6.5 km S Tecalidan, MVZ 71356. NAYARIT: 
Jesus Maria, AMNH 74951. ZACATECAS: 8.8 km S Maya- 
hua, 1212 m, KU 106286; Mezquital de Oro, BMNH 1946.1. 
14.63 (formerly BMNH 92.10.31.42, paratype), BMNH 
1946.1.14.64 (formerly BMNH 91.10.31.43, paratype). LO- 
CALITY UNKNOWN: AMNH 19714-6 (paratypes), speci- 
men "tied with" AMNH 19714-6 (presumed lost), MCZ 6444 
(holotype of Sonora aequalis Smith and Taylor). 

Literature Cited 

BOGERT, C. M., AND J. A. OLIVER. 1945. A preliminary analysis of the 

herpetofaima of Sonora. Bull. American Mus. nat. Hist., 83: 297-426. 
Br.\ttstrom, B. H. 1955. The coral snake "mimic" problem and protec- 
tive coloration. Evolution, 9: 217-219. 
Cope, E. D. 1884(1885). Twelfth contribution to the herpetology of 

tropical America. Proc. American phil. Soc, 22: 167-194. 
DoRF, E. 1959. Climatic changes of the past and present. Contrib. Mus. 

Paleont. Univ. Michigan, 13: 181-210. 
Bowling, H. G. 1951. A proposed standard system of counting ventrals 

in snakes. British J. Herp., 1: 97-99. 
DuELLMAN, W. E. 1961. The amphibians and reptiles of ISIichoacan, 

Mexico. Univ. Kansas Publ., Mus. nat. Hist., 15: 1-148. 
DUNN^ E. R. 1954. The coral snake "mimic" problem in Panama. 

Evolution, 8: 97-102. 
Fisher, R. A. 1930. The Genetical Theory of Natural Selection. Oxford: 

Clarendon Press, xiv + 291 pp. 
Ford, E. B. 1953. The genetics of polymorphism in the Lepidoptera. 

Advance. Genet., 5: 43-87. 
Ford, H. A. 1971. The degiee of mimetic protection gained by new 

partial mimics. Heredity, 27: 227-236. 
GoLDSCHMiDT, R. B. 1945. Mimetic polymorphism, a controversial chapter 

of Darwinism. Quart. Rev. Biol., 20: 147-164, 205-250. 
Harris, H. S., and R. S. Simmons. 1970. A Sonora michoacanensis michoa- 

canensis (Duges) from Colima, Mexico. Bull. Maryland herp. Soc. 

6: 6-7. 



16 BREVIORA No. 410 

Hecht, M. K., and D. Marien. 1956. The coral snake mimic problem: 

A reinterpretation. J. Morph., 98: 335-365. 
NiCKERSON, M. A., AND H. L. Heringhi. 1966. Three noteworthy colubrids 

from southern Sonora, Mexico. Great Basin Nat., 26: 136-140. 
Noble, G. K. 1937. The sense organs involved in the courtship of Storeria, 
Tliamnophis and other snakes. Bull. American Mus, nat. Hist., 73: 

673-725. 
RozE. J. A. 1967. A checklist of the New World venomous coral snakes 
(Elapidac) , with description of new forms. American Mus. Novitatcs, 

No. 2287, 60 pp. 
Shei'pard, p. M. 1959. The evolution of mimicry; a problem in ecology 

and genetics. Cold Spring Harbor Symp. Quant. Biol., 24: 131-140. 
Smith. H. M., and E, H. Taylor. 1945. An annotated checklist and key 

to the snakes of Mexico. U. S. natl. Mus. Bull., No. 187, iv + 239 pp. 
Stebbins. R. C. 1966. A Field Guide to Western Reptiles and Amphibians. 

Boston: Houghton Mifflin Co., xiv + 279 pp. 
Stickel, W. H. 1938. The snakes of the genus Sonora in the United States 

and Lower California. Copeia, 1938: 182-190. 
. 1943. The Mexican snakes of the genera Sonora and 

Cliiouactis with notes on the status of other colubrid genera. Proc. 

biol. Soc. \Vashington, 56: 109-128. 
Strickberger. M. W. 1968. Genetics. New York: The Macmillan Co., 

X + 868 pp. 
Taylor. E. H. 1937. A new snake of the genus Sonora from Mexico, with 

comments on S. miclioacanensis. Herpetologica, 1: 69-73. 
, and H. M. Smith. 1943. A review of American sibynophine 

snakes, with a proposal of a new genus. Univ. Kansas Sci. Bull., 

29: 301-337. 
WiCKLER. "\V. 1968. Mimicry in Plants and Animals. New York: "World 

Univ. Lib., McGraw-Hill Book Co., 255 pp. 
ZwEiFEL, R. G. 1956. Additions to the herpctofauna of Nayarit, Mexico. 

American Mus. Novitates, No. 1953, 13 pp. 
, AND K. S. NoRRis. 1955. Contribution to the herpetology 

of Sonora, Mexico. American Midi. Nat., 54: 230-249, 

ADDED IN PROOF: Mr. Scott AL Moody has kindly called my attention 
to an additional specimen of Sonora michoacanensis miitahilis obtained too 
late for inchision in this study. The snake (UMMZ 131666) is typical of 
the subspecies and was found at Prcsa de El Molino. El Molino in Jalisco, 
Mexico. 



1973 



COLOR PATTERN OF SONORA 



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UWARY 

Museum of Comparative Zoology 
JAM? 1974 ^ 



HAftVARO 



us ISSN 0006-9698 



CambSB^?^ Number 411 

THE MANDIBULAR DENTITION OF 

PL A GIOMENE 
(DERMOPTERA, PLAGIOMENIDAE) 

Kenneth D. Rose^ 

Abstract. The peculiar bilobate lower incisors and the anterior lower 
premolars of the Early Eocene genus Plagiomene are described for the first 
time. Several groups of mammals have independently acquired incisors with 
divided crowns, but available evidence suggests that any resemblances to 
Plagiotnene, except in the case of Recent dermopterans, can be attributed to 
convergence. Nevertheless, the close resemblance between the incisors of 
Plagiomene and those of certain Recent elephant shrews (Macroscelididae) 
may be indicative of similar incisor function. The hypothesis that Recent 
dermopterans (Galeopithecidae) are descended from Plagiomene or a closely 
allied form (a view previously based primarily on molar morphology) is 
strengthened by the specimens described here. A brief review of fossil forms 
that have been referred to the Dermoptera is presented, and it is concluded 
that, at present, only two fossil genera, Plagiomene and Planetetherium, can 
with reasonable probability be assigned to the Dermoptera. 

Introduction 

The Early Eocene genus Plagiomene has been widely re- 
garded as an early member of the Dermoptera, a view based on 
the molar morphology, which is similar to that in living der- 
mopterans. Fossil evidence of dermopteran e\'olution is ex- 
tremely scarce. Although Plagiomene is better known than any 
other fossil forms that may be considered Dermoptera, it is 
represented only by dental and gnathic remains. Previous litera- 
ture on fossil dermopterans (known forms of which are all 
assigned to the family Plagiomenidae) is minimal, and has been 

^Department of Vertebrate Paleontology, Museum of Comparative Zoology, 
Harvard University. 



2 BREVIORA No. 411 

restricted to descriptions of parts of the dentition. None of the 
anterior dentition has been described or adequately figured be- 
fore, although the unusual incisors ha\'e been noted pre\'iously 
(Jepsen, 1962, 1970; Van Houten, 1945). The nearly complete 
lower dentition of Plagiomene described here (PU 14551, right 
mandible, and PU 14552, associated left mandible) is significant 
in pro\iding new e\idence that Plagiomene is related to and 
possibly ancestral to extant dermopterans. In addition, an in- 
complete right mandible, PU 13268, provides the first knowl- 
edge of the deciduous premolars in Plagiomene. 

Comparative material of Plagio?nene and other forms has 
been examined during this study. Abbreviations used in the 
text are as follows: 

AMNH American Museum of Natural Historv, New York 
MCZ Museum of Comparative Zoology (Mammalogy Col- 
lection), Harvard Uni\ersity, Cambridge, Massachusetts 
PU Princeton University Museum, Princeton, New Jersey 
YPM Peabodv Museum of Natural Historv, Yale Uni\er- 
sity. New Haven, Connecticut 

Description 

The lower dental formula of Plagiomene, 3.1.4.3, deduced by 
Matthew (1918) from f ragmentar\^ specimens, is confirmed bv 
PU nos. 14551 and 14552 (see Fig. 1 ). 

The three lower incisors (Figs. 1, 2, 4) of Plagiomene are 
semiprocumbent, with broad, bilobate crowns, of which the 
mesial lobe is the larger. Faint longitudinal depressions on the 
lingual sides of these larger lobes in Ii and U (see Fig. 1 lower) 
are potential sites for further digitation of the incisor crowns. The 
crowns are slighth- convex on the buccal surface and somewhat 
concave lingually. The incisors diminish in size from U to U, 
Ii being considerably larger than L,. They have an oval, mesio- 
distally compressed cross section at the root. In the absence of 
the crowns, Matthew (1918) inferred from the roots that the 
incisors were small and unspecialized. The specimens discussed 
here show this inference to have been incorrect. Expansion of 
the incisors (mostly mesiodistally) occurs at the base of the 
crowns and increases towards the tip. There are no cingula. A 
small wear facet on the labiodistal surface of the mesial lobe of 
left Ii suggests that upper incisors may have occluded with the 
lower incisors. This is of interest because in the Recent forms, in 



1973 



DENTITION OF Plagiomeue 







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BREVIORA 



No. 411 



■r 



>r 



Figure 2. Occlusal view of left mandibular dentition, PU 14552. 



1973 



DENTITION OF Plagiomeue 




' Figure 3. Occlusal view of right mandibular dentition, PU 14551. 



BREVIORA 



No. 411 




5/^tA 




Figure 4. Comparison of lower left incisors (I, at top) of Plagiomene 
(above) and Cynocephalus (below) . 



1973 



DENTITION OF Plagiomene 



TABLE I 

MEASUREMENTS (in mm) OF MANDIBULAR TEETH 

OF PLAGIOMENE 







PU 14552 


PU 13268 
(Deciduous teeth) 


Ix 


maximum mcsiodistal length 


2.3 






maximum height of crown 


3.4 






(measured Ungually) 






I2 


maximum mesiodistal length 


2.0 






maximum height of crown 


2.5 






(measured lingually) 






I3 


maximum mesiodistal length 


1.4 






maximum height of crown 


1.8 






(measured lingually) 






c 


maximum length 


2.0 






maximum breadth 


1.4 




Px 


maximum length 


1.7 






maximum breadth 


1.3 




P: 


maximum length 


2.8 


2.3 (dP,) 




maximum breadth 


2.0 


1.2 (dP,) 


P3 


maximum length 


3.7 


3.5 (dP3) 




maximum breadth 


2.3 


2.0 (dPa) 


P4 


maximum length 


4.3 


4.3 (dP,) 




maximum breadth, trigonid 


2.8 


1.9 (dP,) 




maximum breadth, talonid 


3.2 


2.3 (dP,) 


M, 


maximum length 


4.3 






maximum breadth, trigonid 


3.0 






maximum breadth, talonid 


3.5 




M. 


maximum length 


4.0 






maximum breadth, trigonid 


3.1a 






maximum breadth, talonid 


3.3a 




M3 


maximum length 


3.9 






maximum breadth, trigonid 


2.4 






maximum breadth, talonid 


2.4 





a,— approximate (tooth damaged) 



which P is lost and P is reduced, the anteriormost upper teeth 
have migrated distally, so that the lower, comblike incisors meet 
an edentulous area during centric occlusion. The most com- 
plete upper dentition known for Plagiomene, AMNH 15208 
(Szalay, 1969: 241), shows diminishing tooth size anteriorly, 
however, and does not preserve any incisors (except possibly 



8 BREVIORA No. 411 

P). This may indicate reduction or loss of the anterior upper 
teeth as in extant dermopterans. 

The single-rooted lower canine (Fig. 1) of Plagiomene is 
premolariform, consisting of a large anterior cusp, which rises 
above the crowns of the incisors and of Pi, and a prominent 
but low heel. A low, incipient cusp is observed on the anterior 
border. The canine is laterally compressed and its root is ellip- 
tical in cross section. 

The first premolar is a small, single-rooted tooth bearing one 
major cusp that may be followed by a much lower, small cusp- 
ule. Behind this is a still lower, incipient talonid cusp. 

P2 (Figs. 1-3), a much larger tooth than Pi, is double-rooted 
and "premolariform-semimolariform" (as defined by Szalay, 
1969: 199). The prominent protoconid is preceded by a dis- 
tinct though much smaller and lower paraconid, which is situ- 
ated directly anterior to the protoconid (not anterolingual to it, 
as in the teeth behind P2). The talonid is much broader and 
longer than in Pi, but still consists of only a single distinct cusp, 
homologous to the hypoconid. 

The third premolar is semimolariform. The protoconid is the 
largest cusp, and there is a conspicuous, lower paraconid an- 
terolingual to it. A less prominent metaconid de\'elops from 
the posterolingual border of the protoconid. Some individuals 
{e.g., YPM nos. 24966 and 24971) have a small, lower cuspule 
anterior to the paraconid. The trigonid is somewhat extended 
anteroposteriorly and there is no trigonid basin. The talonid 
is well de\'eloped, with both hypoconid and entoconid prom- 
inent, and with a rudimentary^ hypoconulid. The talonid basin 
is closed posteriorly but is open anteriorly in a deep buccolingual 
valley separating the trigonid and the talonid. This feature is 
more strongly expressed in the molariform teeth. 

P4 is fully molariform, differing from Mi chiefly in its slightly 
smaller size, but these two teeth are frequently almost indis- 
tinguishable. The three trigonid cusps and two main talonid 
cusps of P-i are large and sharp; the hypoconulid is lower and 
smaller. Some specimens {e.g., YPM 23578) have a small 
entoconulid anterior to the entoconid. 

The lower molars have been pre\'iously figured and described 
(Matthew, 1918), but a few features may be noted. M1-3 are 
very similar to each other. The trigonid cusps are high and 
sharp; the metaconid is usually as high as the protoconid or 
higher, and the paraconid is somewhat lower. In the talonid a 



1973 



DENTITION OF Pldgiomene 












5MM 



Figure 5. Right mandible with functional deciduous premolars (dPj.^) 
and unerupted jjemianent P2_4; Mj is in process of eruption. Lateral view 
of PU 13268. 



pronounced entoconulid is anterior to the entoconid on M2 and 
Ms, and it is present on Mi in some individuals. Posterior to the 
hypoconulid, the postcingulid rises in a broad cusphke projec- 
tion. This is well developed in Mi and M2 and, to a lesser ex- 
tent, in P4. In Ms the hypoconulid forms a small third lobe. 
Ms is usually narrower buccolingually than the other molars. 
The enamel of the molariform teeth is moderately crenulated, 
particularly in the talonid. A prominent ectocingulid is present 
on P3-M3 and posteriorly on P2. The posterior premolars and 
the molars clearly demonstrate a tendency toward polycuspida- 
tion, a characteristic of the Plagiomenidae. 

The deciduous premolars preserved in PU 13268, dP2-4 (see 
Figs. 5 and 6), are in general similar to their adult replace- 
ments. They possess the same cusps in approximately the same 
positions but are relatively longer anteroposteriorly and more 
cqmpressed buccolingually. The talonid of dP2 is more molari- 
form than in P2, exhibiting both a hypoconid and a small ento- 
conid. The talonid of dPs is similarly more expanded than that 
of the replacing tooth. In the trigonid of dPs the paraconid and 
metaconid are somewhat more distinct and better separated 
from the protoconid than in the permanent Ps. In dP4 as well, 
the talonid is elongated and expanded relative to its condition 
in P4, and the hypoconulid is much more pronounced, almost 
forming a small third lobe as in Ms. 



10 



BREVIORA 



No. 411 



Figure 6. Occlusal view of PU 13268. 



Discussion 

Incisor specializations comparable to those occurring in Pla* 
giomene are found in several other mammals. Incisors with 
digitate crowns have evolved independently in several unrelated 
groups, including Carnivora, Notoungulata, Macroscelidea, Der- 
moptera, and Insectivora. Among these, carnivores such as 
Canis and Ursus show tendencies toward digitation of the in- 
cisor crowns, but to a less marked degree than in Plagiomene, 
and there is surely no relationship involved. Patterson (1940) 
described the deciduous incisors of the notoungulate "Progaleo- 
pithecus" (^ Archaeophylus), so-named by Ameghino in refer- 
ence to the dermopteran-like, pectinate incisor crowns, but there 
is no reason to believe that Plagiomene is in anv wav related to 
the Notoungulata. 

Among the Insectivora, Nesophontes, a recently extinct Antil- 
lean form (McDowell, 1958: fig. 3), possesses bilobate incisors 
very similar to those in Plagiomene. Tenrec also shows a slight 
tendency toward digitation of the incisor crowns. There is little 
resemblance of the lower cheek teeth or the upper dentition of 
these forms to Plagiomene, however. The superficial similarities 
again may be attributed to convergence. 



1973 DENTITION OF Plagiomeue 11 

Certain Recent elephant shrews (Macroscelididae) bear a 
remarkable likeness to Plaoiomene in the conformation of the 
incisors; the most striking examples are Petrodromus and par- 
ticularly Rhynchocyon. In the former, the crowns of the per- 
manent incisors are bilobate, while the milk incisors {e.g., MCZ 
26113) may have three or four lobes. The lower incisors of 
Rhynchocyon are the closest to Plagiomene of any forms exam- 
ined. They are, however, all approximately of equal size in 
Rhynchocyon, in contrast to the decrease in size from Ii to Is in 
Plaoiomene. The remainder of the macroscelidid dentition is 



quite unlike that of Plagiomene. The most obvious contrasts 
are the loss of M3 (in the majority of known macrosceHdids, 
including both genera mentioned here) and the peculiar struc- 
ture of the molariform teeth (PI, MJ, M?.). Macroscelidids are 
not common in the fossil record, and of those known (Patterson, 
1965; Butler and Hopwood, 1957), none show any particular 
resemblance to Plagiomene. The family is unknown outside 
Africa. Therefore, the similar form of the incisors in some Recent 
macroscelidids is surely not indicative of any close relationship, 
although it may reflect functional similarities. 

Matthew (1918: 599) noted that the molars of the talpid 
Myogale [^= Desmana) were of somewhat similar structure to 
those of Plagiomene. Although he viewed this as "perhaps sig- 
nificant of a real though remote affinity" {ibid.: 600), the 
resemblances do not extend to the other teeth. It is unlikely 
that Plagiomene is related to talpids. 

Plagiomene has most frequently been compared with the 
living dermopterans, Galeopithecidae {e.g., Matthew, 1918; 
Romer, 1966; Szalay, 1969; Jepsen, 1970; among others), and 
alliance with this group still appears to be the most likely possi- 
bility. Matthew (1918) first suggested a relationship between 
the two groups after studying the molars of Plagiomene, which 
be described as "unlike any placental molars known to me 
except those of Galeopithecus" {ibid.: 601). Indeed, the mo- 
lariform teeth (P4-M3, as in Plagiomene) of extant dermopter- 
ans show many features in common with Plagiomene: prominent 
conules; absence of hypocone; paracone and metacone situated 
well lingual to the buccal margin; low paraconid; presence of 
an entoconuHd; talonid and trigonid separated by a deep bucco- 
lingual valley; and crenulated enamel. Furthermore, PJ and, 
to a lesser extent, P3 are molarized as in Plagiomene. Although 



12 BREVIORA No. 411 

the lower incisors of galeopithecids exhibit less resemblance to 
those of Plagiomene than do most of the forms discussed above, 
the long time inter\'al separating these two forms must be taken 
into account. It seems highly probable that the comblike in- 
cisors of galeopithecids must ultimately have been deri\'ed from 
incisors with divided crowns such as those present in Plagiomene 
(see Fig. 4). In fact, the form of I3 in extant dermopterans is 
an approximate morphologic intermediate between the form of 
the incisors in Plagiomene and the pectinate condition of Ii and 
I2 in the living forms. The dental formula of the Galeopitheci- 
dae differs from that of Plagiomene, in the loss of two ante- 
molar teeth ( probably Pi and P2 ) ; this is easily explained, 
however, for the reduction or loss of teeth is common in species 
that evolve enlarged, specialized teeth, such as the pectinate in- 
cisors of galeopithecids. In summary, the new evidence pro- 
vided by the anterior dentition of Plagiomene strengthens the 
view that it is in or near the ancestry of the Recent Dermoptera. 

This view, however, has been questioned recently. Van Valen 
(1967) regarded the Dermoptera as a suborder of the Insecti- 
vora. He suggested {ibid.: 271) that the Galeopithecidae may 
have been derived from Adapisoriculus (or an unknown related 
form) rather than from the Plagiomenidae, which he considered 
to be "unrelated to the Galeopithecidae" (although including 
both Plagiomenidae and Galeopithecidae in the same super- 
family of the Dermoptera, and placing Adapisoriculus in a 
suborder separate from the Dermoptera). 

From the preceding discussion, it is clear that incisors with 
di\ided crowns have arisen independently in many unrelated 
mammals and that such incisors function in various ways. Al- 
though incisors of different general morpholog)^ are included in 
this discussion, some of those mentioned above exhibit close 
resemblances to those of Plagiomene. Based on these similari- 
ties, incisor function in Plagiomeiie may have been close to that 
in Nesophontes, Petrodromus, and Rhynchocyon, and probably 
not so much like that in extant dermopterans. Unfortunately, 
little is known of incisor use in anv of these forms. Flvinsr lemurs 
are reported to use their comblike incisors "in scraping the 
green coloring out of leaves" (Gregory, 1951: 387, quoting 
H. C. Raven), in ingesting leaves (Winge, 1941), or in groom- 
ing (Wharton, 1950). They are strictly herbivorous, feeding 
mainly on leaves, but including shoots, buds, soft fruit, and 
coconut blossoms in their diet (Wharton, 1950; Walker et al., 



1973 DENTITION OF Plapiomeue 13 



&' 



1964; Medway, 1969). In contrast, macroscelidids are pri- 
marily insectivorous, feeding largely on ants (Brown, 1964), 
but almost nothing is known of how macroscelidids use their 
incisors. 

Hiiemae and Kay (1973) stress that incisors frequently func- 
tion in processes other than food ingestion and, in fact, that 
minimal use of incisors during ingestion in primitive mammals 
provided the opportunity to develop incisor specializations un- 
related to feeding. Therefore, it may not be correct to speculate 
that the diet of Plagiomene was similar to that of macroscelidids 
(indeed, differences in premolar and molar morphology would 
seem to be against siich a supposition) ; but it does seem likely 
that in both there are similarities of incisor function. 

Fossil forms that have been assigned to the Dermoptera are 
rare and are represented solely by jaws and teeth. Only two 
monotypic genera, Plagiomene (from the Early Eocene of Wyo- 
ming) and Planet ether ium} (from the latest Paleocene of Mon- 
tana), can with reasonable assurance be referred to the family 
Plagiomenidae, the only known family (in addition to the Re- 
cent Galeopithecidae) referred to the order. Planetetherium 
(Simpson, 1928, 1929; Szalay, 1969) is almost certainly the 
direct ancestor of Plagiomene. It is known from only one lo- 
cality, the Eagle Coal Mine at Bear Creek, Montana, where it 
occurs in carbonaceous shale just above the coal layer (Van 
Valen and Sloan, 1966). The site evidently represents an an- 
cient swamp, and many of the mammals present (including 
Planetetherium) were probably arboreal (Simpson, 1928; Van 

^Giasse (1955: 1727, fig. 1698) reproduced drawings of isolated incisors, 
from Simpson (1928: figs. 12 and 13) , and attributed the incisors to Planete- 
therium. This is apparently an unintentional error, which may have oc- 
curred because the description of the incisors (which Simpson, p. 14, stated 
"cannot be definitely classified or correlated with cheek teeth as yet") im- 
mediately followed the discussion of Planetetherium in Simpson's paper. 
Simpson believed that the incisors in question belonged to insectivores or 
primates, but he suggested no association with Planetetherium. The mor- 
phologies observed differ substantially, indicating that more than one taxon 
is involved. Inasmuch as Planetetherium is the most abundant form at Bear 
Creek, it seems not improbable that it is among the forms represented by 
the incisors. Szalay (1972: 25, figs. 1-9) has recently referred one of these 
incisors, AMNH 22153, to the primate Carpolestes, a common occurrence at 
Bear Creek. There is little evidence to confirm this allocation and, in fact, 
the morphology of AMNH 22153 may be closer to what might be expected in 
Planetetherium than in Carpolestes. 



14 BREVIORA No. 411 

Valen and Sloan, 1966; Jepsen, 1970). Planetetherium is by 
far the most commonly found member of the Bear Creek fauna. 
Se\'eral isolated teeth from the Early Eocene of France are 
the basis for a new genus and species being described by D. E. 
Russell, P. Louis, and D. E. Savage (in press) and regarded by 
them as a plagiomenid dermopteran. Casts of the teeth show 
features that suggest to me, however, that the new form may be 
neither a plagiomenid nor even a dermopteran. More complete 
evidence may in the future substantiate allocation of this form 
to the Plagiomenidae, but I do not believe that presently avail- 
able evidence is sufficiently convincing for such an assignment. 
L. S. Russell (1954) proposed Thylacaelurus montanus based 
on a maxillary fragment from the Kishenehn Formation (Late 
Eocene ?), British Columbia, which he believed to have mar- 
supial affinities. Although the specimen probably represents a 
placental (McKenna, in Van Valen, 1965: 394), Van Valen's 
(1967) allocation of the genus to the Plagiomenidae is unjusti- 
fied (see also Szalay, 1969: 242). Its relationships will remain 
obscure until further material is available. 

Van Valen (1967) referred the Mixodectidae to the Der- 
moptera. This move also seems unwarranted, but the resem- 
blance of Elpidophorus to the plagiomenids may be significant. 
This comparison is not new. Simpson (1936) first discussed this 
similarity and suggested that Elpidophorus pro\ided a suitable 
structural intermediate between the two families, but he rejected 
Elpidophorus as an ancestor of Planetetherium on the grounds 
that they were approximate contemporaries. This objection is 
no longer valid, howe\^er, for the range of Elpidophorus has 
since been extended back at least into Torrejonian time. Szalay 
(1969) reviewed the status of relationships between the Plagio- 
menidae and the Mixodectidae and concluded that a\'ailable 
evidence does not support such ties. Nevertheless, the cheek 
teeth (both upper and lower) of Elpidophorus are quite similar 
to those of Plaoiomene, sufficientlv close to susrsrest that more 
than con\'ergence may be involved. It is possible that Elpido- 
phorus lies in or near the ancestry of the Plagiomenidae (cf. 
Sloan, 1969: fig. 6). 

The Picrodontidae were placed in the Dermoptera by Romer 
(1966), but I concur with Szalay (1968: 32) that there is no 
evidence to support this. 

If the Plagiomenidae are truly related to the living fiying 
lemurs, as seems probable on the basis of dental e\idence pre- 



1973 DENTITION OF Plagiomeue 15 

sented above and by Matthew ^1918) and Szalay (1969), the 
Dermoptera have been distinct from other mammalian groups 
since at least Late Paleocene time. Recent dermopterans have 
acquired a peculiar suite of specializations (including in par- 
ticular the dental specializations and the patagium) which is not 
found in other mammals. In view of these considerations, recog- 
nition of ordinal status for the Dermoptera (as accepted by 
Simpson, 1945; Grasse, 1955; Butler, 1956; Walker, 1964; An- 
derson and Jones, 1967; among others) seems fully warranted. 

Acknowledgments 

I am indebted to G. L. Jepsen and V. J. Magho, Princeton 
University, for granting me the privilege of studying and de- 
scribing the Princeton specimens of Plagiomene. G. L. Jepsen 
also furnished me with drawings of the specimens prepared 
several years ago by R. Bruce Horsf all. 

Donald E. Savage kindly sent me a copy of a manuscript 
(Russell, Louis, and Savage, in press) describing a new form 
from the Eocene of France. Casts of the new specimens were 
generously provided by D. E. Russell. I am grateful to Russell, 
Louis, and Savage for graciously permitting me to include 
herein a dissenting view on the allocation of this new species. 

My appreciation is also extended to the following, who have 
given me access to specimens under their care: Mary Dawson, 
Carnegie Museum; Parish A. Jenkins, Jr., Department of Verte- 
brate Paleontology, Museum of Comparative Zoology; Malcolm 
McKenna, American Museum of Natural History; C. W. Mack, 
Department of Mammalog)^, Museum of Comparative Zoology; 
and Elwyn Simons, Peabody Museum of Natural History. 

Finally I would like to thank Thomas M. Bown, John G. 
Fleagle, F. A. Jenkins, Jr., G. L. Jepsen, and especially Br\an 
Patterson for critically reading the manuscript and offering help- 
ful suggestions and stimulating discussion. Laszlo Meszoly pre- 
pared the drawings; photographs are by A. H. Coleman. The 
illustrations were made possible through National Science Foun- 
dation Grant GB-30786 to A. W. Crompton. 

Literature Cited 

Anderson, S., and J. K. Jones, Jr. 1967. Recent Mammals of the World. 
New York: Ronald Press. 453 pp. 



16 BREVIORA No. 411 

Brown, J. C. 1964. Observations on the elephant shrews (Macroscelididae) 

of Equatorial Africa. Proc. zool. Soc. London, 143(1): 103-120. 
Butler. P. M. 1956. The skull of Ictops and the classification of the 

Insectivora. Proc. zool. Soc. London, 126(3): 453-481. 
Butler, P. M., and A. T. Hopwood. 1957. Insectivora and Chiroptera 

from the Miocene rocks of Kenya Colony. Fossil Mammals of Africa, 

no. 13. London: British Museum (Nat. Hist.) , 35 pp. 
Grasse, p. 1955. Ordre des Dermopteres. In Grasse, P. (ed.) , Traite de 

Zoologie. Paris: Masson, pp. 1713-1728. 
Gregory, W. K. 1951. Evolution Emerging. Vol. I. New York: Mac- 

millan. 736 pp. 

Hiiemae, K. M., and R. R, Kay. 1973. Evolutionary trends in the dynamics 
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Jepsen, G. L. 1962. Futures in retrospect. Yale Peabody Museum Report 
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. 1970. Bat origins and evolution. In "Wimsatt, W. A. (ed.) , 

Biology of Bats. Vol. L New York: Academic Press. 64 pp. 

Matthew, W. D. 1918. Part V — Insectivora (continued), Glires, Eden- 
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38: 565-657. 

McDowell, S. B., Jr. 1958. The Greater Antillean Insectivores. Bull. 
Amer. Mus. Nat. Hist., 115: 117-214. 

Medwav, L. 1969. The "Wild Mammals of Malaya. London: Oxford 

University Press. 127 pp. 
Patterson, B. 1940. The status of Progaleopithecus Ameghino. Field 

Museum Nat. Hist., Geol. Ser., 8(3) : 21-25. 
. 1965. The fossil elephant shreAvs (Familv Macroscelidi- 
dae) . Bull. Mus. Comp. Zool., 133 (6) : 297-336. 
RoMER, A. S. 1966. Vertebrate Paleontology. Chicago: Univ. of Chicago 

Press. 468 pp. 
RussrLL, D. E., P. Louis, and D. E. Savage, (in press) . Chiroptera and 

Dermoptera of the French Early Eocene. Univ. Calif. Publ. in Geol. Sci. 
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southeastern British Columbia. Ann. Rep. nat. Mus. Canada for 1952- 

1953, 132: 92-111. 
Simpson, G. G. 1928. A new mammalian fauna from the Fort Union of 

southern Mcmtana. Amer. Mus. Novitates, No. 297: 1-15. 
■ . 1929. A collection of Paleocene mammals from Bear 

Creek. Montana. Ann. Carnegie Mus., 19: 115-122. 
. 1936. A new fauna from the Fort Union of Montana. 



Amer. Mus. Novitates, No. 873: 1-27. 
. 1945. The principles of classification and a classification 



of mammals. Bull. .\nRi. Mus. nat. Hist. 85: 1-350. 



1973 DENTITION OF Plagiometie 17 

Sloan, R. E. 1969. Cretaceous and Palcocene terrestrial communities of 

western North America. Proc. North Amer. Paleont. Conv., part E: 

427-453. 
SzALAY, F. S. 1968. The Picrodontidae, a family of early Primates. y\mer. 

Mus. Novitates, No. 2329: 1-55. 
. 1969. Mixodectidae, Microsyopidae, and the insectivore- 

primate transition. Bull. Amer. Mus. nat. Hist., 140: 195-330. 
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(ed.) , The Functional and Evolutionary Biology of Primates. Chicago: 

Aldine, pp. 3-35. 
Van Houten, F. B. 1945. Review of latest Paleocene and early Eocene 

mammalian faunas. Journ. Paleo., 19(5): 421-461. 
Van Valen, L. 1965. Paroxyclaenidae, an extinct family of Eurasian 

mammals. Journ. Mammal., 46(3) : 388-397. 
. 1967. New Paleocene insectivores and insectivore classi- 
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Van Valen, L., and R. E. Sloan. 1966. The extinction of the multi- 

tuberculates. Syst. Zool., 15 (4) : 261-278. 
Walker, E. P., et al. 1964. Mammals of the World. Vol I. Baltimore: 

Johns Hopkins Press. 
Wharton, C. H. 1950. Notes on the life history of the flying lemur. 

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Winge, H. 1941. The Interrelationships of the Mammalian Genera. Vol. I, 

Copenhagen: C. A. Reitzels Forlag. (English translation.) 



B R E V I R A 

V 

iMu s^fftff^Tf Comparative Zoology 



J^ H^ t974 



US ISSN 0006-9698 



Cambridge, Mass. 28 December 1973 Number 412 

HARVARD 



um^m^c 



OMA VARIABILE NEWBERRY, 
AN UPPER DEVONIAN DUROPHAGOUS 
BRAGHYTHORAGID ARTHRODIRE, 
WITH NOTES ON RELATED TAXA 

William J. Hlavin^ 

and 
John R. Boreske, Jr.^ 

Abstract. All known gnathal elements of the durophagous aithrodire 
Mylostoma from the Late Devonian (Famennian) Cleveland Shale of Ohio 
show that the inferognathal and posterior palatopterygoid elements increase 
in size and maintain a constant shape during growth, Avhile the anterior 
palatopterygoids are paired elements in the juvenile condition which fuse 
into a single median gnathal in the adult. Dinognatlius is a synonym of 
Mylostoma. Mylosioma variahile, Mylostoma eurhinus, and Mylostoma new- 
berryi are here considered the only valid taxa. Mylostoma eastmani from 
the Grassy Creek Shale of Missouri (Famennian) is now considered a syno- 
nym of M. variahile; it was based on undiagnostic gnathal characters. The 
fusion of anterior gnathal elements is suggested as a possible origin of the 
median gnathal in the enigmatic arthrodire Biingartius and possibly also 
in the selenosteid Paramylostoma. 

Introduction 

, Newberry (1883: 146) described a left inferognathal from 
the Cleveland Shale member of the Ohio Shale Formation ( Late 
Devonian, Famennian) as Mylostoma variahile, referring to it as 
a "dipterine ganoid" on the basis of the similarity of its gnathal 
element to those of Dipterus and Ceratodus. In 1893, a concre- 
tion containing the virtually complete cranial, thoracic, and 

^Cleveland Museum of Natural History, Cleveland, Ohio, and Boston Uni- 
versity, Boston, Massachusetts. 

^Museum of Comparative Zoology, Harvard University, Cambridge, Mas- 
sachusetts. 



2 BREVIORA No. 412 

ventral shield of a single indi\'idual ^vas collected from the Cleve- 
land Shale exposures at Brooklyn, Ohio, and was obtained by 
the American Museum of Natural History, with the counterpart 
being acquired by the Museum of Comparati\'e Zoology. Dean 
( 1901 ) described both specimens as Mylostoma variabile, placing 
the taxon within the Arthrodira. Eastman (1906) reviewed the 
jaw mechanics of Mylostoma as well as the morphology of its 
gnathal elements and concluded that Mylostoma was an arthro- 
dire with a gnathal apparatus specialized for crushing. 

Hussakof (1909: 268) described Dinognathus ferox as "an 
imperfectly definable genus and species of arthrodire" on the 
basis of an isolated median gnathal. Eastman (1909) made a 
hypothetical reconstruction by placing the Dinognathus ferox 
t\pe of dentition over the inferognathals of Mylostoma terrelli 
and placing the posterior palatopter)'goids of M. terrelli on the 
labial side of the Dinognathus ferox median gnathal. Dunkle 
and Bungart (1945) described Dinognathus eurhinus, a second 
species of Dinognathus, on the basis of a median gnathal with 
general morphology differing from that of D. ferox, but with 
features giving evidence for a similar function. 

A recently discovered specimen (CMNH 8120) represents a 
complete set of jaw elements of an adult Mylostoma variabile. 
This specimen, along with other specimens in the Museum of 
Comparative Zoologv (MCZ), American Museum of Natural 
History ( AMNH),'bberlin College (OC), and the Cleveland 
Museum of Natural History (CMNH) has enabled this study 
of the morphology of the functional region of the inferognathals 
and palatopterygoids through various size-growth stages. Evi- 
dence of the fusion of the anterior palatopterygoids has been 
observed in the adult, aiding in the synonymy of mylostomatid 
taxa that were based oh undiagnostic character-states of the 
anterior palatopterygoids. 

Order Arthrodira 

Family Mylostomatidae 

Mylostoma variabile Newberry, 1883 

Mylostoma variabile Newberry, 1883: 146 
Mylostoma terrelli Newberry, 1883: 147 
Dinognathus ferox Hussakof, 1909: 268 
Mylostoma eastmani Branson, 1914: 62 

Holotype. OC 1 300, left inferognathal. 

Paratypes. MCZ 1435, left anterior palatopterygoid ; MCZ 



1973 MYLOSTOMA VARIABILE 3 

1436, right posterior palatoptcrygoid ; AMNH 42G, left anterior 
paIatopter)goid ; and AMNH 43G, right anterior palatopter)'- 
goid. 

Type locality and horizon. Sheffield Lake, Ohio. South Shore 
of Lake Erie, T 7 N, R 17 W, Lorain County, Ohio; Cleveland 
Shale member of the Ohio Shale Formation. 

Age. Famennian ( Late Devonian ) . 

Hypodigm. Cleveland Shale member of the Ohio Shale For- 
mation, Ohio: AMNH 7526, nearly complete disarticulated cra- 
nial and thoracic shields (counterpart = MCZ 1490) ; CMNH 
8129, left and right inferognathals, left and right posterior pala- 
topterygoids, median gnathal; AMNH 7915, 10701, CMNH 
6094, median gnathals; MCZ 1429-1431, CMNH 5080, 5150, 
5177, 6095, 6224, 7256, 7643, 7705, OC 1483, inferognathals; 
AMNH 44G, 3290, 3588, 3591, MCZ 1437-1438, 13271- 
13274, OC 1301, 1429, CMNH 5022, 5795, 7694, palatoptery- 
goids. Huron Shale member of the Ohio Shale Formation, 
Ohio: MCZ 13275, right inferognathal. Grassy Creek Shale 
Formation, Missouri: University of Missouri collections, median 
gnathal, posterior palatoptcrygoid. 

Revised diagnosis. Cranial shield having a wide lateral width 
and short anteroposterior length similar to that of the titanich- 
thyids. Postorbital element bordered posteriorly by paranuchal; 
centrals not in contact with marginals and are anteriorly sep- 
arated by pineal. Anterior palatopterygoids of juvenile fuse to 
form median gnathal in adult. Suborbitals narrow and long, 
orbits large. Median dorsal short without well-developed keel. 
Median gnathal of Mylostoma variabile possessing a greater 
width than length and less deeply excavated on either side of 
the longitudinal ridge than that of Mylostoma eurhinus. 

Systematic Discussion 

The holotype of Mylostoma variabile Newberry (1883: 146) 
is a left inferognathal, the size of which indicates that it belongs 
to a young adult of the species. The paratypes, comprising the 
anterior and posterior palatopterygoids, are characteristic of the 
known palatopterygoids of Mylosto?na. Dean (1901) described 
the most completely known specimen of M. variabile (MCZ 
1490, AMNH 7526). This specimen represents a young in- 
dividual of the species ( Plate 1 ) . All of the elements comprising 
the upper and lower jaw apparatus are well preserved and are 



4 BREVIORA No. 412 

the basis for Eastman's (1907) reconstruction of the mylosto- 
matid dentition. 

A second species, M. terrelli Newberry (1883: 147), repre- 
sents the left inferognathal (MCZ 1430) of an individual larger 
than the holotype of M. variabile. Hussakof (1909: 268) be- 
lieved the specific variations in this specimen could be attributed 
only to an age difference in M. variabile, and recommended that 
M. terrelli become a synonym of M. variabile. 

A third species of Mylostoma, M. newberryi Eastman (1907: 
224) is based on a pair of dental elements identified as the 
anterior portions of left and right inferognathals (OC 1302) and 
the posterior portion of a smaller left inferognathal (MCZ 1439) . 
These dental elements were originally described by Newberry 
(1889: 165) as belonging to M. variabile because of their dis- 
tinctive narrowness and triangularity, which he believed demon- 
strated diversity in the species. Earlier, Eastman (1906: 22; 
fig. E) figured these plates as pre-anterior palatopterygoids as 
part of his reconstruction of the upper dentition of M. variabile. 
This reconstruction is misleading since these pre-anterior pala- 
topterygoids are not present in the MCZ 1490 and AMNH 7526 
specimens. We believe that Eastman realized this a year later 
and established M. newberryi to include these "extra" plates. 
Morphologically, the dental plates represent the functional region 
of the inferognathal in a juvenile mylostomatid, having a very 
thin and narrow attachment with the blade of the inferognathal. 
This functionally weak attachment between the two areas in this 
bone may be a result of either an extremely early growth stage 
or a pathologic condition, the latter being here suggested as an 
explanation for the abnormal osteological conditions in the jaw 
elements of the dinichthyid Hussakofia ( Cossmann ) . 

Branson (1914) described Mylostoma eastmani on the basis of 
an isolated posterior palatopterygoid from the Famennian Grassy 
Creek Shale of Louisiana, Missouri. This specimen, along with 
an element referred to by him as an "occipital" (= nuchal) of 
Dinichthys rowleyi (correctly identified as a Dinognathus-\ike 
median gnathal by Dunkle and Bungart, 1945), comprises the 
only known occurrence of Mylostoma outside the Ohio Shale 
Formation. The character-states established by Branson (1914) 
for Mylostoma eastmani are undiagnostic since they do not differ 
from those of M. variabile, and we therefore include Mylostoma 
eastmani as a synonym of Mylostoma variabile. This occurrence, 
however, extends the distribution of this genus outside of the 
Appalachian Basin onto the mid-continent. 



1973 



MYLO STOMA VARIABILE 






/0^mm:\ 



••.'••-•;;5-i>-!'>.\ v';-,! '• -J'-;''-".-;;;.' • / 




Figure 1. Median gnathal elements (after Dunkle and Bungart, 1945) : 
A, Mylostoma (= Dinognathus) eurhinus CMNH 5063; B, Mylostoma varia- 
bile {= Dinognathus ferox) CMNH 6094; d = dorsal, v = ventral. 



6 BREVIORA No. 412 

Hussakof (1909: 268) described Dinognathus ferox (Fig. IB) 
from a single median gnathal (AMNH 7915) resembling the 
mvlostomatid dentition but ha\ins: uncertain affinities. Eastman 
(1909) felt that D. ferox represented the fused part of the an- 
terior palatopterygoids of an adult Mylostoma, but he lacked the 
appropriate specimens needed to prove this hypothesis. Dunkle 
and Bungart (1945), in describing Dinognathus eurhinus from 
a median gnathal (CMNH 5063; Fig. lA), did not advocate 
Eastman's ideas on fusion of the anterior palatopterygoids and 
opposed his hypothesis on anatomical grounds, which they felt 
were contradictory to the generalized pattern of jaw elements in 
all arthrodiran fish. They considered his reconstruction of the 
Dinognathus median gnathal as a dorsal gnathal element of 
Mylostoma to be invalid, arguing that the median gnathal could 
not have been derived from the fusion of the anterior pair of 
mylostomatid palatopterygoid elements. 

A recently discovered specimen (CMNH 8129; Plate 2) rep- 
resents a complete set of gnathal elements belonging to an adult 
M. variabile. This specimen consists of typical right and left 
inferognathals, right and left posterior palatopterygoids, and a 
Dinognathus ferox median gnathal. The discoxery of this speci- 
men, which lacks the anterior palatopterygoids but has posterior 
palatopterygoids and inferognathals associated with the D. ferox 
median gnathal element, confirms Eastman's hypothesis that the 
median gnathal of D. ferox represents the fusion of the anterior 
palatopterygoids in the adult mylostomatid (Fig. 2). A survey 
of all known existing mylostomatid palatal dental plates shows 
them to fall into three size categories : ( 1 ) the posterior pala- 
topterygoids, having a size-growth range from ju\^enile to adult, 
(2) the anterior palatopterygoids, all representing juvenile speci- 
mens of varying degrees but none approaching the adult size of 
their corresponding posterior palatopterygoids, and ( 3 ) the me- 
dian gnathals or fused anterior palatopterygoids, which all cor- 
respond to the adult size of the inferognathals and posterior pab.- 
topterygoids of the genus Mylostoma. 

In \iew of this evidence, it is su2:s:ested here that the taxonomv 
of the Mvlostomatidae ma\ be revised as follows: the 2:enus 
Dinognathus becomes a synonym of Mylostoina; Mylostoma 
variabile, the type species, includes also Dinognathus ferox, 
Mylostoma terrelli, and Mylostoma eastmani as synonyms; 
"Dinognathus'' eurhinus becomes a valid species of Mylostoma; 
Mylostoma newberryi, a species known only from the anterior 
portions of its inferognathals, is included within the M}losto- 



1973 



MYLOSTOMA VARIABILK 




A 




B 



Figure 2. A, Eastman's (1907) reconstruction of the upper jaw apparatus 
of Mylostoma variabUe, displaying the paired anterior palatopterygoids (AP) 
of the juvenile condition (reconstruction based on AMNH 42G-43G, 3591, 
and MCZ 1437) ; B, Reconstruction of the tipper jaw apparatus of Mylo- 
stoma variabile, displaying the median gnathal (MG) of the adult condition 
(fused anterior palatopterygoids; reconstruction based on CMNH 8129) ; 
PP = posterior palatopterygoids. 



8 BREVIORA No. 412 

matidae but its affinities with the other species of Alylostorna 
cannot be determined until additional material becomes avail-- 
able. 

Comparison With Other Arthrodires Having A 
Similar Jaw Apparatus 

As presently constituted, the family Mylostomatidae embraces 
the following genera: Mylostoma (= Dinognathus), Dinomylos- 
toma, and possibly Tafilalichthys. Eastman (1906) described 
Dinomylostoma, which is restricted to the medial Frasnian Shales 
of New York and Kentucky, as being phylogenetically the most 
primitive of the mylostomatids. Although incompletely known, 
it is morphologically and chronologically transitional between 
Dinichthys and Alylostoma. The inferognathal elements possess 
a flat, narrow oral surface, not yet expanded as in Mylostoma. 
The blade-length comprises approximately 45 percent of the 
inferognathal, displaying the generalized condition of the ad- 
ductor mandibulae muscles in the Frasnian mylostomatids, as 
compared to the 60 percent blade-length attained by the arched 
forward inferognathal elements of the Famennian Mylostoma. 
According to Dunkle and Bungart ( 1 943 ) , this specialized con- 
dition increases the length of the adductor mandibulae muscles 
to produce a more powerful bite. The anterior dorsal gnathal 
elements of Dinomylostoma display features transitional between 
the dinichthyid anterior supragnathals and the mylostomatid 
anterior palatopterygoids. The posterior gnathal elements, how- 
ever, have become completely specialized into well-defined my- 
lostomatid posterior palatopterygoids. This gnathal condition is 
paralleled to a less specialized degree by the Frasnian pholidosteid 
Malerosteus, described by Kulczycki (1957) from the Holy 
Cross Mountains of Poland. 

It is interesting to note that the enigmatic arthrodire Bungar- 
tius perissus Dunkle, which is known from a single complete 
adult specimen, lacks the anterior supragnathal element. The 
jaw elements preserved represent the corresponding right and 
left inferognathals, the posterior supragnathals, and a wtII- 
developed median gnathal. In this case, Dunkle (1947: 104) 
considered the "anterior supragnathal element either \estigial or 
completely absent." The absence of the anterior supragnathal 
elements in the adult Bungartius parallels the absence of these 
elements in the adult Mylostoma. The median gnathal is uniquely 
restricted to these two genera and we believe it has developed 



1973 MYLOSTOMA VARIABILE 9 

through the fusion of the anterior supragnathal elements during 
srrowth. This condition mav occur also in the selenosteid Para- 
mylostoma Dunkle and Bungart, in which the jaw mechanism is 
represented by an inferognathal specialized for crushing, and an 
associated posterior supragnathal. The anterior supragnathal 
and/or median gnathal is unknown in this genus. 

The gnathal condition, suggesting a durophagous habit, while 
not exclusively restricted to the Mylostomatidae as demonstrated 
by Bungartius, Paraniylostoma, and Malerosteus, has achieved 
its highest degree of specialization in the genus Mylostoma. This 
gnathal condition as manifested within other families of arthro- 
dires is believed to represent diverse attempts of broader adapta- 
tion and efficiency of the feeding mechanisms at the pachyosteo- 
morph le\el of organization as suggested by Miles (1969). 

On the basis of an isolated cranium, Lehman (1956) de- 
scribed Tafilalichthys lavocati as a new brachythoracid arthro- 
dire from the Famennian of Southern Morocco. Obruchev 
(1964), in his review of this genus, suggested that Tafilalichthys 
lavocati might be a mylostomatid, since the cranium is morpho- 
logically similar to that of Mylostoma as described by Dean 
(1901). No gnathal elements are yet known from T. lavocati, 
and therefore no positive assignment to the Mylostomatidae can 
be made at this time. However, the close relationship of the 
North American Famennian arthrodiran taxa to the Moroccan 
arthrodiran remains, as well as a review of the Cleveland Shale 
Arthrodira, will be of considerable interest in documenting the 
phylogenetic and paleozoogeographic relationships within the 
Mylostomatidae. 

The stratigraphic range of Mylostoma is relatively short, re- 
stricted to the Famennian (Late Devonian) time in North 
America. At this time the brachythoracid arthrodires achieved 
their highest level of adaptive radiation before extinction. 

ACKNOW^I.EDGMENTS 

Thanks are due to J. -P. Lehman and Daniel Goujet ( Museum 
National d'Histoire Naturelle, Paris), Farish A. Jenkins, Jr. 
and Robert H. Denison (Museum of Comparative Zoology), 
Richard Estes (Boston University), and William E. Scheele 
(Cleveland Museum of Natural History) for their helpful sug- 
gestions. This research was supported in part by grants from 
the Albion Foundation and Sigma Xi to Hlavin. 



10 BREVIORA No. 412 

Literature Cited 

Branson, E. 1914. The Devonian fishes of Missouri. Univ. Missouri Bull., 

15(31): 59-74. 
Dean, B. 1901. On the characters of Mylostoma Newberry. Mem. New 

York Acad. Sci., 2 (3) : 101-109. 
DuNKLE, D. 1947. A new genus and species of arthrodiran fish from the 

Upper Devonian Cleveland Shale. Cleveland Mus. Nat. Hist. Sci. Publ., 

8(10) : 103-117. 
, AND P. BuNGART. 1943. Comments on Diplognathus mirabilis 

Newberry. Cleveland Mus. Nat. Hist. Sci. Publ., 8 (7) : 73-84. 

AND . 1945. Preliminary notice of a remarkable 



arthrodiran gnathal plate. Cleveland Mus. Nat. Hist. Sci. Publ., 8 (9) : 

97-102. 
Eastman, C. 1906. Structure and relations of Mylostoma. Bull. Mus. Comp. 

Zool., 50(1).: 1-29. 
. 1907. Mylostomid dentition. Bull. Mus. Comp. Zool., 50 (7) : 

211-228. 

1909. Mylostomid palatal dental plates. Bull. Mus. Comp. 



Zool., 52 (14) : 261-269. 

HussAKOF, L. 1909. The systematic relationships of certain American 
arthrodires. Bull. Amer. Mus. Nat. Hist., 26: 263-272. 

KuLCZYCKi, J. 1957. Upper Devonian fishes from the Holy Cross Moun- 
tains (Poland) . Acta Pal. Polonica, 2 (4) : 285-380. 

Lehman, J.-P. 1956. Les arthrodires du Devonien Superieur du Tafilalet 
(Sud marocain) . Notes Mem. Serv. Geol. Maroc, 129: 1-70. 

Miles, R. 1969. Features of placoderm diversification and the evolution of 
the arthrodire feeding mechanism. Trans. Roy. Soc. Edinburgh, 68 (6) : 
123-170. 

Newberry, J. 1883. Some interesting remains of fossil fishes, recently dis- 
covered. Trans. New York Acad. Sci., 2: 144-147. 

. 1889. The Paleozoic fishes of North America. Monog. U.S. 

Geol. Surv., 16: 1-340. 

Obruchev, D. 1964. Class Placodermi. hi Osnovy Paleontologii 11. Mos- 
cow: Nauka, pp.1 68-260. 



1973 



MYLOSTOMA VARIABILE 



11 



'T" *^yf^»^ 




^_ — I 

ocrri 




B 



Plate 1. Mylostoma variabile (displaying cranial, thoracic, and ventral 
shields) , juvenile: A, MCZ 1490; B, counterpart AMNH 7526; SO = sub- 
orbital. 



12 



BREVIORA 



No. 412 



\ '»>;-'v >^' 



r"'^^*^ 



"|gi-v 







5cm 



Plate 2. Mylostoma variabile CMNH 8129; jaw elements of an adult 
showing left and right infeiognathals (IG) , left and right posterior pala- 
topterygoids (PP) , and a median gnathal = fused anterior palatopterygoids 
(MG) . 



S-/VA ^(a.>Mo 



B^HoJEoouV I O R A 

LIBRARY 

11 seiim^of ^Comparative Zoology 
JAM? 1974 ^ ^^ 



JAN 

US ISSN 0006-9698 




CAMBRiDGKajl^j^f^gl*^, December 1973 Number 413 



THE GHANARES (ARGENTINA) 

TRIASSIG REPTILE FAUNA 

XX. SUMMARY 

Alfred Sherwood Romer 

Abstract. A brief account is given of the geologic setting of the Tiiassic 
tetrapod faunas found in South America; the nature of the Chanares reptile 
fauna is summarized, and this fauna is compared with other Triassic as- 
semblages in South America and other continents. 

In nineteen pre\'ious papers in the Museum of Comparative 
Zoology Breviora^; an account has been published of the reptile 
fauna ifrom the Triassic Chafiares Formation of Argentina col- 
lected by the La Plata-Harvard expedition of 1964-65; this 
series includes, in addition to papers written by myself, contribu- 
tions by C. Barry Cox, Parish A. Jenkins, Jr., James A. Jensen, 
and Arnold D. Lewis. Except for a future detailed study of the 
skull of the cynodont Pro baino gnat hus by Edgar F. Allin and 
myself I have no further plans for publication on the Chafiares 
fauna. The present paper is intended to furnish a short summary 
of the results of the 1964-65 expedition. Except for a few forms 
recently described from the Chanares Formation, a recent paper 
by Bonaparte (1972) gives a succinct summary of all known 
reptiles from the South American Triassic, so that detailed ref- 
erences are unnecessary below. 

As noted in previous papers in this series, I am deeply in- 
debted to the National Science Foundation for grants for collec- 
tion, preparation, and publication of the Chanares fauna. 

Geologic Setting 
Until the last few decades, almost nothing was known of the 



^Breviora Nos. 247, 252, 264, 295, 333, 344, 352, 373, 377, 378, 379, 385, 389, 
390, 394, 395, 396, 401, and 407. 



2 BREVIORA No. 413 

Triassic tetrapod faunas of South America. Now, however, tetra- 
pods are known from fi\e discrete areas of Argentina and south- 
ern Brazil: 

( 1 ) The El Tranquilo Formation of Santa Cruz Province of 
Patagonia. From the upper part of this formation, ob\'iously of 
Late Triassic age, have been collected prosauropod dinosaur 
remains. These ha\'e been studied by Casamiquela, but the 
results have not been published; they appear to pertain to the 
European genus Plateosaiirus. 

(2) The Puesto Viejo Formation, in southern Mendoza Prov- 
ince. Undescribed fragmentary remains are present in the lower 
part of the formation; from the upper part, Bonaparte has 
described a primitive but somewhat specialized traversodontid 
gomphodont Pascualgnathus and, most interestingly, forms in- 
distinguishable from Cynognathiis and Kannemeyeria, the most 
characteristic genera of the Cynognathus zone of the Upper 
Beaufort beds of South Africa. The Scythian age of this forma- 
tion is obvious. 

(3) The Cacheuta Basin. In the precordillera west of Men- 
doza is a series of beds of Triassic age, the Cacheuta Series. I 
have elsewhere (Romer, 1960) given a brief resume of the 
geology. Four formations have long been recognized; in ascend- 
ing order they are the Las Cabras, Potrerillos, Cacheuta and Rio 
Blanco; recently a basal Rio Mendoza Formation has been dis- 
tinguished. Rusconi, in various publications (as Rusconi, 1951) 
has described \'ertebrates from these beds, including various 
fishes, many of uncertain systematic position, and from the 
Cacheuta Formation, flat-skulled amphibians of the genus Pel- 
orocephalus [Chigutisauriis], which, although comparable in 
many regards to the brachyopids of other Gondwana continents, 
appears not to pertain to that group. Reptilian remains are rare; 
in the older collections there was, apart from a few scraps, only 
the postcranial skeleton of a primiti\c thecodont, Cuyosuchus. 
More recently an indeterminate jaw from the Potrerillos Forma- 
tion has been described as Colbertosaurus, and Bonaparte has 
described the gomphodonts Andescynodon and Rusconiodon and 
a kannemeyeriid dicynodont, Vinceria from the Rio Mendoza 
Formation. Because the flora of the Cacheuta Series is of the 
Dicroidium type present in the Late Triassic, Stipanicic (1969) 
believes the Cacheuta beds to be relati\elv Late Triassic in as^e. 
Howe\er since the Dicroidhim flora extends well down toward 
the level of the Upper Beaufort beds of South Africa, Bona- 
parte's belief (1966, etc.) that part of the Cacheuta Series is 



1973 CHANARES SUMMARY 3 

relatively Early Triassic in age is reasonable. Unfortunately the 
reptile fauna is as yet too fragmentary in nature for adequate 
comparisons to be made. 

(4) Santa Maria Formation. From this Triassic formation in 
southern Brazil a few bones were early sent to the British Mu- 
seum; major collections were later made by and for Huene, 
whose full results were published in 1944; further collections 
have been made by Price and White for Harvard University, by 
Colbert for the American Museum, and by Price for the Bra- 
zilian Geological Survey. The Santa Maria Formation has been 
described by Beltrao ( 1 965 ) and by Bortoluzzi and Barbarena 
(1967). The vertebrate remains are confined to the upper part 
of the formation, and there is no known difference in the age 
of the beds between the three major collecting areas — near the 
city of Santa Maria, in the region of Chiniqua, west of that city, 
and in the Candelaria region, well to the east. 

The fauna is varied, but the nature of preservation is such that 
structural details are frequently obscure and many forms are 
imperfectly known. Included are the procolophonid cotylosaur 
Candelaria; the rhynchosaur Scaphonyx [Cephalonia] ; a number 
of thecodonts including Cerritosaurus, Rauisuchus, Prestosuchus, 
Hoplitosuchus, Procerosuchus; a fragmentary postcranial skeleton 
that appears to be a primitive saurischian, Staurikosaurus and a 
questionable second dinosaur, represented by a few vertebrae 
and limb bones; two carnivorous cynodonts, Chiniquodon and 
Belesodon; the gomphodont cynodonts Traversodon and Gom- 
phodontosuchus; the dicynodonts Barysoma, Dinodontosaurus 
and Stahleckeria. 

As discussed later, the Santa Maria Formation seems surely to 
be equivalent to the Los Rastros Formation of the Talampaya 
basin. 

(5) The Talampaya basin or Villa Union-Ischigiialasto 
cuenca. This is the largest and most richly fossiliferous of the 
bope-bearing South American Triassic areas. It lies on the 
boundary between La Rioja and San Juan provinces, between 
the Sierra de Safiogasta on the east and the Rios Bermejo and 
Guandacol on the west, and extends from the region of Villa 
Union on the north to the Sierra de Valle Fertil on the south. 
Faults are numerous, but in general the Triassic beds can be 
grouped in two areas, east and west of the flat alluvium-covered 
Talampaya plain, the two areas being essentially the two limbs 
of a major syncline, with various formations present in reverse 
order on the two sides of the plain. The area to the west of the 



4 BREVIORA No. 413 

plain is the better known and here the formations identified are 
much thicker than on the east. This region was explored by 
earlier geologists, but first adequately studied by Frenguelli 
( 1 946 ) ; his account has been modified and corrected by later 
workers, such as Groeber and Stipanicic (1953) and Ortiz 
(1968). To the northwest, in the region of Cerro Bolo there is 
an exceedingly thick series of beds that appear to extend con- 
tinuously upward from the Carboniferous "Paganzo I" to the 
Late Triassic; this region was studied by de la Mota, whose 
work, unfortunately, remains unpublished. To the southwest the 
series, as far as published results are concerned, terminates below 
in the presumed Triassic "Paganzo III." For much of the west- 
ern border this last is absent; if included, the major formations, 
in descending order, are : 

Los Colorados Formation, 

Lschigualasto Formation, 

Los Rastros Formation, 

Tarjados Formation (= Paganzo III). 

As described by Frenguelli, the Los Colorados beds were 
termed the Gualo Formation, a mistake corrected bv Groeber 
and Stipanicic. The lower part of the Los Rastros Formation 
was synonymized by Frenguelli with the Ischichuca Formation; 
as pointed out by Ortiz this is incorrect, for the type Ischichuca, 
in the Cerro Bolo region, is synonymous with the main carbon- 
bearing beds of the Los Rastros. The lowest redbeds were 
thought by Frenguelli to represent the Permian "Paganzo II,'' 
whereas, as Ortiz states, they are the redbeds of "Paganzo III," 
or Tarjados. 

Fragments of vertebrate skulls were reco\'ered by Frenguelli 
from the Ischisfualasto Formation and described bv Cabrera in 
1943. The richness of fossils in this formation was disclosed by 
the Har\'ard-Buenos Aires Museum expedition of 1958 (Romer, 
1966). For many years, from 1958 on, the lschigualasto beds 
were worked by expeditions from the Instituto Lillos of Tucu- 
man, at first under O. A. Reig, later with great success by J. F. 
Bonaparte. The rich reptile fauna includes the rhynchosaur 
S ca phony x: the thecodonts Proterochampsa, Saurosuchus, Ven- 
aticosuchus, Triassolestes, Aetosauroides and Argentinosuchus ; 
the rare saurischian dinosaurs Herrerasaurus and {?)Ischisaurus; 
the ornithischian Pisanosaurus ; fragmentan- remains perhaps 
representing the carnivorous cynodont Chiniquodon; the gom- 
phodonts Exaeretodon, Proexaeretodon and Ischignathus; the 



1973 CHANARES SUMMARY 5 

dicynodont Ischigualastia. Except for representatives of Ischi- 
gualasto forms in transitional beds, no reptiles are known from 
the Los Rastros beds or the underlying Tarjados Formation. 
Abo\e the Ischigualasto Valley rise the high clifTs of the Los 
Colorados. Except for a single dicynodont, Jachaleria, the faunal 
content of most of the thick series of Los Colorados redbeds is 
unknown; from the few meters available at the summit of the 
cliffs Bonaparte has described (1972b) a fauna of very late 
Triassic age, including the thecodonts Riojasuchus, Pseudhes- 
perosuchus and N eoaetosauroides ; the primitive crocodilian 
H emiprotosuchus ; the prosauropod Riojasaurus; and fragmen- 
tary materials comparable to Tritylodon. 

We are here concerned mainly with beds lying to the eastern 
side of the basin, which was little studied by earlier workers; 
Jensen and I (1966) have discussed the geology here. Most of 
the formations present can be matched with those on the west 
side of the \alley, although they appear to be much thinner here. 
The formations present (all adequately represented along the 
course of the Arroyo de Agua Escondida) are, in descending 
crder : 

-Los Colorados Formation, 

Ischigualasto Formation, 

Los Rastros Formation, 

Chafiares Formation, 

Tarjados Formation, 

Talampaya Formation. 

These formations are presumably underlain by the Carboni- 
ferous and Permian beds of "Paganzo F' and "Paganzo II," 
which are exposed on the slopes of the Safiogasta Range, east of 
a major north-south fault at the western margin of the moun- 
tains; in the area studied, however, we have not seen a contact 
between "Panganzo II" and the base of the Talampaya beds. 
The latter formation is best exposed in the clifTs forming the 
walls of the "Puerta de Talampaya," where 180-200 meters of 
these beds are present. They mainly consist of soft sandstones, 
but with occasional "cobbles." No fossils of anv sort have been 
found. They appear to be purely continental in nature and are 
not improbably Early Triassic in age, or possibly Late Permian. 

Unconformably above the Talampaya beds are the hard sand- 
stones of the Tarjados Formation, some 385 meters in thickness 
at the i\rroyo de Agua Escondida. These beds correspond, ap- 
parently, to part or all of the sandstones elsewhere termed 



6 BREVIORA No. 413 

"Panganzo III." For the most part they are red, but in the 
southern part of the area studied the upper beds are white in 
color. Fossils are rare, but a few fragmentary dicynodont re- 
mains have been found in the upper layers. They are presumably 
Early Triassic in age. 

On the irregular upper surface of the Tar j ados sandstones 
lie unconformably the 75 meters of the volcanic ash deposits 
constituting the Chaiiares Formation. The uppermost layer of 
the Tar j ados, about half a meter thick, forms an uneven, undu- 
lating surface of hard resistant materials suggesting hydrothermal 
action. Obviously there was major volcanic activity in the region 
at that time. The Chaiiares sediments show none of the laver- 
ing that would be expected if the ash had been laid down in 
water; presumably there was merely a covering of the then 
existing surface with tremendous quantities of volcanic ash in 
Pompeii-like fashion. Bearing out such a conclusion is the fact 
that no trace of water-dwelling amphibians or fishes have been 
discovered in the Chaiiares and — more significant — almost 
all the numerous reptile remains found are in the lowest few 
meters of the ash deposits. Apparently the ash falls resulted in 
the local extermination of the vertebrate fauna. 

As Jensen and I noted in 1966, it is not customary' in Argen- 
tina to give a formation name to a set of beds of such limited 
thickness. I believe, however, that it is warranted in this case 
because of the distinctive nature of the sediments, and most 
especially, because of the vertebrate fauna contained in them. 
Bonaparte (1967) suggested that the Chaiiares beds are 
equivalent to those of the Ischichuca Formation, the type section 
of which lies in the Cerro Bola region. However, both Ortiz 
(1968) and I (1971) have shown that this is incorrect. Bona- 
parte informs me that light-colored beds, which may be compa- 
rable to those of the Chaiiares, are present below the typical Los 
Rastros in the southwestern part of the basin, and that he has 
collected reptiles of Chafiares type there. I have not \'isited this 
area. Ortiz includes these beds in the Los Rastros Formation, 
and if one does not wish to distinguish a separate Chafiares 
Formation, one might include it in the Los Rastros — despite 
the marked contrast in the nature of the sediments — but could 
not, of course, consider these beds as part of the so-called 
"Ischichuca." 

Conformably above the Chafiares ash beds are the Los Rastros 
sediments of shales, clays, and sandstones, with intercalated 
carbonaceous layers, similar in nature to the beds of this forma- 



1973 CHANARES SUMMARY 7 

tion in the western part of the basin. Because of numerous 
faults it is impossible to determine the thickness of the Los 
Rastros in this region, but it is obviously much less than the 
estimated 600 meters found west of the Ischigualasto Valley. 

Only a limited exposure of Ischigualasto Formation sediments 
is present in this region; the thickness observed is but 175 
meters, as compared with 400-500 meters in the type area. 
Abo\'e the Ischigualasto Formation are present Los Colorados 
beds, only 95 meters thick; whether this is the total amount 
originally deposited or whether they were originally thicker and 
later reduced by erosion before deposition of overlying Tertiary 
sediments is uncertain. 

The Chanares Fauna 

Below are listed the reptiles discovered in the 1964-65 expedi- 
tion and described in earlier papers in this series. A few forms 
are represented by fairly complete specimens; others are known 
only from fragmentary materials. Much further collecting is 
possible; one may hope that if and when such collecting can be 
done, much better material of many of the forms already de- 
scribed may be obtained and additions be made to the faunal 
list: 

Dicynodonts : 

Chanaria platyceps 
Dinodontosaurus brevirostris 
Dinodontosaurus platygnathus 
Kannemeyeriid indet. 

Gomphodont cynodonts: 
Massetognathus pascuali 
Massetognathus teruggii 
Alassetognathus major 
Megagomphodon oligodens 

, Carnivorous cvnodonts: 
Probelesodon lervisi 
Probelesodon minor 
Probainognathus jenseni 

Thecodonts : 

Luperosuchus fractus 
Lagerpeton chanarensis 
Lagosuchus talampayensis 
Lagosuchus lilloensis 
Chanaresuchus bonapartei 



8 BREVIORA No. 413 

Gualosuchus reioi 
Gracilisuchus siipanicicorum 
Lewimchus admixtus 

Dicynodonts. In contrast to the wealth of dicynodonts in the 
later Permian, the group in the typical Triassic deposits is re- 
stricted to a few forms of relatixely large size (their place as 
herbivores appears to ha\e been taken oxer mainly by rhyncho- 
saurs and gomphodonts). In the Chanares beds such forms are 
present, but only in modest numbers, dicynodont specimens 
constituting but perhaps 5 percent or so of the total of reptiles 
collected. A few postcranial remains suggest the presence of a 
kannemeyeriid ; apart from this, three types of dicynodonts are 
present, all of which are assigned by Cox to the characteristically 
Middle Triassic family Stahleckeriidae — Chanaria platyceps, 
Dinodontosaurus platygnathus, and D. brevirostris. Chanaria is 
a form not present elsewhere; howe\er, the Dinodontosaurus 
species are quite similar to the genotypic form from the Santa 
Maria Formation ( presumably of somewhat later age ) . 

As also mentioned below, ecologic factors tend to separate 
stratigraphically and topographically the three common herbi- 
vore groups — dicynodonts, gomphodonts and rh) nchosaurs — 
of the South American Middle Triassic fossiliferous areas. In 
the Santa Maria beds, dicynodonts and rhynchosaurs are, so to 
speak, "allergic" to one another; rhynchosaurs abound in the 
deposits near Santa Maria city but are unknown in the two 
other major fossil beds in this formation where dicynodonts are 
abundant. At Ischigualasto all known dicynodonts ha\e been 
found in a stratigraphically narrow band, about half-way up the 
formation, and quite distinct from higher levels where gompho- 
donts abound, and frotn lower levels where rhynchosaurs are 
plentiful. Ill the Chanares beds, as noted abo\e, almost all 
fossils are from the lowest part of the formation, but 1 ha\e the 
impression that all dicynodonts collected were from the \ery 
base, within a meter or two of the unconformity with the 
Tarjados sandstones, whereas other types tended to occur up to 
a dozen or so meters higher. 

Gomphodonts. Gomphodont cynodonts arc the dominant 
herbivores in the Chanares beds; more than half of all specimens 
collected in the 1964-65 expedition were members of this group. 
Nearly all clearly pertain to a single genus, Massetognathus. In 
the first box of fossils received in Cambridge, Massachusetts, 
there was present a considerable series of specimens that seemed 
to sort out clearly into two size groups, and hence I descril^ed 



1973 CHANARES SUMMARY 9 

them as belonging to two species, M. pascuali and M. teruggii. 
As I noted later, the full collection, when received, broke down 
such a clear distinction. Dr. James Hopson tells me that in 
primitive African cynodonts which he has been studying, a very 
considerable size range is to be found; this suggests that M. 
pascuali and M. teruggii merely represent populations of two 
sizes of the same species. However, as my tables show, the size 
distribution is heavily weighted above the peak that one may 
reasonably believe to represent mature adults, and the presence 
of two common species of Massetognathus is still a not unreason- 
able assumption. Still further, the size range of specimens that 
seem to belong to this genus is such that I find it impossible to 
believe that the amount of growth necessary to reach the size of 
the largest specimen can have been possible if a single species 
(or even two species) had been present, and hence have with 
some confidence given the name Massetognathus major to this 
relatively enormous skull. 

Nearly all the gomphodonts in the collection appear to be 
reasonably assignable to a single genus. However, two rather 
large individuals are clearly distinctive, and I have given the 
name Alegagomphodon oligodens to this rare form. 

The Chafiares gomphodonts are clearly members of the family 
Traversodontidae, a group to which all known South American 
gomphodonts belong ( and also forms present in the Manda beds 
of East Africa). In the Santa Maria beds of Brazil gomphodonts 
are less common, and are represented mainly by the genus 
Traversodon. This genus may well have descended from Mas- 
setognathus, but its remains are too poor to allow a detailed com- 
parison. The Ischigualasto traversodontids are obviously much 
more ad\'anced types. 

Rhynchosaurs. Quite as significant as the presence of certain 
forms in a given formation is the absence of expected types. 
Most Triassic reptile faunas, except those of the very earliest and 
very latest parts of the period, are notable for the presence of 
rhynchosaurs, often in great abundance. In our Chafiares col- 
lections there is not the slightest trace of a rhynchosaur ( despite 
the fact that identifiable elements of this type of animal, most 
especially upper tooth plates, are readily preserved and readily 
recognized ) . 

Why are no rhynchosaurs present? It is not because they had 
not yet evohed, for although the Chafiares beds date from a 
fairly early time in the Triassic, primitive rhynchosaurs were 
already present in the Cynognathus Zone, definitely earlier, and 



10 BREVIORA No. 413 

were abundant in the Manda beds of East Africa, which (as 
discussed later) are probably somewhat earlier than the Chaiiares 
Formation. Quite certainly rhvnchosaurs had evolved bv the 
time of formation of the Chaiiares beds and (although there is 
no proof) may have been present in Argentina at that time. 

Their absence here is quite surely, as I have suggested else- 
where (Romer, 1973), attributable to some ecologic factor. 
Rhynchosaurs and gomphodonts, in South American deposits at 
least, seem to be basically incompatible.^ In the Ischigualasto 
beds, rhvnchosaurs are exceedingly abundant in the lov/er part 
of the formation, but in our 1964-65 expedition we found no 
specimens in the upper half of the beds. On the other hand, on 
our expedition we found gomphodonts to be very rare in the 
lower part of the Ischigualasto Formation but very abundant in 
the upper half of these deposits. Rather surely the contrast is 
related to the type of plants present; the rhynchosaurs fed on 
some type of plants having a hard-shelled "seed" for which the 
"cracking" dentition of these forms was a necessity; the gompho- 
donts, as the grinding character of their teeth and the absence 
of a cracking device indicate, fed upon some different types of 
plant materials. In the Santa Maria Formation, gomphodonts 
are not as conspicuous as in the Ischigualasto and Chanares 
beds, but such gomphodonts as are present there are absent in 
the beds near Santa Maria city where rhynchosaurs alone are 
present. If, as is probable, rhynchosaurs were present in South 
AmxCrica in Chanares times, they would presumably have been 
of a relatively primitive type, comparable to Stenaulorhynchus of 
the Manda beds rather than the more advanced genus present 
at Santa Maria and Ischigualasto. 

Carnivorous cynodonts. In the Permian and earliest Triassic 
the typical carnivores are therapsids; during the Triassic car- 
ni\orous therapsids are reduced and disappear, to be replaced by 
archosaurs (but giving rise to the earliest mammals before dis- 
appearing completely). In the Chaiiares beds, thecodont archo- 
saurs were becoming abundant, but carni\orous cynodonts were 
still present and modestly abundant. They are interesting in 
being more ad\'anced than Thrinaxodon and Galesaurus of the 
earliest Triassic and without the somewhat specialized features 
seen in Cynognathus, the common form in the Late Beaufort of 
South Africa. Probelesodon lewisi is quite clearly ancestral to 

'Charig tells mc, however, that there is no evidence for this in the Manda 
beds of East Africa. 



1973 CHANARES SUMMARY 11 

Belesodon of the somewhat later Santa Maria beds; apparently 
two species are present, P. lewisi, fairly common, and a smaller 
form, Probelesodon yninor. More interesting is Probainognathus, 
in which a starthng advance is the presence of a socket — a 
glenoid cavity - — in the squamosal for attachment of the jaw. 
This, however, is only a half-way stage in the development of the 
mammalian system of jaw suspension, for this glenoid is for the 
reception of an articular body of the lower jaw formed by a 
fusion of the posterior elements of the reptilian jaw type; the 
dentary bone, which in mammals articulates with the squamosal, 
is as yet not quite in touch with the squamosal. The teeth of 
Probainognathus are usually worn and show only the main 
fore-and-aft row of cusps present in the teeth of primitive mam- 
mals and seem to lack the row of basal "cusplets" found in early 
mammals. For this reason it was thought for a time that Pro- 
bainognathus could not be on the direct line of ascent to mam- 
mals. However, Hopson has studied a little-worn dentition in 
which these cusps are present and hence it may be reasonably 
considered to be a true pre-mammal, or at least very close to the 
actual ancestral line. 

Thecodonts. Although carnivorous cynodonts still survived, 
thecodonts were well on their way toward succeeding them as 
dominant carnivores. In earlier years we knew little of this group 
except for a few primitive forms in the Early Triassic and ( apart 
from the specialized phytosaurs) only a few survivors in the 
Late Triassic, where the thecodonts were already being succeeded 
by the dinosaurs descended from them. One could have rea- 
sonably assumed that were Middle Triassic beds well known, 
the thecodonts would be discovered to be a varied group, with a 
variety of forms leading in different directions — toward ptero- 
saurs, bird ancestors, crocodilians and dinosaurs. Our increased 
knowledge of Middle Triassic fossil deposits in recent decades 
has gone far toward verifying this assumption, for although 
many phyletic lines are far from clear, it is obvious that during 
the middle part of the Triassic the thecodonts were undergoing 
a rapid radiation into a wide diversity of types. The only large 
Chaiiares form is Luperosuchus, represented only by an incom- 
plete skull, which appears to be a member of the prestosuchid 
(or rauisuchid) assemblage, of uncertain relationship. No close 
affinities are known for Lewisuchus or the two small long-legged 
types, Lagosuchus and Lagerpeton, represented mainly by hind 
legs. Chanaresuchus and Gualosuchus are long-snouted, prob- 
ably amphibious forms related to Cerritosaurus of the Santa 



12 BREVIORA No. 413 

Maria and Proterochampsa of Ischigualasto; once suggested as 
crocodilian ancestors, the proterochampsids do not seem to be 
related to that group, but are not impossibly related to the 
phytosaur pedigree. A progressive form is Gracilisuchus, related, 
it would appear, to Ornithosuchus of the later Triassic, which 
has suggestive resemblances to primitive theropods, although it 
is far from certain that the ornithosuchids are ancestral to these 
dinosaurs. The Chanares thecodonts, as was stated, increase con- 
siderably our knowledge of thecodont diversity, but as vet do 
little toward establishment of any major archosaur evolutionary 
lines. 

Comparison With Other Faunas 

As knowledge of Middle Triassic faunas has increased, ideas 
as to the stratigraphic position and interrelations of these faunas 
ha\e been expressed by a variety of workers, such as Bonaparte, 
Colbert, Cox, Reig, and myself. I shall here merely consider the 
interrelationships of these faunas from the point of view of the 
Chanares assemblage. I have recently re\iewed the Triassic 
faunas in a plenary paper (1972) for the Second Gondwana 
Symposium, and hence full documentation here seems unneces- 
sary. 

As I pointed out some years ago (1966) Triassic faunas may 
be roughly divided into three successive groups, (A) early, 
(B) intermediate, and (C) late, although it is obvious that 
such distinctions cannot be completely clear-cut, and transitional 
assemblages may be expected. A-type faunas have long been 
known from the Upper Beaufort beds of South Africa, contain- 
ing mainly therapsids, although with early members of other 
groups, notably thecodonts. C-type faunas are almost ubiquitous, 
being known from redbeds Late Triassic deposits in Eiuope, 
North America, South Africa, China, and (now) South Amer- 
ica. In such faunas dinosaurs are already prominent, and their 
thecodont predecessors are still present, whereas therapsids are 
practically extinct (although the earliest mammals descended 
from them have now appeared ) . 

As to B-type faunas, these were until recently almost entirely 
unknown, since deposits of Middle Triassic age in the northern 
continents are mainly marine, and in South Africa the Molteno 
beds, of Middle Triassic age, appear to be nearly barren of 
fossils (although footprints are abundant). What should one 
have expected in B-type faunas? Ob\'iously, a transition between 



1973 CHANARES SUMMARY 13 

A and C, with a gradual reduction of therapsids and an increase 
in archosaurs, including a variety of thecodonts and the begin- 
nings of the dinosaurs. The B-type faunas now known from the 
southern continents do show these expected transitional features. 
But, in addition, they show positive characteristics of their own, 
in the great flourishing of gomphodont cynodonts and rhyncho- 
saurs - — groups that had their beginnings in the A-type faunas of 
the Early Triassic but seemed of little importance. 

Let us first consider the South American situation. A-type 
faunas are certainly present in the Puesto Viejo Formation and 
not improbably in the Cacheuta series, as Bonaparte believes 
(although the evidence is still scanty). The C-type is present 
both in the upper part of the Los Colorados Formation, as now 
being developed by Bonaparte, and in the El Tranquilo Forma- 
tion. Between, we have in Argentina the succession Chanares- 
Los Rastros-Ischigualasto, three formations that lie conformably 
one above the other in the Talampaya basin. The Los Rastros 
beds are almost barren of fossils, but it is, I think, generally 
agreed that the Santa Maria Formation of Brazil is equivalent, 
and thus, for vertebrates, our sequence may read Chafiares-Santa 
Maria-Ischigualasto. All three clearly include B-type reptile 
faunas. ^ 

The Chaiiares beds, earliest of the three, clearly are an early 
part of the B complex. The gomphodonts are members of the 
traversodontid family, and the diademodontids and trirachodon- 
tid types present in the Scythian Cynognathus beds of South 
Africa appear to be extinct. The carnivorous cynodonts are of 
relatively ad\anced types — rather more advanced than Cyno- 
gnathus. Rhynchosaurs are absent, but this, as noted above, ap- 
pears to be due to some ecological factor, since primitive rhynch- 
osaurs were already present in the A-type Cynognathus zone. 
And, while few thecodonts were present in the Cynognathus 
zone, thev are here alreadv varied in nature and in some cases at 
least, of a progressive type. 

The Santa Maria beds are quite surely later in age than the 
Chafiares beds but, just as the presumably equivalent Los Ras- 
tros beds lie in the break above the Chaiiares, the fauna of the 
Santa Maria beds follows that of the Chafiares with some ad- 
vances but without any major change. Among the dicynodonts, 
Dinodontosaurus continues Httle changed into the Santa Maria. 
Of gomphodonts, the Santa Maria Traversodon, although poorly 
known, may well be descended with litde change from Mas- 
setognathus. The Santa Maria carnivorous cynodont Belesodon 



14 BREVIORA No. 413 

appears to be but an enlarged edition of Probelesodon of the 
Chanares. In both Chanares and Santa Maria beds, most of the 
thecodonts are imperfectly known, but it is very probable that, 
given more adequate material, several close comparisons may 
come to be made, and Cerritosaurus of Santa Maria is very 
similar structurally to Chanaresuchus of the earlier formation. 
As Cox (1968) states, "the Chafiares fauna is only slightly 
earlier than that of the Santa Maria." The only advance of any 
note is that here (as might be expected) we have the first sign 
of the evolution of dinosaurs from thecodonts in Staurikosaurus 
Colbert and possibly the fragmentary materials described by 
Huene as Spondylosoma. 

Next above the Los Rastros Formation, without disconformity, 
lies the Ischigualasto Formation, from which a very considerable 
fauna is now known. The only dicynodont, Ischigualastia, is a 
large form of no particular stratigraphic significance. Gompho- 
donts of several genera — Exaeretodon, Proexaeretodon, Ischig- 
nathus — are exceedingly abundant, especially in the upper part 
of the formation. All are traversodonts that are more advanced 
than those of the Chanares and Santa Maria beds. Carnivorous 
cynodonts are rare and represented only by fragmentary remains 
that ha\e been referred to the Santa Maria genus Chiniquodon. 
Thecodonts are, again, fairly common and \'aried. Saurosuchus 
is a relative of Luperosuchus of the Chanares but of larger size; 
Proterochampsa is similarly a large member of the Chanare- 
suchus-Cerritosaurus group. Triassolestes, originally thought to 
be a dinosaur, is probably a thecodont, but perhaps a crocodi- 
loid relative. Interesting is the presence of Aetosauroides, first 
representative of a thecodont type that was to continue, ap- 
parently little changed, to Late Triassic times. Of dinosaurs we 
now have (although as rarities) the probable saurischians Her- 
rerasaurus and Ischisaurus and, most interestingly, the oldest 
known ornithischian, Pisanosaurus. Despite advances, we have 
a close tie with the Santa Maria in that the common Ischigua- 
lasto rhynchosaur Scaphonyx (thoroughly studied in an unpub- 
lished thesis by Sill) is almost indistinguishable from the species 
present in the Santa Maria. Chatterjee (1969) has suggested 
that the Santa Maria localities containing Scaphonyx are later 
than those containing the remainder of the fauna. But there is 
no geological e\idence to support this suggestion; all the verte- 
brate fossils, rhynchosaurs, dicynodonts and others, appear to 
come from the relatively thin upper portion of the Santa Maria 
Formation. In sum, the fauna of the Ischigualasto Formation 



1973 CHANARES SUMMARY 15 

is ad\'anced over that of the Santa Maria, but the difference is 
not great, as Bonaparte has noted. 

We lack any means of correlation of these South American 
beds with the standard marine series, but since these faunas are 
ob\'iously post-Scythian and pre-Norian, it is natural to suggest 
a one-to-one correlation of Chanares-Santa Maria-Ischia^ualsto 
with Anisian-Ladinian-Carnian. I have in the past expressed 
doubts as to whether the horizon of the Ischigualasto Formation 
was as high as the Carnian. In the European Keuper reptile 
remains are known only from the upper, Norian, part of the 
sequence and we have no knowledge of the reptile fauna of 
Carnian times. Further, in the Ischigualasto Valley the Los 
Colorados redbeds tower for some 400-500 meters above the 
top of the Ischigualasto beds and, except for a single dicynodont, 
our knowledge of the Los Colorados fauna is derived from the 
vcv)^ topmost beds of this formation, so that it is possible that the 
lower part of these beds are of Carnian age. However, consid- 
eration of the faunas found in India and the northern continents 
(discussed below) suggests that our B-type faunas continued into 
Carnian days. It is thus very likely that the age of our B-type 
Middle Triassic faunas conflicts with the classic division of the 
Triassic into lower, middle and upper. Stratigraphically the 
Middle Triassic includes Anisian and Ladinian, while the Upper 
Triassic includes Carnian, Norian and Rhaetic ; as regards verte- 
brates it is probable that the Middle Triassic includes Carnian 
and Anisian and Ladinian as well, with the "upper" C-type 
faunas restricted to the Norian and Rhaetic. 

If one wishes to compare the Chaiiares and other South Amer- 
ican B-type faunas with those of other continents, one naturally 
turns first to South Africa, since current theories of continental 
drift suggest that in the Triassic South America and Africa were 
closely apposed to one another. If this was the case one would 
expect similarities between the faunas of the two continents. But 
even if the South Atlantic were then nonexistant, there would 
remain a considerable distance between the Talampaya basin, 
and even the Santa Maria region, and the fossiliferous beds of 
east and south Africa. One should expect that there might be a 
considerable difference between the reptile faunas of these regions 
just as there is today a very considerable difference between the 
reptile faunas of, for example, California and the Atlantic coast 
areas of North America. 

The African beds concerned are ( 1 ) the Molteno beds of the 



16 BREVIORA No. 413 

Stormberg Series cf South Africa, (2) the Ntawere beds of 
Zambia, and (3) the east African Manda beds. 

The Molteno beds are quite surely Middle Triassic in age and 
should contain a fauna of the B-type. But while footprints are 
tantalizingly abundant, actual fossils are rare, and such few as 
ha\'e been described are of uncertain stratigraphic position and 
may either come from the top of the Cynognathus zone (as in 
the case of a cynognathid) or from the base of the redbeds (as 
in the case of a traxersodont gomphodont ) . 

The Ntawere beds are as yet not fully explored and as yet little 
material has been described [cj. Cox, 1969). Two zones appear 
to be present. The lower, in which Diademodon is present, may 
well be equivalent to the upper part of the Cynognathus zone, 
with an A-type fauna. The upper zone fauna includes two 
dicynodonts — the stahleckeriid ^ambiasaurus and the kanne- 
meyeriid Sangusaurus, two traversodont cynodonts, Luangwa 
and a second form as yet undescribed, and fragments of theco- 
dont«;. In default of fuller data, the age of this fauna is difficult 
to determine. The presence of traversodonts suggests the B-type; 
but tra\ersodonts occur at an Early Triassic age in Argentina 
and may well ha\ e been as early in appearance in Africa. 

Of especial interest is the Manda Formation of east Africa, 
from which a very considerable fauna is known, owing to col- 
lections made for Huene, by Parrington, and by an English ex- 
pedition a decade ago. Unfortunately much of the known ma- 
terial is undescribed or described in only preliminary fashion. 
I am indebted to A. J. Charig for the faunal list given here. 
There are three dicynodonts, Kannemeyeria, Tetragonias, and a 
third undescribed form. No carnivorous cynodonts are as yet 
described, but gomphodonts are numerous and \aried, including 
the diademodontids Theropsodon and {?)Aleodon, the triracho- 
dontid Cricodon and a \arietv of traversodontids of which the 
only remains as yet described are assigned to four species of the 
Q:enus Scalenodon. Some seven thecodonts have received names, 
including the prestosuchids Mandasuchus and (?)Stag?iosuchus, 
and fi\e further genera not assigned to families — Parringtonia, 
Teleocrater, Hypselorhachis, Nyasasaunis and Pallisteria. The 
abundant rhynchosaur remains pertain to the primitive genus 
Stenaulorhynchus. 

The abundance of gomphodonts and rhynchosaurs indicates 
that we are dealing with a typical B-type fauna, and the presence 
of Kannemeyeria and of diademodontid and trirachodontid 
gomphodonts suggests a relati\'ely early age. The fauna is ob- 



1973 CHANARES SUMMARY 17 

\iouslv earlier than that found at Ischia^ualasto, and the Santa 
Maria and Chanares faunas are the two South x\merican as- 
semblages with which comparisons might reasonably be made. 
On the whole, it is the Chanares fauna that seems to be the 
closest. The absence of rhynchosaurs in the Chafiares beds re- 
mo\'es one basis of comparison which might have been hoped 
for. Not improbably some of the Manda thecodonts will show 
aflfinities to Chafiares genera when fully described. Crompton 
tells me that some of the Manda gomphodont specimens are 
closely comparable to Massetognathus, but here again we must 
await further publication. It is not unreasonable to expect that 
when the Manda fauna is fully described it will prove to be 
rather similar to that of the Chanares, but of a somewhat earlier 
date. 

In more northern regions — India, Scotland and Nova Scotia 
— are assemblages that contain characteristic elements of the 
B-type fauna but are usually considered as of Late Triassic age. 
In the Maleri beds of India only three named tetrapods are 
present. These are : ( 1 ) a stereospondylous labyrinthodont ge- 
nerically identical with Metoposaurus, common in the Upper 
Triassic of both Europe and North i\merica but otherwise un- 
known in presumed "Gondwana" areas; (2) a phytosaur, diffi- 
cult to assign to a given genus (the systematics of phytosaurs are 
in a confused state) but representing a group unknown else- 
where in "Gondwana" areas except in Morocco; (3) a rhyncho- 
saur Parasuchus [Paradapedon] of an advanced type which 
Chatterjee believes related to Scaphonyx of South America and 
Hyperodapedon of Elgin. The presence of a metoposaur and 
phytosaur in a supposed Gondwana region presents an interesting 
geologic problem, but the question of the age of the Maleri is 
almost equally interesting. 

The Maleri is considered to be "Upper" Triassic; but while 
"upper" in a stratigraphic sense, it may well represent a Carnian 
fauna of our B-type. As regards phytosaurs, they are unknown 
in Europe before the Norian, but this group obviously had a long 
antecedent history (disregarding the question of the age of 
Mesorhinus) . Metoposaurs, again, are "Upper" Triassic, but it 
is not improbable that there may have been older antecedent 
stages in the development of these peculiar stereospondylous 
labvrinthodonts. 

Rhynchosaurs, in the form of the advanced genus Hyper- 
odapedon, are present in the Elgin beds of Scotland, which 
Walker (1961) believes to be of Norian age. His conclusions 



18 BREVIORA No. 413 

mav be correct, and this mav mean a late survival of rhvncho- 
saurs in Europe. But it must be pointed out that there is no 
trace of a rhynchosaur in the Norian Keuper of continental 
Europe, and hence it may be suggested that the Elgin beds are 
pre-Norian, perhaps Carnian in age. The Elgin fauna is a sparse 
one; there is nothing to represent the typical dinosaur fauna of 
the continental Norian (the systematic position of Ornithosuchus 
is questionable ) . Walker's correlation with the Norian is based 
mainly on the presence of Stagonolepis, a close relative of 
Aetosaurus of the continent. But we now know that the aeto- 
saurid pattern was already present in the Ischigualasto beds in 
the form of Aetosauroides [Argentinosuchus], which is still in- 
completely known but appears to be a fully developed member 
of this group. 

Most interesting is the report by Baird (1962 and in litteris) 
of the presence in beds in Nova Scotia which have been corre- 
lated with the Newark series of the Atlantic seaboard of the 
United States, of both of the most characteristic elements of the 
B-type fauna — - rhynchosaurs and a gomphodont jaw ! The 
Newark is a characteristically C-type series, as witnessed not so 
much by the rare dinosaurian fossil remains as by the vast num- 
bers of dinosaur footprints. Are we dealing in these Nova Scotia 
finds with a very late sur\d\'al of gomphodonts and rhyncho- 
saurs? Or — more probably, I think ^ — these supposed Newark 
equi\'alents in Nova Scotia may, in their lower beds, extend 
downward from Norian to Carnian age, into the time of exist- 
ence of the B-faunas. Parenthetically, while the familiar red 
Triassic deposits of the western United States — Chinle, Dockum, 
Popo Agie — are usually considered as of quite Late Triassic 
age, we find in them mainly metoposaurid amphibians and phy- 
tosaurs, and little representation of the abundant dinosaurs found 
in the European Norian, the redbeds of South Africa, the Late 
Triassic of China and, apparently, in the Newark series proper. 
Ls the nature of the faunas of these western beds associated 
with ecological factors or are they of pre-Norian age? 

References Cited 

Baird, D. 1962. Rhynchosaurs in the late Triassic of Nova Scotia. Gcol. 
Soc. Amer. Spec. Paper, 73: 107. 

Beltrao, R. 1965. Paleontologia de Santa Maria e Sao Pedro do Sul, Rio 
Grande do Sul, Brasil. Bot. Inst. Cien Nat. Univ. Fed. Santa Maria, 2: 
1-114. 



1973 CHAN ARES SUMMARY 19 

Bonaparte, J. F. 1966. Chronological survey of the tetrapod-bearing Tri- 
assic of Argentina. Brcviora, Mus. Comp. Zool., No. 251: 1-13. 

. 1967. Comentario sobre la "Formacion Chanares" de la 

cucnca Triasica de Ischigualasto-Villa Union (San Juan-La Rioja) . 
Acta Geol. Lilloana, 9: 115-119. 

— ■ 1972a. Annotated list of the South American Triassic 



tetiapods. Proc. and Papers Second Gondwana Symposium (South 
Africa, 1970) , Pretoria: 665-682. 
. 19721^. Los tetrapodos del sector superior de la forma- 



cion Los Colorados, La Rioja, Argentina. (Triasico Superior) . I Parte. 
Opera Lilloana, XXIIL 1-183. 

BoRTOLUZZi, C. A., AND M. C. Barbarena. 1967. The Santa Maria beds in 
Rio Grande do Sul (Brazil) . Proc. Intern at. Symp. on Gondwana Strat. 
and Paleont.: 169-195. 

Cabrera, A. 1943. El primer hallazgo de terapsidos en Argentina. Notas, 
Museo La Plata, 8, Paleont., No. 55: 317-331. 

Chatterjee, S. 1969. Rhynchosaurs in time and space. Proc. Geol. Soc. 
London, No. 1658: 203-208. 

Cox, C. B. 1968. The Chanares (Argentina) Triassic reptile fauna. IV. 
The dicynodont fauna. Breviora, Mus. Comp. Zool., No. 295: 1-27. 

. 1969. Two new dicynodonts from the Triassic Ntawere forma- 
tion, Zambia. Bull. Brit. Mus. (Nat. Hist.) , Geol., 17: 255-294. 

Frenguelli, J. 1946. Consideraciones acerca de la "Serie de Paganzo" en 
las provincias de San Juan y La Rioja. Rev. Mus. La Plata (N.S.) , 
Geol., 2: 313-376. 

Grober, p. F., and P. N. Stipanicic. 1953. Geografia de la Rej)ublica 
Argentina. Buenos Aires, H (Primera Parte) : Triasico: 13-141. 

Ortiz, A. 1968. Los denominados estratos de Ischichuca como seccion 
media de Formacion Los Rastros. Actas IH Jorn. Geol. Argentina, 1: 
333-339. 

RoMER, A. S. 1960. Vertebrate-bearing continental Triassic strata in Men- 
doza region, Argentina. Bull. Geol. Soc. Amer., 71: 1279^1294. 

. 1966. The Chanares (Argentina) Triassic reptile fauna. L 

Introduction. Breviora, Mus. Comp. Zool,. No. 247: 1-14. 

— ' . 1971. The Chanares (Argentina) Triassic reptile fauna. IX. 



The Chanares Formation. Breviora, Mus. Comp. Zool., No. 377: 1-8. 

1972. Plenary paper. Tetrapod vertebrates and Gondwana- 



land. Proc. and Papers, Second Gondwana Symposium (South Africa, 
1970). Pretoria: 111-124. 

. 1973. Middle Triassic tetrapod faunas of South America. Act. 



IV Congr. Latin. Zool. (Caracas, 1968), II: 1101-1117. 
, and J. A. Jensen. 1966. The Chanares (Argentina) Triassic 



reptile fauna. II. Sketch of the geology of the Rio Chanares-Rio Gualo 
region. Breviora, Mus. Comp. Zool., No. 252: 1-20. 



20 BREVIORA No. 413 

RuscoNi, C. 1951. Laberintodontes Triasicos y Permicos de Mendma.. Rev. 

Mus. Hist. Nat. Mendoza, 5: 33-158. " 

Stipanicic, p. N. 1969. Las sucesiones Triasicas Argentinas. Gondwana 

Stratigraphy, I. U. G. S. Symposium (Buenos Aires, 1967): 1121-1150. 
Walker, A. D. 1961. Triassic reptiles from the Elgin area: SMgdnolepis, 

Dasygnathus and their allies. Phil. Trans. Roy. Soc, London (B) , 244: 

103-204. \ • ■■ 



c 



B R E V I R A 

]ffV^^liii^Y^^^^™^P^^^*^'^^ Zoology 



IAN 7 1974 



US ISSN 0006-9698 



Cambridge, Mas^. 28 December 1973 Number 414 




UNIVfiRSlTt: 

ECOLOGY, SELECTION AND SYSTEMATICS 

Nelson G. Hairston^ 

Abstract. Three different kinds of ecological relationships between newly 
separated species are examined, with the aim of establishing their expected 
effects on the systematic differences between the species involved. In cases of 
slight difference between the habitats of two products of recent speciation, 
selection can be expected to favor specific competitive mechanisms, but 
taxonomic differences would be expected to be slight, and examples of 
hybrid superiority would be common. Where the habitats of the two species 
are markedly different, as along a steep ecological gradient, adaptation to 
the different places will result in species that become broadly overlapping 
in habitat, and taxonomically different in many clearly adaptive characters. 
Although this latter process leads to species with somewhat different food 
habits, it would not lead to food specialization, even if the two species were 
originally limited in abundance by food and in competition for it. True 
food specialization, in the form of monophagy, is most likely to evolve in 
the presence of a superabundance of several kinds of food, owing to in- 
creased efficiency of handling, digestion and metabolism, and is improbable 
among species in competition for food. Closely related monophagous species 
should differ maikedly in a few characters, and hybrids should be inferior. 
Examples of the three situations are described, plethodontid salamanders 
being used for the first two and leaf-mining insects for the third. 

Introduction 

Classically, the relationship between systematics and ecology 
has been approached by first taking systematics as the exploration 
of genomic diversity, and then turning to ecology for explana- 
tions that were secondary to the origin of differences. This 
approach is epitomized by the recent comment to me that the 
reproductively isolated entities within Paramecium aurelia could 

^Museum of Zoology, the University of Michigan 



2 BREVIORA No. 414 

now be considered species because their isoenzyme patterns are 
visibly different. Such a viewpoint surely gets the classification 
much too far away from the biology. As an antidote, I propose 
to examine the relationship from the standpoint that ecology 
provides the set of opportunities that can be exploited by diversi- 
fication of the genome. The approach is not original, as it is 
the basis for the idea of adaptive radiation, but the impact of 
ecology on systematics deserves reexamination. In this, we should 
separate the passive background from the active; that is, those 
factors that set the conditions, and those that are able and likely 
to respond by evolving themselves. These two classes, unfortu- 
nately, will not remain constant for us. For example, it would 
be agreed that the distinction between nonliving and living parts 
of the environment might provide such a preliminary classifica- 
tion, but as far as I can discover, this is not the case. The dis- 
tinction between the vegetation on one hand and the climate and 
substrate on the other is clear enough. The physical gradients 
provide the passive background, making physiological demands 
on a potential additional plant species, and the various com- 
peting species of plants provide the acti\'e counteradapting back- 
ground, making ecological demands. 

However, when we consider the active and passive background 
of animals, particularly carnivorous ones, the distinction between 
plants and the physical environment becomes less important than 
the distinction between both of those on the one hand and other 
animals on the other. Indeed, there are few cases of terrestrial 
predators which are distributed concordantly with even the 
dominant plants, and when this coincidence does occur, the 
plants are used in a nonliving context, as when they are required 
for nest sites. 

This example provides the opportunity to emphasize the dis- 
tinction between selection for physiological adaptation and selec- 
tion in response to the ecological pressures of competition and 
predation. It is to the latter to which I wish to address myself 
principally, but I first give an example of the simultaneous opera- 
tion of both. This will be followed by a description of what 
seems to me to be an unusual opportunity to investigate the 
ecological interaction between one species and several geograph- 
ically varying populations of another, closely related one. From 
that, I hope to be able to generalize some about a fruitful in- 
vestigation of other kinds of systematic consequences of ecological 
phenomena. 



1973 ecology and systematics 3 

^,: An Analysis of the Exploitation of a 

: ' Undimensional Gradient 

As has been emphasized by Dunn (1926), (Hairston, 1949), 
Organ (1961) and others, the evolution of the Dusky Sala- 
manders of the genera Desmognathus and Leurognathus is de- 
scribable in terms of adaptation to a linear series of habitats from 
aquatic to terrestrial. 

This unidimensional array of pertinent physical environments 
facilitates the analysis of each species' most immediate biological 
environment: namely, its closest relatives. 

My own early analysis showed that the coexistence of five 
species was possible, when they used the entire physical gradient 
from completely aquatic to terrestrial. The species involved are 
Leurognathus marniorata, Desmognathus quadrainaculatus, D. 
monticola, D. ochrophaeus and D. wrighti. The distribution of 
the four species of Desmognathus is shown in Figure 1. With 
no further information, however, it was not possible to determine 
whether more species could be accommodated in this presumably 
competitive series. 

Some years later. Organ was able to provide a tentatively 
negative answer when he investigated the ecological distribution 
of the same four species of Desmognathus in an area where a 
fifth species, D. fuscus, was found. He found that at nearly every 
location, the maximum number of species present was four. 
D. fuscus could coexist either with D. quadramaculatus at high 
elevations or with D. monticola away from large streams at lower 
elevations but not with both. 

Thus, the limit imposed by the presumably competitive rela- 
tionships seems to have been reasonably well established, but a 
more detailed look at the data suggests that steepening of the 
moisture gradient may reduce the number of species that can be 
accommodated from the competitive standpoint. At high eleva- 
tions, atmospheric moisture, however expressed, is as great far 
from water as it is over a stream at low elevations (Hairston, 
1 949 ) . This correlates very well with the combined vertical and 
horizontal distributions of the two most terrestrial salamanders, 
Desmognathus ochrophaeus and D. wrighti. D. ochrophaeus is 
confined to a zone near streams at low elevations, none having 
been found more than 15 feet from a stream at elevations below 
3000', but its distribution is unrelated to surface water above 
4500 feet. D. wrighti, with its distribution unrelated to water 
in summer, apparently cannot compete with its congeners close 



BREVIORA 



No. 414 



DISTRIBUTION OV DESMOGNATHUS 



BLACK MOUNTAINS 
(3000-6500') 



NANTAHALA MOUNTAINS 
(2300') 



r~i 



D. quadramaculatus 



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D. monficola 



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15- 20- 25 + 
19 24 



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D. aeneus 



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4 9 14 19 24 



NUMBER OF FEET FROM STREAM 

Figure 1. The ecological distribution of the species of the salamander 
genus Desmognathiis in two different mountain ranges in North Carolina. 



1973 ECOLOGY AND SYSTEMATICS 5 

to Streams at low elevations, and cannot persist away from 
streams there because of the lower moisture. 

It is therefore with some interest that one notes the coexistence 
of four species of Desmognathus at low elevations (down to 
2200 feet) in the Nantahala Mountains. D. wrighti does not 
occur at low ele\'ations, but a study of the ecological distribution 
of the genus shows the presence of a terrestrial species, D. aeneus. 
This species, which is the size of D. wrighti, but more slender, 
was found closer to streams than wrighti usually is in summer, 
but clearly occupies the same general position at the terrestrial 
end of the environmental gradient ( Fig. 1 ) . It seems anomalous 
that it should be present, although D. wrighti is unable to occupy 
the corresponding habitat at low elevations near its range. It 
was postulated above that this inability is related to reduced 
moisture at low elevations. This suggests that there may be a 
climatic \'ariation that permits the existence of a low-altitude 
terrestrial Desmognathus in the Nantahala Mountains. An 
examination of rainfall records reveals that such is the case. In 
the Coweeta Experimental Forest, the location of the distribu- 
tional study, the average annual rainfall ranges from 75 inches 
at 2240 feet to 93. inches at 3870 feet. This is appreciably higher 
than the rainfall at comparable elevations elsewhere in the 
Southern Appalachians. For example, at the foot of the Great 
Smoky Mountains, Bryson City, N.C. has an average annual 
rainfall of 52.12 inches. At the foot of the Black Mountains, 
Montreat and North Fork have 53.61 and 51.78 inches respec- 
tively, and between the Smokies and the Blacks, the French 
Broad Valley receives from 38.45 inches at Enka to 47.61 at 
the Asheville-Hendersonville x\irport. 

Among other locations at comparable elevations in the South- 
ern Appalachians, only the region from Brevard to Highlands, 
N.C. receives as much rain as the general area south and west 
of the Little Tennessee River. Comparable rainfall is found 
elsewhere only at high elevations (71.20 inches at Mt. Mitchell, 
6684' in the Black Mountains, and 81.71 inches at Clingman's 
Dome, 6643' in the Great Smoky Mountains). 

The end of the series of species seems to be determined by 
climate, with high rainfall permitting the addition of a small 
terrestrial species. On larger and higher mountains, when the 
tops are (or once were) covered with conifer forests and rainfall 
is high, the terrestrial species is Desmognathus wrighti, which is 
confined to elevations above 3500 feet; in that part of the moun- 
tains where the rainfall is high, even at low elevations, Des- 



6 BREVIORA No. 414 

mognathus aeneus occupies the terrestrial end of the series. In 
other areas, the series stops with the third species, D. ochro- 
phaeus. It does not appear possible for another species to enter 
the series in the midle, as shown by the situation with D. fuscus 
at \Vhite Top Mountain in Virginia. Competition thus seems 
to determine how similar any pair of species can be and still 
coexist. When the climate would require the next most terrestrial 
species to o\erlap the habitat of D. ochrophaeus to too great an 
extent, only three species are found. 

This situation seems to present an unusually clear example of 
the e\'olutionary exploitation of a simple environmental gradient 
and of the limits of this diversifying exploitation that are set by 
competitive interactions. The limits to "species packing" are 
demonstrated as clearly as post-facto analysis could permit. 

Moreover, it provides a miniature model for the early stages 
in the e\'olution and diversification of the family Plethodontidae. 

Post-Speciational Events : 
Increased Competition or Coexistence? 

The kind of analysis made in the preceding section differs 
from large numbers of published descriptions only in being a 
little more tidy than most. If the field is to progress, such state- 
ments will become the beginning of studies at the interface of 
ecologv' and systematics, rather than representing final conclu- 
sions. The choice among investigations of ecological distribution 
should depend upon the respective opportunities that they pre- 
sent for experimental tests of hypotheses of systematic status or 
ecological processes. One of the points which I wish to make 
most strongly is that experimentation related to ecological inter- 
actions can yield important information about evolutionary 
events, provided that care is taken to select appropriately favor- 
able situations for study. One such situation that seems to be 
especially suitable for field manipulations is represented by two 
species of Plethodon, an exclusively terrestrial genus of sala- 
manders. The location is also the Southern Appalachians. 

Plethodon jordani is endemic to the southern Appalachians. 
Through much of its range, it is confined to higher elevations, 
resulting in a fragmented distribution consisting of a number of 
isolated populations, many of which are morphologically dis- 
tinct from each other. These populations have been studied 
repeatedly, and have been classified as belonging to as many as 
four distinct species (Grobman, 1944). Whenever specimens 



1973 ECOLOGY AND SYSTEMATICS 7 

have been taken from intermediate locations, they are inter- 
mediate in color between the adjacent different populations. 
This discovery led to the eventual inclusion of all of these popu- 
lations within Plethodon jordani and the recognition of seven 
subspecies (Hairston and Pope, 1948; Hairston, 1950). The 
subspecies are no longer recognized, largely because at least some 
of the color characters are distributed independently of one 
another. The situation as it is presently known is described by 
Highton (1970, 1971) and by Highton and Henry (1970), who 
add the electrophoretic patterns of plasmaproteins to the char- 
acters for which distributional data are available. 

Plethodon glutinosus is widespread throughout the eastern 
United States. In the Southern Appalachians, it tends to occur 
at lower elevations than those at which P. jordani does, and I 
ha\'e suggested that the sharp altitudinal replacement of the two 
species is the result of competitive exclusion (Hairston, 1949, 
1 95 1 ) . Although easily recognizable color differences are known 
for at least four geographically distinct parts of the P. glutinosus 
population (Highton, 1962, 1970, 1971), the population in the 
area discussed herein consists of only one of these. P. glutinosus 
is thus morphologically more uniform than is P. jordani. The 
above-mentioned altitudinal separation of the two species is not 
the case everywhere, however. Over the southeastern part of the 
range of P. jordani, the two species occur together over nearly 
the entire range of altitudes available, indicating that competition 
does not play a significant role in their distributions. This ob- 
servation, reported by me for a few vertical transects (Hairston, 
1951) has been confirmed and extended by Highton. The fact 
that in this area P. jordani occurs at lower elevations and P- 
glutinosus at higher elevations than elsewhere strengthens the 
conclusion that in the areas of altitudinal replacement, there is 
intense competition in the narrow vertical zones of overlap. It is 
this geographical difference in ecological relationship between the 
two species that provides an unusual opportunity to investigate 
the phenomenon of competition in the field, and to obtain evi- 
dence on the sequence of evolutionary events accompanying 
competitive interactions between two similar species. 

The above account is oversimplified from the taxonomic stand- 
point. Over most of the area west of the French Broad River, 
the two species are distinct, but Highton has found hybrids at 
appropriate elevations on some of the mountains, and intergra- 
dation is so extensive in the Nantahala Mountains that the local 
form of P. jordani was once described as a subspecies of P. 



8 BREVIORA No. 414 

glutinosus (Bishop, 1941). Highton has called specimens from 
intermediate elexations a hybrid swarm. Two detailed vertical 
transects in the Southeastern Nantahalas at Coweeta Experi- 
mental Forest show that simple explanations of the relationship 
are unlikely to be satisfactory. The forest has two more or less 
parallel roads that ascend to the top of the mountain. The roads 
di\'erge slowly from the foot of the mountain at 2200 feet, being 
a little more than one mile apart at 3200 feet and around two 
miles apart at the points where they reach the top of the ridge at 
4100 and 4500 feet, respectively. In October, 1971, a transect 
was carried out along the more northern road, to be referred to 
as the Shope Creek Road. The con\'entional expectation would 
be of continuously increasing similarity to P. jordani and de- 
creasing similarity to P. glutinosus with increasing altitude. The 
comparison was made on the basis of color alone, no other 
known character being of value in that part of the range. Four 
different color characters are possible. P. jordani is character- 
ized by red legs and a pale belly; P. glutinosus has extensive 
white spotting, especially on the sides, and a black belly. A 
population of P. jordani 10-15 miles to the east has extensive 
brassy spotting on the back, as well as some white spotting on the 
sides, but at present seems to be distributed discontinuously from 
the Nantahala population. A few specimens from the transect 
had brassy spots, but were too few to yield meaningful informa- 
tion. Arbitrary scales were established to compare the relative 
amount of red on the legs, white spotting, and darkness of belly 
color. Six to 20 specimens were collected at each of 11 eleva- 
tions from 2200 to 4300 feet. For each collection, an average 
intensity of each character was established by five different ob- 
servers, and the results pooled. The three characters changed in 
exactly the same way along the transect. The results for two of 
them are shown in Figure 2. The reversal of the expected trend 
led to a transect of the southern road (Ball Creek) in 1972. 
The results, shown in Figure 3, conform to the original expecta- 
tion, but do not agree with the Shope Road transect, which was 
repeated in 1972 with \irtuallv identical results to those obtained 
in 1971 (Fig. 2). 

Although the 3800-foot site is located on an east-west ridge, 
the same is true of all higher sites, and no obvious vegetational 
differences could be seen to account for the difference between 
the transects — impressions confirmed in the records from 69 
widely dispersed rain gauges (Dils, 1957). 

\Vhate\er the eventual explanation for these anomalous data. 



1973 



ECOLOGY AND SYSTEMATICS 



ALTITUDINAL VARIATION IN COLOR CHARACTERS IN PLETHODON 
ALONG SHORE CREEK WATERSHED 



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. 












I 










_ 


2 




O— . 






; 




^,-^-' 












< 






-* 


. y 


^,---r^ 


























_..d' 
























V'"' 


















4 






, 




, 




• 


1 1 


1 ' 


, 


, 





2200 2400 2600 2800 3000 3200 3400 3600 3800 4000 4200 

ALTITUDE (feet) 

Figure 2. The vertical distribution of two color characters in the sala- 
mander genus Plethodon along the Shope Creek transect in the Nantahala 
Mountains in North Carolina. The scale for white spotting has been in- 
verted because white spots are characteristic of the low-altitude species. 



10 



BREVIORA 



No. 414 



ALTITUDINAL VARIATION IN COLOR CHARACTERS IN PLETHODON 
ALONG BALL CREEK WATERSHED 




2300 2500 2700 2900 3100 3300 3500 3700 3900 4100 4300 

ALTITUDE (feet) 




2300 2500 2700 2900 3100 3300 3500 3700 3900 4100 4300 

ALTITUDE (feet) 

Figure 3. The vertical distribution of two color characters in Plethodon 
along the Ball Creek transect, for comparison with Figure 2. 



1973 ECOLOGY AND SYSTEMATICS 11 

they reflect complications in the relationship between the two 
species, and further in\'estigations may reveal or at least suggest 
\'ery local selective forces. 

The situation in the Nantahalas gives a strong indication of 
close taxonomic relationship between P. glutinosus and P. jor- 
dani, and is thus useful information in suggesting ecological and 
especially evolutionary questions about the two species elsewhere 
in the Southern Appalachians where hybridization is absent or 
very rare. 

Current ev^olutionary theory would explain the observed eco- 
logical distributions in these other areas in the following manner : 
assuming, as seems likely, that Plethodon glutinosus and P. jor- 
dani share a common ancestor in the not very remote past, the 
speciational event separating them left two species with adjacent 
geographical ranges and very similar ecological requirements. 
Plethodon jordani presumably occupied the southern part of the 
Blue Ridge physiographic province, and the relevant part of 
P. glutinosus occupied the adjacent part of the Piedmont prov- 
ince. With a warming climate, glutinosus has invaded the val- 
leys of the Blue Ridge province, but competition from jordani 
has prevented glutinosus from extending its range to the tops 
of at least some of the mountains, notably the Great Smoky 
Mountains, the Black Mountains, and the Unicoi Mountains. 
Throughout most of the rest of the area of common distribution, 
one or both species have evolved into ecologically divergent 
directions, with the result that competitive exclusion no longer 
operates, and the two species coexist over a wide range of eleva- 
tions. This situation would represent character displacement in 
the use of some ecological requirement as yet unidentified. In 
the areas of competitive exclusion, the vertical overlap of 200 
feet represents the uncertainty of outcome of competition owing 
to climatic variability, P. jordani being favored by cool, wet 
years and P. glutinosus by the reverse conditions. 

' Thus, in conventional theory and as far as numerous observa- 
tions have revealed, we have the same two species coexisting in 
some areas and in intense competition in others. Geographic 
variation in color of P. jordani provides independent identifica- 
tion of representatives from the two ecologically different popu- 
lations, and this and other features make it feasible to undertake 
experimental manipulations to test the accuracy of the interpre- 
tations that I and others have made of the present distributions 
of the local populations of the two species. This should be done 
by reciprocal removal experiments and by exchanging numbers 



12 BREVIORA No. 414 

of Plethodon jordani between the two areas of presumably dif- 
ferent ecological relationships. Inasmuch as they difTer in color 
pattern, the introduced individuals and their descendents would 
be readily identifiable for an indefinite number of years after the 
start of the experiments. 

The most obvious first test of the interpretations would be to 
remo\'e each species separately from different plots in the differ- 
ent areas where competition is and is not expected. If the in- 
terpretation is correct, the remaining species should show a much 
greater response in the area of narrow vertical overlap than in 
the area of wide vertical o\'erlap. 

Whatever the outcome of these simple removal experiments, 
they would help resoh^e an implicit contradiction in ecological 
theory. This is the conflict between the often used theory that 
distributional overlap between closely related species implies an 
appreciable amount of competition (Levins, 1968; MacArthur, 
1968) and the converse that the same overlap implies that com- 
petition is reduced or absent (Crombie, 1947; Hairston, 1951; 
Brown and Wilson, 1956; MacArthur, 1972: 29 ff). This con- 
flict is rarely stated overtly, but its resolution could have a pro- 
found effect on ecological theory, including much that has been 
written about niche breadths and community matrices. 

The implications of the simple removal experiments are more 
directly ecological than they are evolutionary. The combination 
of ecological and systematic situations provides the opportunity 
for more sophisticated experiments whose results could yield im- 
portant insights into the recent influence of natural selection on 
the direction of evolution in the several populations of Plethodon 
jordani. These experiments would consist of reciprocal trans- 
plants of populations of P. jordani between an area of narrow 
o\'erlap and one of wide overlap. The subsequent changes in the 
transplanted jordani populations and in the P. glutinosus popu- 
lations newly exposed to the foreign jordani would re\eal the 
direction of recent evolution with respect to interspecific com- 
petition. 

If P. jordani from the area of wide overlap survived in the 
area of narrow overlap, and the P. glutinosus population in- 
creased, the interpretation would be that in the area of wide 
overlap, P. jordani has evolved so as to decrease its competitive 
interaction with glutinosus. If P. glutinosus has evohed in the 
same way, the reciprocal experiment should result in no change 
in the glutinosus population, and it might result in an increase in 
the jordani population introduced from the area of narrow over- 



1973 ECOLOGY AND SYSTEMATICS 13 

lap, because the jordani would not be meeting as much compe- 
tition as it had been experiencing before the experiment. 

Con\ersely, if the P. jordani transplanted from the area of 
narrow o\erlap increases in the area of wide overlap at the ex- 
pense of the local P. glutinosus, it would be necessary to conclude 
that recent e\'olutionary history had produced a specialization 
in jordani for some specific competitive mechanism. 

A decrease in and eventual disappearance of jordani moved 
from the area of wide overlap, combined with an increase in the 
local glutinosus, would be interpreted to mean the evolution of a 
specific competitive mechanism in that population of glutinosus. 

The complete set of possible experimental outcomes and their 
interpretations is given in Tables 1 and 2. Specifically omitted 
from the tables are the highly necessary controls. For the re- 
moval experiments, the only controls required are undisturbed 
plots containing both species. The reciprocal transplantation of 
populations of P. jordani will require elaborate controls. First, 
one must be satisfied that the salamanders can be moved at all 
and continue to thrive. This will require transplanting animals 
within an area where their ecological relationships appear to be 
constant. Assuming the success of such an experiment, it will 
also be necessary to provide assurance that they are physiologi- 
cally capable of existing in the remote area where the competi- 
tive relations are presumably different. For this control, it will 
be necessary to first remove both species from a plot and then 
introduce the foreign jordani. Its survival would assure an 
interesting result on those plots where it was introduced into 
contact with glutinosus. The failure of any of these controls 
would of course mean that the main experiment in reciprocal 
transplantation of populations was a failure. This is a gamble 
taken by anyone planning a controlled experiment. 

If the controls succeed, the experiment should permit one to 
choose with confidence between the following hypotheses: First, 
that after speciation natural selection has favored ecological 
diversification with resultingly greatly lowered competition and 
a greatly increased area of coexistence; and second, that after 
speciation and reinvasion, natural selection has favored the de- 
velopment in at least one species of mechanisms to increase its 
competitixe ability and thus exclude the congener from all or 
nearly all of its range. The ability to choose between the two 
hypotheses would greatly advance our ability to interpret sys- 
tematic-distributional data from a large array of situations where 
post facto conclusions are all that can be expected. 



14 



BREVIORA 



No. 414 



TABLE 1. The plan and possible outcomes with their interpretations of 
experimentation in the area where Plethodon jordani and P. glutinosus over- 
lap broadly in vertical distribution. All controls are described in the text. 



MANIPULATIONS 


OUTCOME 


INTERPRETATION 






a. 


Local glutinosus has a competi- 






Disappearance 


tive adaptation to foreign 






of moved 


jordani and local jordani has 






jordani. 


evolved ecological character 
displacement. 






(I) 




1. 




Combined with a decrease in 




Replace 




abundance of glutinosus, means 




with 




that introduced jordani had 




jordani 


b. 


evolved a specific competitive 




from area 


Persistence 


mechanism against glutinosus. 




of narrow 
overlap. 


of moved 
jordani. 




A. 


(II) 
Combined with constant gluti- 
nosus population, means that 


Remove 
jordani. 












local glutinosus has evolved eco- 








logical character displacement. 






a. 


Means that there was no 






No change in 


competition with jordani. 




2. 


abundance of 






Leave 


glutinosus. 






local 

glut 171 OS us 








b. 


Means that there was some 




alone. 


Increase in 
abundance of 
glutinosus. 


competition at a low level. 






a. 


Means that there was no 






No change 


competition with glutinosus. 




1. 


in abundance 


(Reciprocal of A 2 a) 


B. 


Leave 


oi jordani. 




Remove 


local 










glutinosus. 


jordani 
alone. 


h. 
Increase in 


Means that there was some 
competition with glutinosus at a 






abundance 


low level. (Reciprocal of A 2 b) 






of jordani. 





1973 



ECOLOGY AND SYSTEMATICS 



15 



TABLE 2. The plan and possible outcomes with their interpretations of 
experimentation in the area where Plethodon jordani and P. glutinosus have 
a narrow zone of vertical overlap. All controls are described in the text 



MANIPULATIONS OUTCOME 



A. 

Remove 
jordani. 



B. 

Remove 

glutinosus. 



I. 

Replace 
with 
jordani 
from area 
of wide 
overlap. 



2. 
Leave 
local 

glutinosus 
alone. 



1. 

Leave 
local 
jordani 
alone. 



Disappearance 
of moved 
jordani. 



Persistence 
of moved 
jordani. 



No change in 
abundance of 
glutinosus. 



h. 
Increase in 
abundance of 
glutinosus. 



a. 

No change 
in abundance 
of jordani. 



b. 

Increase in 
abundance 
of jordani. 



INTERPRETATION 



Local glutinosus has a specific 
competitive adaptation to all 
jordani; glutinosus should 
increase in abundance. 



(I) 
If glutinosus increases in 

abundance or remains stable, 

indicates that introduced 

jordani has evolved ecological 

character displacement with 

respect to all glutinosus. 



(II) 
If glutinosus decreases, indicates 
specific adaptation by area I 
glutinosus to coexist with all 
jordani; especially strong if 
combined with A 1 b (II) of 
Table 1. 



Means that original hypothesis 
of competition was false. Total 
distribution pattern hard to 
interpret. Expect other bad 
results. Habitat disturbed? 



Confirms original hypothesis of 
competition. Should increase 
more than in A 2 b of Table 1. 



Means that original hypothesis 
of competition was false, 
especially with A 2 a. (Same 
interpretation) 



Confirms original hypothesis of 
competition; jordani should 
increase more than in B 1 b of 
Table 1. 



16 BREVIORA No. 414 

Specialization and the Results of 
Ecological Interactions 

The e\'olutionary result of competitive interactions has been 
the subject of a great deal of speculation, most of it stressing 
specialization for different resources. This interpretation requires 
scrutiny, since it implies that differential specialization is a prob- 
able result of competition for resources, and the observation of 
different food habits among coexisting related species has been 
interpreted as a\'oidance of competition. 

Such an interpretation, to be accepted even provisionally, 
should require an examination of alternate hypotheses to explain 
the observation. One such hypothesis that has not been explored 
adequately, is that specialization carries advantages in efficiency 
of handling, digesting or metabolizing the food, and that com- 
petition need not be invoked at all. Thus, competition is easily 
shown not to be a necessary condition for the evolution of food 
specialization. The subject will be pursued to examine the ques- 
tion of the sufficiency of competition as an explanation. If spe- 
cialization for one kind of food is regarded as a derived state, as 
either of the aboxe hypotheses assumes, then polyphagy must be 
regarded as the starting point for any reconstruction. Assuming 
that such is the case, and that the members of a species are ex- 
periencing intraspecific competition for food, an individual of this 
species which tended to specialize would be at a disadvantage 
whene\er its specialty became scarce, since, in becoming a spe- 
cialist, it would be expected to lose some ability to handle or 
digest the remaining kinds of food. The only ways for such a 
specialist to remain at an advantage would be to begin by being 
so efficient at obtaining the special food as to overcome the 
expected periodic scarcity, or else in some way to avoid the ex- 
pected trade-off in efficiency with regard to other kinds of food. 
The probability appears to be very low in either case. Thus, for 
food-limited species polyphagy should be the rule. 

With an initially polyphagous species that has a superabun- 
dant supply of food, the situation is quite different. Any geno- 
type increasing specialization is likely to be favored because of 
the benefits of increased efficiency. No penalty is attached to 
this tendency, because under the terms stated, none of the various 
kinds of food is ever in short supply. Therefore, contrary to 
routinely accepted theory, specialization for different foods 
should be characteristic of species that are not in competition, 
and the claim is hereby advanced that prior competition is 



1973 ECOLOGY AND SYSTEMATICS 17 

neither a necessary condition nor a suflficient one to explain the 
coexistence of closely related species each specializing on a dif- 
ferent food. 

How is such a claim to be tested? One way would be the 
laborious one of field experimentation testing for the means of 
limitation of population size in a large series of related species, 
some of which were monophagous and some polyphagous. If 
the former are consistently limited through means other than the 
supply of their food resources, and the latter show a consistent 
tendency to be food-limited, the claim would be strongly sup- 
ported. Rigorous proof of a series of events in evolutionary his- 
tory is, of course, not possible, and in the present instance, even 
if the experiments had the expected outcomes, the counterclaim 
could always be made that the specialists had been released from 
competition by becoming specialists and therefore would have 
to be limited in abundance by some other factor. 

A post facto test of the claim that food specialization implies 
the absence of prior competition for food can be suggested in the 
following manner. Among a number of species whose food is 
well documented, there should be no particular relationship be- 
tween the degree of specialization and the number of specialized 
species per species of food. If, on the other hand, specialization 
represents an evolutionary "escape" from competition for food, 
the advantage gained should be reflected in a tendency to be the 
only such species feeding on the food species in question. Thanks 
to an extensive table by Needham, Frost and Tothill (1928), 
this test can be made in the case of leaf-mining insect species. 
There are 435 species of plants that serve as hosts. Of these 289 
are fed on by only one species of leaf miner; 82 are fed on by 
two species, and 64 are fed on by three or more species of leaf 
miners. On the hypothesis that the distribution of the insect 
species is by chance among the three groups of plant species, the 
expected distribution can be calculated by tabulating for each 
insect species its host plant species with respect to the number of 
insect species that the host plant supports. Thus, for each spe- 
cialist, only one plant species will appear in the table; for those 
feeding on two plant species, both plant species will appear in 
the table, and the same system continues for insects feeding on 
three or more species of plants; each plant species will appear 
separately in the appropriate part of the table. After the removal 
of those records involving plants determined only to genus, and 
prorating those appearing more than once in the table, there 
remain 426 records of the plant species, classified according to 



18 BREVIORA No. 414 

TABLE 3. The number of species of plants attacked by varying numbers of 
species of leaf-mining insects. The insect species have been separated ac- 
cording to the specificity of their food habits. The figures in the table have 
been calculated on the assumption of no relationship between the degree of 
specialization of the insect and the number of species of insects supported by 
its food plant (s) . 

Number of species of insect per species 
2 of host plant 

U o - - 

O a. U 

^ w y: 

«4-l — — 

^ ^ -y. 

^ (-1 ^ 
^ O y. 

TABLE 4. The observed distributions of plant species for comparison with 
the expected distributions in Table 3. 

Number of species of insect per species 
60 of host plant 

O '> w 

a- ~ ' 





1 


9 


3 


or more 


1 


99.47 


28.31 




21.87 


2 


47.21 


13.44 




10.38 


3 or more 


136.41 


38.83 




30.00 



*^ -y. 






"ti a- 





1 


2 


3 


or more 


1 


94.00 


37.50 




18.31 


9 


48.00 


11.00 




12.10 


3 or more 


134.00 


38.50 




32.95 



Z o 



the number of insect species feeding on them. In the absence 
of a relationship between specificity of feeding by the insect and 
the number of insect species supported by the host, these 426 
records should be distributed in the ratio 289 : 82 : 64 for each 
group of insects : those found on one species of plant, those found 
on two species and those' found on three or more species. The 
expected distributions are given in Table 3. 

If specialized species of insects tend to specialize on plant spe- 
cies for which there is little competition, there should be an 
excess of species in the first column for species with one host, and 
a corresponding deficiency in the third column for the same row. 
That such is not the case is shown in the observed distribution 
(Table 4). Three of the specialists are confined to a plant spe- 
cies that supports them and ten other species of leaf miners; 
four are confined to a plant species that supports them and 
eight other species of leaf miners. At the other end of the scale, 
one species of leaf miner which lives on 37 different plant species 
is the only species feeding on 19 of these plants. Thus, these data 



1973 ECOLOGY AND SYSTEMATICS 19 

provide no support for the hypothesis that specialization for spe- 
cific food items arises as a direct result of interspecific competi- 
tion, and the data do support the hypothesis that such specializa- 
tion arises in the presence of ample food of various kinds. The 
data, incidentally, are also consistent with other kinds of evi- 
dence indicating that the terrestrial herbivore trophic level is 
predator-limited as a whole (Hairston, Smith, and Slobodkin, 
I960). 

It is now worthwhile to examine the kinds of divergence that 
would be likely under the selective force of interspecific compe- 
tition. It is assumed, and will probably be conceded, that com- 
petition is likely to be most intense between close relatives, here 
interpreted as those most recently separated by speciation. It is 
further assumed that newly separated competing species will be 
in contiguous but largely nonoverlapping ranges. If the differ- 
ences between the adjacent places were great enough, the pro- 
cess of adaptation to the separate local conditions would be 
likely to result in species that were different in many ways, in- 
cluding the acquisition of different kinds of food, even if both 
species were limited in abundance by their food supplies. Selec- 
tion might now favor either of two quite different courses: the 
production of competitive mechanisms specifically against the 
neighboring species, or further divergence by each species in ob- 
taining food in those parts of the others' range most like its own. 
The first would sharpen the boundary between the two species, 
as is the case with Plethodon jordani and P. glutinosus over parts 
of their distribution; the second course would be expected to 
lead to broadly overlapping but different ecological distributions, 
such as are exemplified by the species of Desmognathus. These 
two courses, as well as the third and noncompetitive course pro- 
posed earlier, would have quite different consequences from the 
standpoint of systematics. The continued highly competitive situ- 
ation should result in few differences, and it is easy to imagine 
situations in which hybrids would be at an advantage. The two 
spdcies of Plethodon in the Nanthala Mountains may provide an 
example. Where the species become differentially adapted to 
place, it would be expected that many differences would be 
favored, and that eventually these would become the large dif- 
ferences that characterize higher categories. It would be easy to 
place Desmognathus aeneus and D. quadramaculatus in different 
genera, were it not for the existence of two species intermediate 
between them in morphology. Finally, in the noncompetitive 
situation, it might be expected that selection would produce few 



20 BREVIORA No. 414 

differences, but those would be ver\- distinct, and would be such 
as to put hybrids at a severe disadvantage. 

What is being suggested here is that an analysis of the sys- 
tematic and distributional relationships provides clues to the eco- 
logical forces that have been operating on the species in question. 
In the case of one such situation, there has been proposed a series 
of experimental tests designed to permit a choice among the eco- 
logical and selectional events that led to the present systematic 
relationships. Without such planned experiments, we are com- 
mitted at best to accepting "natural experiments," the conditions 
of which may be unknown to us, and which nearly always lack 
the elements of controls and of experimental design that promote 
definitive answers to specific questions. Manipulations will not 
be possible for all situations, but if the different ecological causes 
and their systematic effects that I have suggested can be con- 
firmed for a few specific cases, predictive power would be added 
to the simple analyses to which we are now confined. 

References Cited 

Bishop, S. C. 1941. Notes on salamanders with descriptions of several new 
forms. Occ. Papers Mus. Zool., Univ. of Mich., No. 451: 1-21. 

Brown. W. L., and E. O. Wilson. 1956. Character displacement. Syst. 
Zool., 5: 49-64. 

Crombie, a. C. 1947. Interspecific competition. J. Anim. Ecol., 16: 44-73. 

DiLS, R. E. 1957. The Coweeta Hydrologic Laboratory. U.S. Dept. Agri- 
culture Forest Service Southeastern Forest Experiment Station, Asheville, 
N.C. ii + 40 pp. 

Dunn, E. R. 1926. The salamanders of the family Plethodontidae. Smith 
College Anniversary' Pubis, xii + 441 pp. 

Grobman, a. B. 1944. The 'distribution of the salamanders of the genus 
PletJiodon in the eastern United States and Canada. Ann. New York 
Acad. Sci., 45: 261-316. 

Hairston, N. G. 1949. The local distribution and ecology of the pletlio- 
dontid salamanders of the Southern Appalachians. Ecol. Monogr., 19: 
47-73. 

. 1950. Iiucrgradation in Appalachian salamanders of the 

genus Plethodon. Copeia, 1950(4) : 262273. 

1951. Interspecies competition and its probable influence 



upon the vertical distribution of Appalachian salamanders of the genus 
Plethodon. Ecology, 32: 266-274. 
, AND C. H. Pope. 1948. Geographic variation and spccia- 



tion in Appalachian salamanders {Pletfwdon jordatii Group) . Evolu- 
tion, 2: 266-278. 



1973 ECOLOGY AND SYSTEMATICS 21 
, F. E. Smith, and L. B. Slobodkin. 1960. Community 



structure, population control, and competition. Amer. Natur. 94: 421- 
425. 

HiCHTON, R. 1962. Revision of North American salamanders of the genus 

Plethodon. Bull. Fla. State Museum, 6: 235-367. 
. 1970. Genetic and ecological relationships of Plethodon jor- 

dani and P. glutinosus in the Southern Appalachian Mountains. 

Pp. 211-241 in Th. Dobzhansky, M. K. Hecht, and W. C. Steere (eds.) , 

Evolutionary Biology, Vol. 4. New York: Appleton-Century-Crofts. 
. 1971. Distributional interactions among eastern North Amer- 



ican salamanders of the genus Plethodon. Pp. 139-188 in P. C. Holt 
(ed.) , The Distributional History of the Biota of the Southern Appa- 
lachians. Research Div. Monograph 4. Blacksburg, Va.: Virginia Poly- 
technic Inst. 

-, AND S. Henry. 1970. Variation in the electrophoretic migra- 



tion of plasma proteins of Plethodon jordani, P. glutinosus, and their 
natural hybrids. Pp. 241-256 in Th. Dobzhansky, M. K. Hecht, and 
W. C. Steere (eds.) , Evolutionary Biology. Vol. 4. New York: Appleton- 
Century-Crofts. 

Levins, R. 1968. Evolution in Changing Environments. Princeton, N.J.: 
Princeton Univ. Press, x + 120 pp. 

MacArthur, R. 1968. The theory of the niche. Pp. 159-176 in R. C. 

Lewontin (ed.) , Population Biology and Evolution. Syracuse, New York: 

Syracuse University Press. 
. 1972. Geographical Ecology. New York: Harper & Row. 

xviii -f 269 pp. 

Needham, J. G., S. W. Frost, and B. H. Tothill. 1928. Leaf-mining in- 
sects. Baltimore, Md.: Williams and Wilkins Co. viii + 351 pp. 

Organ, J. A. 1961. Studies on the local distribution, life history, and pop- 
ulation dynamics of the salamander genus Desmognathus in Virginia. 
Ecol. Monogr., 31: 189-220. 



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B R E V I O R A 

Miiseiin:j^^j^f^£jim^a^ Zoology 

■■^ ^BAfifeYr 0006-9698 

Cambridge, MAS^^fiJ^f^I^ECj^i^^ER 1973 Number 415 

THE EJW^fiJ^ON OF BEHAVIOR 
AND THE RoKe'dF'bEHAVIOR IN EVOLUTION 

M. MOYNIHAN^ 

Abstract. Modern behavior studies are, or should be, primarily concerned 
with problems of causation. The immediate causes of particular behavior 
patterns are being analyzed at the physiological and biochemical levels. The 
ultimate causes, selection pressures, are being studied by ecologists and 
ethologists. Unfortunately, there is little contact between the two lines of 
investigation at the moment. Doubtless a new synthesis will be achieved in 
the future. It does not, however, appear to be imminent. In the meantime, 
the results of behavior studies in th^ field or in the laboratory in semi- 
natural conditions can still be of use to the evolutionary biologist. They 
may be most helpful in revealing the details, mechanics, of certain ecological 
processes, which are themselves the regulators or determinants of evolutionary 
events. Some examples from recent work on cephalopods, monkeys, and birds 
may illustrate the sorts of data that are both available and relevant. 

Introduction 

I have been asked to talk about my own work on animal 
behavior and related subjects, and also to say something about 
possible further developments of behavioral studies in general. 
The prospect of thus anticipating the future is not entirely grati- 
fying. It seems to me that current research on animal behavior 
has reached a difficult, awkward, almost embarrassing stage. As 
is the case with any subject, there are numerous false starts and 
unrewarding pursuits. Some questions being asked by workers 
in the field are hardly worth posing. The answers are self- 
evident or easily predictable. Some other questions are devoted 
to more significant problems, but apparently cannot be answered 
with the techniques currently available, at least not the tech- 
niques actually being used. More important, the various kinds 

^Smithsonian Tropical Research Institute 



2 BREVIORA No. 415 

of studies that are proving to be useful and successful are becom- 
ing increasingly disparate in both methods and objectives. 

This anomalous situation is, of course, the result of historical 
factors. It might be instructive, therefore, to give a brief resume 
of some aspects of the past, in order to explain the present unease 
and to pro\'ide or re\ eal a reasonable rationale for some of the 
continuing work — my own included. 

Many biologists, the majority of evolutionary biologists and 
"natural historians," probably would agree that the most stimu- 
lating school of behaviorists in this century was that of the "ethol- 
ogists." Ethology as such may be difficult to define. In theory, 
the term could be applied (without paying too much attention 
to its classical deri\ation) to the whole of the science of behavior. 
In fact, it is usually restricted to a particular approach to the 
subject, based upon Darwin (1872) and other pioneers such as 
Heinroth (1911), Whitman (1899 and 1919), Huxley (1914), 
and Craig (1918), and perhaps influenced by some early ideas 
of Freud or his predecessors, but largely developed in continental 
or Teutonic Europe in the 1930's and 1940's and subsequently 
widely diffused, first in the English-speaking world and then 
elsewhere in the next decade. 

This school was distinguished by a concentration upon large 
segments or sequences of behavior in natural or semi-natural 
conditions, especially social (inter-indi\idual behavior and the 
reactions that were called at the time "innate," i.e., species- 
typical or (often by implication) species-specific. Among the 
better known products of the school which may ser\^e to illustrate 
its original range of interests were papers by Lorenz {e.g., 1931, 
1935, 1941), Lorenz and N. Tinbergen (1938), N. finbergen 
(1932, 1935, 1936, 1939, 1940), Makkink (1936), Kortlandt 
(1940), Seitz (1940 and 1941), and Baerends and Baerends 
(1950). 

Another characteristic of the first ethological studies was a pre- 
occupation with causes, not only long-term components such as 
selection pressures affecting beha\'ior in the course of evolution 
but also short-term or even immediate causes, external and in- 
ternal states and stimuli and internal mechanisms producing 
particular acts at particular instants in time. The latter interest 
entailed a considerable amount of rather ambitious and detailed 
model-building, the dc\elopment of concepts and terms such as 
"Innate Releasing Mechanism," "reaction specific energy," "dis- 
placement" activities, and "hierarchies" of instincts. The state of 
the art at this stage is beautifully summarized in N. Tinbergen 



1973 EVOLUTION AND BEHAVIOR 3 

( 1951 ) . Unfortunately, most of the models proved to be descrip- 
tive of the overt manifestations of behavior but not explanatory 
or usefully predictive. They did not correspond very closely to 
the actual e\'ents within a behaving animal. (This sort of dis- 
crepancy between the perceived and the real is an occupational 
hazard of model-building. There may be comparable gaps in 
ecological models — a topic that will be mentioned later. ) 

The responses of ethologists to their logical and methodological 
difficulties were exceedingly diverse : 

1. The original mainstream of effort was impeded and re- 
duced but did not dry up completely. There were hopeful and 
ingenuous attempts to redefine and refine the classic concepts 
(see, for instance, Bastock et al., 1953; Hinde, 1954a and 1954b; 
Morris, 1957; Blest, 1961). Some of these attempts may have 
been helpful in minor ways, but I think that it would be fair to 
say that they did not do very much to resolve the basic dilemma. 
There was a push to render descriptions more precise, by adop- 
tion of mathematical and pseudo-mathematical means of nota- 
tion, often with an infusion of information theory and cybernetic 
terminology, and by increased* use of improved photographic 
and other kinds of recording equipment. Examples are too nu- 
merous to cite, but many can be found in recent issues of the 
journals "Behaviour" and "Animal Behaviour" and the bibli- 
ographies of the general surveys of Hinde (1970), Eibl-Eibesfeldt 
(1970), and Marler and Hamilton (1967). All too often, they 
have merely told us what we already knew or assumed, at dis- 
tressingly greater length and elaboration than we were prepared 
to cope with. 

2. Perhaps a more practical response was switching of atten- 
tion to groups of animals and special problems that had been 
neglected in earlier years. Several bends in the river or new 
channels which are in some danger of becoming oxbows but are 
at least picturesque. There has been a great deal of strictly 
etholoarical work on a variety of "lower" mammals such as mar- 
supials, rodents, and carnivores [e.g., Kaufmann, in press; Klei- 
man, 1972; Leyhausen, 1956; Kruuk, 1972; Schaller, 1972; 
Ewer, 1963, 1968, and 1973), and an enormous proliferation of 
studies and surveys of primates {e.g., Altmann, 1967; Chance 
and Jolly, 1970; Crook, 1970; DeVore, 1965; Dolhinow, 1972; 
Imanishi and Altmann, 1965; Jay, 1968; Jolly, 1966 and 1972; 
Kummer, 1968 and 1971; van Lawick-Goodall, 1971; Morris, 
1967a; Movnihan, in press a; Fetter, 1962; Poirier, 1972; Rey- 
nolds, 1968; Rosenblum and Cooper, 1968; Rowell, 1972; 



4 BREVIORA No. 415 

Schaller, 1963; Struhsaker, 1969). Many of these papers were 
indirect reflections of a strong interest in human beha\ior, both 
as it is and as it may be supposed to have been at some earlier 
time in the Pliocene or Pleistocene; and there have also been 
attempts to apply conventional ethological insights to some of the 
urgent problems of modern man {e.g., Lorenz, 1963; Russell 
and Russell, 1968; Morris, 1967b; Martin, 1972) with amusing 
results (critics have tended to dismiss both the good and bad 
suggestions and interpretations as impertinent sensu stricto, but 
it may be hoped that some of them will eventually be incorp- 
orated into the intellectual background of the well-informed 
citizen ) . 

The most fashionable of the special subjects has been what 
might be broadly called "communication." Different aspects of 
the subject ha\'e been tackled at many different levels and in 
many different areas. There have been analyses of the various 
ways in which information, true or false, can be transmitted 
among individuals of the same or different species, and also of 
the means by which transmission can be prevented or inter- 
rupted. One of the aspects of interspecific communication that 
has attracted investigation and speculation is mimicr\ , not onh' 
the long known Batesian and Mullerian types but also aggressive 
and social and e\'en more recondite forms. Relevant publications 
include Brower et al. ( 1 960, and many other papers from the 
same school); Rand (1967); Robinson (1969); Moynihan (in 
press b), and an extensive discussion and summary in Wickler 
(1968). The methods by which predators discover and recog- 
nize prey, with or without the baffles of mimicry and crypsis, 
have been studied by many workers. The papers of Robinson 
and his collaborators {e.g., 1969, 1971a, 1971b) reveal some of 
the factors that may corne into play. Research on intra-specific 
communication has been primarily concerned with the e\en more 
variegated "languages" used in more complex social situations 
("social" in the ever\^ day sense of the term). It has involved 
description, decipherment, and efforts to detect and formulate 
the general rules, the "grammar and syntax," of a multiplicity 
of signal systems. There have been sur\'eys and comparisons of 
the signals of different groups of animals {e.g., Tembrock, 1959; 
Lanyon and Tavolga, 1960; Busnel, 1963; Sebeok, 1968), some- 
what abstract discussion of theorv {e.g., W. J. Smith, 1965 and 
1969; Moynihan, 1970; Cullen, 1972; Mackay, 1972), and 
detailed accounts of particular systems, ranging from the phero- 
mones of insects {e.g., the work of E. O. Wilson and his col- 



1973 EVOLUTION AND BEHAVIOR 5 

leagues) through bird "song" {e.g-, Thorpe, 1961 ; Hinde, 1969) 
to the non-\erbal movements and expressions of children and 
adults in contemporary western and other human societies {e.g., 
Gofifman, 1971; Blurton Jones, 1967 and 1972; Argyle, 1972; 
Eibl-Eibesfeldt, 1972). These studies may have implications for 
related fields. They have, for instance, at least made available 
to "real" linguists such as Chomsky, Lenneberg, etc., some useful 
background material and evolutionary perspective. 

3. However valuable such works may be, they would appear 
to be di\Trsions from the classical behavioral point of view. 
Most active students are proceeding, and probably will continue 
for the foreseeable future, in one or the other of two different 
directions, two new mainstreams. Those who are preoccupied 
with immediate causes are going into physiology in earnest, lab- 
oratory research on hormones, nerve cells, receptor organs, at the 
deepest or lowest, even molecular, level. I cannot say anything 
about this. Results are obviously flowing in, but the subject is 
complex and not my major interest and I am not competent to 
discuss it. 

4. Ethologists who are more concerned with ultimate causes 
are exploring connections or interfaces among behavior, ecology, 
and evolution. 

This has been my own preference. I may, therefore, be able 
to illustrate sonle of the positive virtues and negative drawbacks 
of the approach by citing particular cases from my own experi- 
ence. In recent years, I have been engaged in observation and 
analysis of three groups of animals, cephalopods. New World 
primates, and passerine birds (and some "near passerines" such 
as hummingbirds ) , in the field in natural or semi-natural condi- 
tions. 

Examples 

1. I was attracted to cephalopods for several reasons. They 
provide remarkable examples of evolutionary and ecological 
convergence. Beginning with a molluscan body plan, they have 
acquired large size, good eyes, large brains, and (in many spe- 
cies) active and predatory habits. They have become similar to 
many fishes and other aquatic vertebrates in these respects. (The 
convergence is discussed at length in Packard, 1972.) They 
have also evolved unique or peculiar characters such as distinc- 
tive methods of buoyancy control, color changes, and jet pro- 
pulsion. Combinations of some of these features have finally 



6 BREVIORA No. 415 

allowed them to invade the laboratory, to serv^e the neurophysi- 
ologist. I would say, without being an expert, that some of the 
operations of their central nervous systems and their handling of 
visual information must be better known than the corresponding 
processes of any other animals with the possible exception of 
man. See, for instance. Young (1964 and 1972), Wells (1962), 
and the many papers of Sutherland and his co-workers. 

In these circumstances, it is noteworthy that the social be- 
havior of cephalopods has not been studied in anything like the 
detail that might, off-hand, have been expected. (There are 
technical reasons for this comparative neglect. Most cephalopods 
do not li\'e long in captivity and/or are difficult to follow in the 
field.) Such work as has been done on the subject has been 
une\'enly distributed. The great majority of living species of the 
class can be assigned to one or the other of three diversified and 
flourishing orders. Using the terminology of Jeletzky ( 1 966 ) , 
these may be called Teuthida (including the squids), Sepiida 
(cuttlefishes and their relatives), and Octopida (octopi and 
argonauts ) . There are more or less lengthy published accounts 
of the social behavior in the laboratory of the common European 
cuttlefish. Sepia officinalis (L. Tinbergen, 1939; Holmes, 1940), 
and the common octopus. Octopus vulgaris (e.g., Packard and 
Sanders, 1971; Wells and Wells, 1972), but relatively little on 
other species, only bits and pieces on some reactions of a few 
other sepiids and octopi and several kinds of squids, mostly 
Loligo spp., in the laboratory or in the field (see references in 
Lane, 1957, and Moynihan, in press b). 

I was delighted, therefore, to encounter a species of squid, 
Sepioteuthis sepioidea, in the San Bias Island region of the At- 
lantic coast of Panama which is quite unusually easy to observe 
in the wild under natural conditions. Mr. Arcadio Rodaniche 
and I seized the opportunity to look at its social behavior. We 
have now been observing it at monthly intervals for over two 
years. 

The species occurs inshore in moderately or very shallow 
waters over turtle grass and coral. It is often extremely abun- 
dant. It is a true squid, but rather cuttlefish-like in shape, 
adapted for "hovering," and much less rapidly or continuously 
mobile than most other squids (see also Boycott, 1965). It is 
both predator, eating small fishes and crustaceans, and prey, 
being eaten by large fishes such as barracuda and snappers (and 
perhaps many other animals, including birds, Brown Pelicans, 
etc.). Individuals of the species tend to scatter singly or in pairs 



1973 EVOLUTION AND BEHAVIOR 7 

or trios to hunt more or less actively at night, but they congregate 
in large groups in the daytime to wait for prey to come to them. 
The daytime groups may be almost completely stationary for 
long (several hour) periods. Even when they are less sluggish, 
they tend to keep within rather small territories or home ranges. 
Groups are easily habituated to the presence of human observers. 
( In fact, one of the few technical problems of working with the 
species is to keep from getting too close to retain perspective and 
an overall view.) Individuals in groups are not shy about per- 
forming a variety of elaborate social reactions, including the full 
range of "courtship" and copulatory patterns, before human ob- 
serv^ers. Thus, they have provided us with a superfluity of data. 

What have been the results? 

In one sense, they have been disappointingly conventional. 
The social behavior of Sepioteuthis is essentially vertebrate-like 
in basic articulation and organization. There do not seem to be 
any general principles of molluscan behavior apart from those 
shared by most other complex animals of other phyla. But this 
squid does exhibit or illustrate a whole series of interesting special 
adaptations which may be correlated with, causally related to, 
one significant aspect of its ecology — and many of which may 
also be characteristic of other cephalopods and for the same 
reasons. 

S. sepioidea populations are highly structured. Not only do 
individuals repeatedly leave and rejoin groups, but even the 
groups are formed of sub-groups which may be separate at some 
times, with obvious hostility and territorial defense among them- 
selves, yet completely integrated at other times. There also are 
size and (presumably) age classes that assort themselves in par- 
ticular spatial arrangements according to particular temporal 
and physical circumstances. The system is both intricate and 
flexible, apparently at least as much so as those of such mam- 
malian carnivores as lions, African hunting dogs, and Spotted 
Hyenas. 

The system is mediated by signals, both ritualized (mostly 
displays) and unritualized. As far as we can tell, all the signals 
are visual. (Cephalopods seem to be deaf, and we did not 
detect, see, any indications of the use of pheromones or other 
means of olfactory communication.) The visual signals include 
postures and movements and many color changes. The number 
of ritualized patterns is quite high. The basic components of 
the ritualized repertory may not be more numerous than the 
corresponding elements in the repertories of certain birds and 



8 BREVIORA No. 415 

fishes (see Moynihan, 1970), but they can be combined and 
recombined almost endlessly. It is not uncommon to see an 
animal adopt two or three, even four or five, color patterns 
simultaneously, each color on a particular part of the body, 
while performing a series of movements, especially of the fins or 
arms, in very rapid succession. The effect is Protean. A squid 
is quite able to transmit a variety of different signals in difTerent 
directions to difTerent recei\'ers, different kinds of onlookers, all 
at nearly or completely the same times. As visual signal systems 
go, the cephalopod versions must be unique in their combinations 
of speed and diversity or multiplicity and perhaps efficiency. 

Comparison of the known patterns of Sepioteuthis, Sepia, 
Octopus, and some other cephalopods has revealed some sugges- 
ti\'e similarities and contrasts. Some displays are very distinct, 
obviously not homologous, in the different species. Others are 
very similar. Some of these are relatively simple. They may well 
have become ritualized independently in each of the phyletic 
lines. But at least four major displays are both extremely com- 
plex, exaggerated, and "unexpected," and yet strikingly similar 
in many details (of causation and function as well as form) in 
the \-arious species. These displays would appear to have be- 
come ritualized before the lines diverged from one another. As 
the divergence must have occurred well before the end of the 
Mesozoic, perhaps most probably in the Late Triassic, the pat- 
terns are not only old but also have been remarkably conservative 
during evolution. To my knowledge, they ha\e been more con- 
servative than any patterns of other groups so far recorded in the 
literature. One of the reasons whv some or all of them have been 
stable is apparent when they are compared with the other dis- 
plays of the same species that have changed more considerably 
or de\eloped more recently. The latter tend to be shown to only 
a few individuals or types of individuals. The conservative sig- 
nals, on the other hand, are designed to influence a great number 
and di\ersity of receivers, different age, size, and sex classes of 
the same species and/or individuals of other species, especially 
potential predators. This may be a general rule, applicable to 
most animals. All other things being equal, the more widely 
reflected or broadcast a signal, the more conservative it will be, 
the more narrowly reflected or broadcast, the more Ukely it is to 
be changeable in evolutionary time. 

The role of predation should be emphasized in connection 
with cephalopods. There is good evidence (see Moynihan, in 
press c) that several or many of the living members of the class 



1973 EVOLUTION AND BEHAVIOR 9 

are favorite prey of marine birds and mammals almost through- 
out the seas and oceans of the world. They must, therefore, be 
themselves enormously abundant in many areas. (Common as 
it is, Sepioteuthis has a fairly restricted distribution in the tropical 
Atlantic. Other squids must have larger populations. The total 
numbers of cephalopods in any given area are difficult to esti- 
mate precisely, as many species are nocturnal and most are diffi- 
cult to catch with the traditional gear of marine biologists, but 
the birds and mammals probably are more efficient collectors.) 
There also is evidence that the enormous biomass of cephalopods 
is di\ided among fewer "packets," i.e., species, than is that of 
their nearest competitors, the marine fishes. This could be both 
cause and consequence of their relatively greater attraction for 
predators. 

It may be assumed that many of the extinct cephalopods ex- 
hibited some or all of the demographic and ecological charac- 
teristics of their living relatives. If so, it seems likely that preda- 
tion pressure could have been the major impulse for a series of 
evolutionary events. Some of the probable steps can be listed 
briefly and crudely. The ancestors of the majority of living 
cephalopods presumably reduced, internalized, and in some cases 
lost, their originally external shells to gain greater maneuverabil- 
ity and powers of escape. This "freed" their skin for other uses, 
including the elaboration of color change mechanisms. The de- 
velopment of gregarious habits may well have been another 
(even earlier?) anti-predator adaptation (Brock and Riff en- 
burgh, 1960). The habit of living in groups puts a premium 
upon the development of complex signal systems. For vulnerable 
marine animals, a visual communication system has definite 
adxantages. (Visual signals can be turned off instantaneously 
whene\er necessary or desirable, unlike olfactory cues, and they 
are perhaps less apt to be noticed at a distance by dangerous 
receixers than are acoustic signals, especially in murky waters or 
around reefs or vegetation. And, of course, short range signals 
are perfectly adequate as long as the animals are close together. ) 
Once the skin has become speciaHzed for color changes, it prob- 
ably is not easily transformed for other purposes such as the 
development of new kinds of armor or spines. This restricts the 
choice of further anti-predator adaptations. It has already been 
mentioned that whatever displays may have to be shown to 
potential predators are conservative. As many or most of these 
patterns are also used in intraspecific encounters, they may tend 
to impede fundamental changes in the type, although certainly 



10 BREVIORA No. 415 

not the details, of the signal system as a whole. Other char- 
acters of cephalopods such as their rapid growth, relatively short 
life spans, special arrangements and care of eggs (see, for in- 
stance, Packard, op. cit., and Wells, op. cit.), and even their 
preference for reproducing only once in a lifetime, in "big bangs" 
(Gadgil and Bossert, 1970), could also be explained as responses 
to intense predation. (And the need to synchronize reproductive 
moods in a hurry, without much time for trial and error, must 
add another premium for both gregariousness and the elabora- 
tion of signals.) 

The series is an illustration of some of the ways in which 
ecology and beha\dor can interact to determine the course of 
evolution, each step opening up some possibilities and foreclosing 
others. 

2. The New World primates are a variegated family of mon- 
keys of some 11 to 13 genera and many species. I have obser\ed 
representatives of all the genera at irregular intervals over 15 
years. Some species have been observed only in captivity, at the 
field station on Barro Colorado Island and in zoos in \Vashing- 
ton, London, Paris, and Amsterdam; but many others have been 
studied at considerable length in the wild, in the central part of 
the isthmus of Panama, to the west in the province of Chiriqui, 
and to the south in the upper part of the Amazon basin, in the 
Caqueta and Putumayo regions of Colombia. 

For most biologists, the primary significance of the American 
monkeys is that they represent a wide and independent adaptix^ 
radiation. They have occupied most of the habitats available to 
primates. In this respect, they are more or less strictly equivalent 
to the two other radiations of modern primates, the (Recent and 
Pleistocene) lemuroids of Madagascar, and the so-called Old 
World monkeys and apes, the "Catarrhini," of tropical Asia and 
Africa and some adjacent areas, of which man is a specialized 
offshoot. The New World forms may thus provide a useful 
check to hypothesis and speculation about the evolution of pri- 
mates in general and man in particular. I should also like to 
claim that they are interesting in themselves. 

They range from very small (the Pigmy Marmosets of the 
genus or sub-genus Cebuella) to moderately large (the howlers, 
Alouatta, and the spider monkeys, Ateles). They show a great 
diversity of types of locomotion, from squirrel-like scrambling 
and/or vertical clinging and leaping among the marmosets and 
tamarins {Saguinus, Leontideus, Callirnico, and Callithrix in 
addition to Cebuella), through quadrupedal "springing," walk- 



1973 EVOLUTION AND BEHAVIOR 11 

ing and pacing in such forms as Saimiri and Cebus, to brachia- 
tion or semi-brachiation with the supplementary use of a pre- 
hensile tail in Ateles. (The classification and details of locomo- 
tion are discussed in Erikson, 1963, and Napier and Walker, 
1967.) At least two species of Cebus, capucinus and apella, 
come down to the ground with appreciable frequency. All or 
most of the species of other genera are thoroughly arboreal. One 
genus, Aotus, is nocturnal; the rest are diurnal. They all tend to 
be nearly omnivorous on occasion ; but most of the smaller forms, 
many of the tamarins and probably the marmosets of the genus 
Callithrix, seem to prefer insects whenever they can get them, 
while some of the larger forms are essentially herbivorous, taking 
various assortments of fruits of particular kinds and ages, as well 
as buds and leaves and even twigs and bark. At least one form, 
Cebuella, has specialized in sap-sucking. (The sap-sucking is 
described in Moynihan, in press d. The best general accounts of 
more conventional feeding habits and regimes, unfortunately lim- 
ited to the Panamanian species, are in Hladik and Hladik, 1969, 
and Hladik ^^ fl/., 1971.) 

In the course of my own studies, I have attempted to discover 
and analyze the social behavior and structures of different spe- 
cies and combinations of species, to determine how such com- 
plexes are held together (or apart as the case may be), and to 
identify some of the selective forces involved, to tie the observed 
behavior to particular aspects of ecology. The results sum- 
marized below are taken from Moynihan (in press a) ; this book 
also lists references to papers and unpublished notes of other 
workers. 

Two extreme types of intraspecific social organization can be 
recognized without much difficulty: the restricted "nuclear" 
family group and the large band. The former seems to be the 
basic social unit of Aotus, Callimico; two species of Callicebus, 
moloch and torquatus; and, in some circumstances, Pithecia 
monacha. Bands are characteristic of Pithecia melanocephala, 
Alouatta villosa, Alouatta caraya, Lagothrix, Saimiri, and some 
or all forms of Cebus and Ateles. As might be expected, there 
are intermediate conditions, complications, and exceptions. One 
type of intermediate is the "extended" family of some species of 
Saguinus, e.g., juscicollis, graellsi, midas, and Cebuella and prob- 
ably many other marmosets. Intermediates can also be flexible, 
intermittent or recurring. Small families of some species may 
join one another in some circumstances. It also is normal or 
usual for neighboring small families of most species to perform 



12 BREVIORA No. 415 

certain responses, e.g., anti-predator reactions, in common. (This 
is evidence that they do form a real social community.) Con- 
versely, large bands may split up into smaller sub-groups tempo- 
rarily, or reveal traces of sub-group organization within the 
bands without actual splitting. This appears to be most common 
in Saimiri and some form of Ateles. (The sub-groups are not 
usually families but rather cephalopod-like age and sex classes.) 

The adaptixe value of such variance is surprisingly obscure. 
It seems to be characteristic of American monkevs that there is 
little general correspondence between basic types of intraspecific 
organization and either habitat or food preferences. There are 
species that li\'e in bands and species that live in small family 
groups among the primarily or exclusively vegetarian forms. 
There also are both kinds of species, or at least forms that usually 
live in bands and forms that live in extended family groups, 
among the animals that prefer insect food when available. The 
proportions of highly to poorly gregarious species and individuals 
are much the same in many of the stages of succession from 
young second-growth scrub to mature forest in many areas. Per- 
haps even more remarkable, density of populations also appears 
to be largely irrelevant in this connection (if not for other as- 
pects of social behavior — ^ see below). Both Callicebus moloch 
and Saimira usually are abundant and concentrated where\'er 
thev occur. Thev are concentrated in different v/avs, but the 
average number of individuals per unit of time and area may be 
high in both cases. Both Aotus and Cebus albijrons can be 
described as dispersed. The albijrons occur in rather large bands, 
but the bands themselves are scattered. 

These facts would suggest that almost any type of social or- 
ganization can permit or facilitate almost any kind of exploita- 
tion of the environment within the range of niches occupied by 
American monkeys at the present time. Presumably, because 
most of them are more "generalists" than "specialists," they have 
been able to choose among alternative strategies to achieve 
similar ends. 

Much more restricted are the modalities or techniques by 
which particular social systems are maintained. The ritualized 
signal systems of these animals are not only adaptive but are 
quite obviously so, down to the finest details. They include vis- 
ual, acoustic, olfactory, and tactile patterns (Moynihan, 1967). 
Of these, the visual and acoustic seem to be usually most im- 
portant. The basic elements, the deep structures, of the repertory 
of sounds may be nearly identical in all species, with the possible 



1973 EVOLUTION AND BEHAVIOR 13 

or probable exception of Alouatta. It is not difficult to trace 
homologies among most of the vocalizations of most of the spe- 
cies, and much of the information encoded is almost uniform or 
strictly equi\'alent throughout. The forms and frequencies of 
particular patterns are, however, very different in different spe- 
cies. The differences seem to depend upon the distances over 
which sound usually need to be transmitted, the carrying proper- 
ties of the medium (the numbers and kinds of obstructions likely 
to be encountered ) , and the presence or absence of other possible 
sources of relevant information, features of the external and/or 
social circumstances and other types of signals. In fact, this 
means that both the physical forms of the patterns and the 
methods of encoding information are closely correlated with 
social structure, density of population, activity rhythms, and 
density of vegetation, as well as vulnerability to predation and 
diversity of appropriate receivers. The ritualized visual signals 
are more heterogeneous but equally easy to explain in terms of 
the same factors. 

Some New World primates are involved in, or are the foci of, 
specialized and stereotyped interspecific social reactions. Such 
reactions may take either positive or negative forms, "friendly" 
joining and following or hostile fighting or avoidance. They may 
occur among two or more species of monkeys and /or between 
monkeys and other animals such as squirrels {Sciurus granat en- 
sis, S. variegatoides, Microsciurus sp.), birds of prey such as 
Harpagus bidentatus and Leucopternis albicollis (these small 
hawks do not attack the monkeys themselves, but rather take the 
arthropods, lizards, etc., flushed by them), and even flycatchers 
{e.g., Myiozetetes, Tyrannulus, Lagatus, Elaenia, Megarynchus) . 
The combinations of positive and negative responses can be com- 
plex, and the interspecific relations of a single species may be 
different in different areas. It is possible, nevertheless, to detect 
certain general rules or trends. 

There are apparent correlations among interspecific bonds, 
feeding habits, and territorial behavior. The monkeys that are 
most likely to mingle with other species are forms such as Calli- 
cebus moloch and Alouatta villosa. They are vegetarian, taking 
items such as leaves, buds, and berries that are abundant and 
evenly distributed, and have small territories or large territories 
through which they move slowly. Individuals and groups of 
these species seldom find themselves in situations with which they 
are not thoroughly familiar or have not had time to inspect 
carefully beforehand. Conversely, the establishment of friendly 



14 BREVIORA No. 415 

interspecific bonds is characteristic of such forms as Saimiri, 
Cebus apella, and Ateles paniscus s.l. They are omnivorous or 
preferentially insectivorous or feed on plant materials that are 
dispersed or distributed in irregular clumps. They tend to have 
large territories through which they move rapidly. They must be 
precipitated into unfamiliar situations rather frequently. They 
must also, therefore, have more need of extra companions of the 
same or other species, to act as scouts or sentinels, than do spe- 
cies of more sedentary or cautious habits. 

On logical grounds, one would suppose that the various kinds 
of interspecific social behavior should be adjusted to intensities of 
competition^ as well as particular ecological facies. It would be 
expected that species that do not compete at all, or compete as 
little as may be feasible for animals that occur in the same areas, 
would usually tend to ignore one another. There are many ap- 
parent examples of such behavior among the New World pri- 
mates. It would also be expected that species that compete verv' 
strongly would tend to exclude one another from wide areas and 
entire regions. Again there are apparent examples among the 
American monkeys. 

Presumably either of these extreme types of interspecific be- 
havior can be transformed into the other in the course of time. 
It would be interesting to know the intermediate stages. Data 
from observations of the New World primates and their asso- 
ciates would suggest that the following progression (quoted from 
Moynihan, in press a) may be common as intensity of competi- 
tion increases: "When competition becomes slightly more than 
minimal, the species will tend to ignore one another in most 
circumstances but will exhibit overt and active hostility toward 
one another occasionally. (If it is only desirable or necessary to 
drive off rivals infrequently, it may be worth taking the risk of 
fighting. ) When competition is stronger, it may be advantageous 
for the competitors to join up with one another. (If you can't 
lick 'em . . .) When competition becomes stronger yet, it may 
become imperative to avoid one another. First by a\'oiding per- 
sonal encounters while still ranging over the same areas at much 

'I am employing such terms as "complete" and "competition" in the 
broadest possible sense. Two animals are considered to be competing with 
one another whenever one preoccupies, permanently or temporarily, any 
resource that would otherwise be likely to be used by the other. Among 
primates and birds, competition for preferred observation posts, singing 
perches, safe sleeping quarters, etc., may be quite as important as compe- 
tition for food. 



1973 EVOLUTION AND BEHAVIOR 15 

the same times. Then by claiming exclusive territories or by 
elaborating some form of temporal segregation. (Segregation by 
differential timing may have peculiar advantages, but it can only 
work when the species involved are not too numerous.) From 
the claiming of exclusive territories, there may be no more than 
a small step to complete allopatry. It seems very probable that 
the process can also go in the opposite direction, through the 
same stages but in reverse order, and that the direction of 
change can be reversed repeatedly, with or without reaching the 
extreme conditions at either end." 

3. Most of my recent work on birds has been conducted in the 
Andes. 

The higher reaches of these mountains provide a wealth of 
material for students of biogeography. They include a large 
series of habitats and biotas that differ from those of the sur- 
rounding lowlands in several respects {e.g., temperature, endemic 
species). The northern part of the Andes is extremely complex 
in structure, with separate cordilleras, chains of mountains, and 
a scattering of single peaks and massifs. The central and south- 
ern parts are simpler, more unified in general or overall form, 
but still varied in details of terrain and cHmate. As a result, 
many of the higher altitude habitats and biotas are distributed 
in patches, partly or wholly isolated from one another. They 
are essentially ijisular. They differ from oceanic islands, how- 
ever, in not being impoverished. The higher Andes have "com- 
plete" or "balanced" floras and faunas. They are inhabited by 
many kinds of organisms which have occupied most of the 
obvious niches or ecological roles, exploited most of the available 
opportunities. They are, therefore, ideal for analyses of some 
aspects of insular evolution. The effects of isolation and adapta- 
tions to facilitate or impede invasions can be studied per se, 
quite apart from the possible distortions of "accidental" barriers 
or "sweepstake" phenomena. 

I have concentrated upon interspecific behavior among two 
groups of species of a particular "life zone." Observations were 
begun in 1959 and have continued off and on until the present. 
The results are being analyzed and written up. Many details 
remain to be settled, but the general sense of the bulk of the 
data is clear. 

The life zone is the one that Chapman (1917 and 1926) 
called "humid temperate." The term is perhaps misleading — 
"cold humid tropical" might be more suitable (see comments in 
Moynihan, 1971). The zone is best developed around 2800- 



16 BREVIORA No. 415 

3300 m in most areas. Its natural \egetation would be more or 
less dense forest and "alpine" scrub (Weber, 1969). Some of 
this survi\es apparently intact. The rest has been replaced by 
secondary bush, gardens, hedges, crop fields, pastures, etc. For- 
tunately, substantial numbers of the native birds have been able 
to occupy and even flourish in some (the lusher) of these man- 
made habitats. They are still easily observable. The distribution 
of the zone is eccentric within the Andes. It must cover almost 
the whole of the northern Andes at appropriate elevations, i.e., 
it is scattered among islands, most of which are small, a few of 
which are large but long and narrow. It is much broader and 
more nearly continuous in the central Andes, in all or most of 
central Ecuador and northern Peru. It becomes progressi\'ely 
narrower toward the south, even though the Andes themselves 
remain broad. The apparent discrepancy is due both to the relief 
of the mountains and the nature of the prevailing wind systems 
(briefly summarized in Murphy, 1936). Rain falls off at an 
unequal rate. The principal southern extension of the zone is 
along the eastern slope of the chain, down into central Bolivia. 
It is dissected by the deep valleys of rivers flowing to the Ama- 
zon. In effect, the southern extremities are a series of narrowly 
linked narrow peninsulas. 

My own observations have ranged from the Sierra de Merida 
in Venezuela and the Sierra Nevada de Santa Marta in northern 
Colombia down through central and southern Colombia, Ecua- 
dor, and Peru to northern Bolivia, the Yungas of La Paz, at 
altitudes between 2400 and 3700 m. This is nearly the full 
length of the cold humid tropical zone, with the addition of 
some fringe areas of adjacent zones. 

One of the groups of species studied could be called the 
''Diglossa cluster." It includes six species or superspecies of the 
genus, flower-piercers, which may be called carbonaria, lafres- 
nayei, albilatera, baritula, cyanea, and coerulescens (this is the 
nomenclautre and classification of Zimmer, 1929; HeUmayr, 
1935; and de Schauensee, 1970 — Vuilleumier, 1969, suggests 
a slightly different arrangement, and other refinements are con- 
ceivable), as well as the conebill Conirostrum cinereum and 
some hummingbirds such as Colibri coruscans, Aglaeactes cupri- 
pennis, and Ramphoynicron microrhynchufn. All these birds are 
nectarivorous to a greater or lesser extent. 

The other group includes many more species of different sub- 
families, families, and at least one more order. For want of a 
better name, I shall call it the "tanager cluster." It includes a 



1973 EVOLUTION AND BEHAVIOR 17 

variety of closely related montane tanagers, mostly black and 
blue with touches of yellow, buff, or red, of such genera as 
Anisognathus, Buthraupis, and Iridosornis (and also the "Plush- 
capped Finch," Catamhlyrhynchus, hardly distinguishable from 
Iridosornis in appearance or habitus in the field^) ; other tanagers 
of rather different stocks [e.g., Chlorospingus, Cnemoscopus, 
Hemispingus, Chlorornis) ; finches of the genus Atlapetes; some 
other conebills (especially Conirostrum sitticolor — see Moyni- 
han, 1968) ; warblers of the very different genera Myioborus and 
Basileuterus'- ; a few flycatchers {e.g., Uromyias and Megacer- 
cuius spp.); the occasional hummingbird {e.g., Ensifera and 
Coeligena) ; a few woodpeckers [e.g., Piculus rivolii in Vene- 
zuela) ; and many furnariids and dendrocolaptids [Margarornis, 
Synallaxis, Cranioleuca, etc.). And at least one squirrel in the 
western cordillera of Colombia [Sciurus granatensis again!). 
The association includes frugivores (different species taking dif- 
ferent fruits ) , insectivores ( catching different insects in different 
ways), a new nectarivores, and many types with very mixed 
diets. Different species also prefer different levels of vegetation, 
from the highest tree-tops down to the ground. 

The chief peculiarity of both clusters, the one that drew my 
attention, is that their members show pronounced intraspecific 
geographic variation in their interspecific behavior. More pre- 
cisely, individuals of a single species or superspecies react very 
differently to individuals of other species in different regions 
(often the same other species in each of the regions). The vari- 
ation affects different types of interspecific behavior in the two 
clusters, hostility in the Diglossa association and "friendliness" 
in the tanager association, but the trends are roughly parallel in 
both, although inverse and complicated by certain exceptions. 
The exceptions themselves are sometimes revealing. 

The situation is roughly as follows : 

^The classification of the "New World nine-primaried songbirds" is in 
need of further revision. Some of the supposed families and subfamilies of 
the group appear to be polyphyletic in origin. Some of the genera cmrently 
assigned to one family may be more closely related, phylogenetically, to some 
of the genera assigned to other families than to other genera assigned to the 
same family. Terms such as "warbler," "tanager," and "finch" are little more 
than short-hand descriptive labels for certain ecological categories. 

^In the case of these Andean birds, it seems probable that a revised scheme 
would place the Plush-capped Finch in the same tribe as the tanagers it so 
much resembles, and also link Basileuterus to Hemispingus rather than to 
Myioborus. 



18 BREVIORA No. 415 

Many members of the tanager cluster extend throughout all or 
most of the cold humid tropical zone. All show tendencies to 
form or join mixed species flocks in some areas and regions (this 
is the prescriptive reason why they have been assigned to the 
cluster). In general, individuals of the same species behave in 
similar ways in the northern and southern extremities of the zone, 
but very differently in the central part. They show a high degree 
of interspecific gregariousness in the western and central Cordil- 
leras of Colombia (the western cordillera is alwavs extremely 
northern, "far out," in the behavior of its inhabitants — see also 
below). In these regions, the birds occur in mixed flocks most 
of the time, and most of the flocks are large, cohesive, complex 
in structure, and stable (maintained for hours on end and often 
re-formed on successive days). In the eastern cordillera of Co- 
lombia and the Sierra de Merida, the birds still show a con- 
siderable amount of interspecific gregariousness, but mixed flocks 
are formed somewhat less frequently and tend to be smaller, 
looser, and simpler in structure on the average (the decline may 
be more evident in the eastern cordillera than in Venezuela ) . 
In central Ecuador and central and northern Peru, interspecific 
gregariousness is slight. In fact, quite absent in some localities. 
Even when and where mixed flocks are formed, they are always 
small and simple, and usually loose and sustained for only a few 
minutes. The trend is reversed in southern Peru and northern 
Bolivia. Mixed flocks become larger, more stable, cohesive, and 
complex again ( rather more so in Bolivia than in Peru, but never 
as much so as in the western cordillera of Colombia ) . 

It is obvious that the development of flocking depends upon 
several factors. There are positive correlations among densities 
of populations, thickness of vegetation, and frequency and elab- 
oration of interspecific gregariousness within regions. But these 
cannot account for the whole of the major geographic trends. 
They do not explain the exceptions. There must be something 
else involved. This would appear to be an "invasion" or "fron- 
tier" effect. Interspecific gregariousness seems to go up with 
exposure to, or anticipated number of, invasions from or into 
other regions of the same life zone or an adjacent zone, the warm 
or hot humid zone of lower elevations. 

The western cordillera of Colombia is the least continuous of 
the major chains of the Andes. Its patches of cold humid habi- 
tats are comparatively small. The populations of these small 
islands must include a relatively very high proportion of indi- 
viduals near the frontiers of their patches and a low proportion 



1973 EVOLUTION AND BEHAVIOR 19 

of individuals at the centers of patches, away from the frontiers. 
The same must be true of the populations of the narrow penin- 
sulas of the zone in the far south. Birds on the frontiers must 
encounter strays from other zones and stray into other zones more 
often than do birds from the centers. It would seem that this is 
one of the causes of interspecific gregariousness. The evidence 
is somewhat restricted, but I think convincing. In central Ecua- 
dor, I worked along one transect from the top edge of cold 
humid forest and scrub down into the upper reaches of warm 
humid forest. Interspecific gregariousness is essentially nil in the 
higher part of the cold humid zone, but increases abruptly at 
the exact point where occasional strays from the warmer zone 
begin to appear with some appreciable, if still low, frequency. 
(The increase is "intrinsic." It is always apparent, whether or 
not strays are present at the moment.) The remarkably high 
degree of gregariousness of the birds of the central cordillera of 
Colombia, higher than would be expected of its not particularly 
northern or isolated position, may also be correlated with the fact 
that it is exposed to invasions from the nearby chains on either 
side as well as from the immediately adjacent lowlands. 

What is the functional significance of this apparent connection 
of interspecific gregariousness with frontiers, strays, and inva- 
sions? The advantages of mixed flocking from the point of view 
of a straying bird in an unfamiliar area are obvious, and much 
the same as in the monkeys cited above. By associating with 
experienced local individuals, a stray may be able to discover 
and identify food and/or danger relatively rapidly. The ad- 
vantages for the "hosts" of a stranger are more problematical. 
Of course, they are acquiring a companion who may be of use 
in various ways. They are also encouraging or tolerating a com- 
petitor. Perhaps one of the reasons that they do so is that they 
may become strangers in their turns. Some of them must also 
stray into adjacent life zones, where they will also need the help 
of local inhabitants. It may be diflficult for an animal to join and 
follow strangers without also developing some tendency to allow 
itself to be joined and followed by strangers. (The roles of joiner 
and joined are easily distinguishable in some areas such as parts 
of Panama — see, for instance, Moynihan, 1962a — but they 
are less clearly distinct in these Andean flocks. In any case, both 
roles often reflect similar states of mind.) It seems to be char- 
acteristic of most animals that they cannot, at least do not, sup- 
port very great qualitative differences in kind of social responses. 
A species that is comparatively aggressive in one class of social 



20 BREVIORA No. 415 

encounters also tends to be aggressive in other encounters. Sim- 
ilarly, a species that is gregarious in some circumstances usually 
tends to be gregarious in other circumstances. 

This "extrapolation" may have been favored in Andean birds 
because the boundaries of their life zones have been fluctuating, 
repeatedly shifting back and forth in recent geological histor\' 
(see Simpson-Vuilleumier, 1971 ). Many of the birds of the cold 
humid zone must have had to invade new areas, and cope with 
invaders from other areas, again and again in response to secular 
climatic changes, quite apart from or in addition to the normal 
stravinsf that would have occurred even if the frontiers had been 
fixed and permanent. 

The species of the Diglossa cluster show another contrast be- 
tween individuals of the central part of the cold humid zone and 
those of the northern and southern extremities of the zone. Some 
aspects of their interactions in central Ecuador have been de- 
scribed in Moynihan (1963). Each of the local species has its 
own, partly unique, series of ecological preferences, but the 
ranges of most species are broadly overlapping. The territories 
of indi\'iduals of different species are often completely overlap- 
ping. Indi\iduals of different species may use the same perches, 
move along the same pathways, feed in the same places on the 
same types of foods. But they almost never do so simultaneously. 
They are almost always kept a few meters apart, at any gi\'en 
instant of time, by some avoidance mechanisms. There is also 
mutual inhibition of "Song" among individuals of different 
species of Diglossa and Conirostrum cinereum, although not 
among individuals of the same species. The whole thing can be 
summed up as rigid and continuous social segregation. In the 
western cordillera of Colombia and in northern Bolivia, on the 
other hand, many of the species are separated microgeographi- 
cally, each largely or completely confined to a particular facies 
of habitat slightly different from the facies of all or most of the 
others. This may be due to fighting. On the rare occasions when 
individuals of different species that are usually separated do 
happen to come together, they usually fight, actually attack, one 
another. There is no visible avoidance mechanism. Thus, the 
microgreographical segregation may be encouraged or imposed 
by reactions among individuals but it is not continuously social 
in the same wav as in central Ecuador. Conditions are more or 
less intermediate in the Sierra de Merida, the eastern and central 
Cordilleras of Colombia, and many areas of Peru, with all com- 



1973 EVOLUTION AND BEHAVIOR 21 

binations of partial overlaps, incomplete avoidance and inhibi- 
tion, and more frequent and prolonged overt disputing. 

The variations of the birds of the Diglossa cluster are also 
correlated with factors such as density of vegetation and inter- 
specific competition. They do not, however, include frontier 
effects. They would seem to be more concerned with size of local 
populations and competition within regions rather than invasions 
by strays from without {Diglossa individuals are very sedentary). 
Indi\iduals of the small northern and southern populations may 
hope to fight off all or most of their not very numerous com- 
petitors with relative ease. Individuals of the larger central pop- 
ulation probably could not fight off their more numerous com- 
petitors without exhausting themselves in the process or taking 
unacceptable risks of physical injury. 

It will be noticed that different adaptations for coping with 
interspecific competition may tend to produce different diversity 
gradients in the two assciations. In the Diglossa cluster, species 
dixersity at any given point is least at the extremities and prob- 
ablv CTeatest at the center of the cold humid zone. In the 
tanager cluster, species diversity must often be greatest at par- 
ticular points in the extremities and least at the center. 

Comments 

The sorts of work cited above are perhaps typical of a con- 
temporary approach to ethology. I should hope that they would 
suggest certain conclusions about studies of behavior and the 
relationships of such studies to analyses of evolutionary processes. 

Beginning with the purely ethological aspects, it seems evident 
that causation is the crucial problem. Studies of ultimate causes, 
natural selection, seem to be proceeding fairly well. At least, 
there are no theoretical or basic methodological difficulties in- 
volved. Studies of proximate causes, physiology, may also be 
making progress, perhaps more rapid and exciting progress. But 
there is very little contact between the two lines of investigation, 
least of all when vertebrates provide the working material. 
Doubtless, there will be a new and sophisticated synthesis of the 
two approaches at some date in the future. I do not expect to 
see it in my own (research) life time. I should also imagine 
that, when it comes, it will be largely due to an expansion of 
concern and efforts by physiologists. They would seem to be in 
a better practical position to develop the necessary techniques 
than are the field-oriented "natural historians." 



22 BREVIORA No. 415 

Meanwhile, there is still a lot that the ethologist can do for 
for the evolutionist. 

Beha\'ioral information can help to illuminate the evolution of 
particular groups of animals. They have, for instance, increased 
our knowledge of the phylogenies of many vertebrates such as 
ducks and geese (Lorenz, 1941; Delacour and Mayr, 1945; 
Johnsgard, 1965), gulls and terns and their relatives {e.g., 
Moynihan, 1962b), and cichlid fishes [e.g., Baerends and Baer- 
ends, op. cit.). As taxonomic characters, however, behavior 
patterns are no more and no less valuable than any other char- 
acters. They may be more useful in some cases than in others, 
more useful than other features in some groups, less useful in 
other groups. They should continue to be considered, to be taken 
fully into account, in systematic studies. But I would suggest that 
they can make a more significant contribution to the analysis of 
evolution by providing concrete, immediate, information to help 
explain certain ecological phenomena, developments, and inter- 
actions which are themselves among the causes of evolutionary 
changes. 

A substantial proportion of current and recent ecological re- 
search has been devoted to such matters as competition, co- 
existence, partitioning of resources, invasions of new areas and 
habitats, replacement, and extinction (see the works of Hutchin- 
son, Mac Arthur, Wilson, and others). There has been a stimu- 
lating sequence of papers with models and diagrams, mathe- 
matical formulae and other elaborations of symbolic logic, to 
describe and summarize the results of interactions among indi- 
viduals and species at present, as they probably were in the past, 
and as they may be expected to be in the future and always. 
What seems to me to have been lacking in many or most of these 
discussions is attention to some of the details of the ongoing 
processes as well as their end products, how and why they actu- 
ally work in fact and in nature, the mechanics by which the final 
results are achieved. A great many questions have been left 
hanging in air. What do individuals of the same or different 
species really do when they come face-to-face with one another? 
Or when they occur in the same areas without necessarily en- 
countering one another directly? What are the forms of compe- 
tition? Who moves where, and why and when? How are spe- 
cific resources found, used, preoccupied, defended? What are 
the relevant clues? How does replacement occur on a day-to- 
day or year-to-year time scale? What are the adaptations which 
permit or facilitate supplants and invasions? How are these 



1973 EVOLUTION AND BEHAVIOR 23 

adaptations used in life and why are they effective? Why are 
some adaptations more effective than others that could have 
been used instead? Is there any consistent relation between size 
of area inhabited and probabiUty of success? Are there some 
species that are really specialists in competition? If so, why? 
And how do they manage it? 

These are the kinds of questions which behaviorists should be 
able to answer, in whole or in part. I think that many behavior- 
ists are trying to find the answers now. I hope and expect that 
they will continue to do so. 

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26 BREVIORA No. 415 

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1973 EVOLUTION AND BEHAVIOR 27 
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28 BREVIORA No. 415 

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1973 EVOLUTION AND BEHAVIOR 29 

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. 'OO:: -m 



Kt-! 



• • •- . 



•.■•'•..■•. 



B R E V I O R A 



MU0. COMP. ZOOL 

Museum of ^fWffi^arative Zoology 

Cambridge, Mass. ^^[^^j^qber 1973 Number 416 

UNiVfiRSlTYi 
MUSEUMS AND BIOLOGICAL LABORATORIES 

Ernst Mayr 

When Professor Crompton invited me to give a short after- 
dinner address on the occasion of the opening of the wing, he 
added that he wanted to publish it. This posed a challenge to 
me to come up with something that is worth being printed. 
However, I consider this invitation less of a challenge than a 
welcome opportunity to present some thoughts on museums and 
their role in science. 

The speakers this afternoon have rightly emphasized that the 
opening of the Museum's laboratory wing is a milestone in the 
history of the MCZ. It is an occasion to look back to the days 
of its founding and an occasion to look forward to its future. 
It is also an occasion to ask some searching questions. For 
instance, someone unacquainted with biology and intolerant of 
anything but his own hobbyhorse, might ask, "Why do we still 
need natural history museums?" Such a question is quite legiti- 
mate, for I am a strong believer in the principle that the 
legitimacy and continuing value of traditional rituals and insti- 
tutions should be challenged from time to time. How, then, 
would we answer this question? 

The role of museums in science, and their image in our so- 
ciety, is changing from decade to decade. When natural history 
was revived during the Renaissance and during the 17th and 
18th centuries, it expressed at first man's wonder and bewilder- 
ment at the enormous variety of life. This "diversity of nature" 
has been a key concept in man's world picture from the days 
when the Lord told Adam to give names to all the creatures in 
the field to the present day when species diversity is one of the 
central themes in the work of the ecologists. 

The rich treasures brought back from exotic countries in the 
18th and 19th centuries by voyages and expeditions, combined 



.--■*■ 



2 BREVIORA No. 416 

with the steady rise of a more and more scientific attitude in 
Western man, resulted in a changed concept of organic diversity. 
No longer was it merely a source of wonder but naturalists 
began to raise questions concerning the reasons for the existence 
of so many and such strange organisms and about the meaning 
of their peculiar distribution in Asia, Africa, the Americas, and 
Australia. 

I am not claiming that naturalists were always interested only 
in the most lofty generalizations because there was hardly a 
naturalist who was not also infected by that strange virus called 
the collector's fever. Perhaps no one was more affected by this 
disease than the founder of the MCZ, Louis Agassiz, who cheer- 
fully pawned ever\thing he owned in order to acquire more 
specimens. Indeed, it is said that only a few decades ago this 
Museum still had unopened boxes of collections from Louis 
Agassiz's days. 

These collections, however, were not merely the useless gather- 
ings of pack rats. It was their study which helped bring about 
a conceptual revolution — the establishment by Darwin of the 
theory of evolution, to a considerable extent based on Darwin's 
own researches during the voyage of the "Beagle" and the sub- 
sequent working out of his collections. And the proposal of the 
theory of evolution was only one of several such conceptual 
revolutions in the history of natural history. 

The diversity of nature has been considered, ever since Dar- 
win, a documentation of the course of evolution. Research in 
the pathway of evolution indeed turned out to be an incredibly 
rich gold mine. And it was the museums that established and 
maintained leadership in this type of research. The historians of 
biology have clearly determined that the crucial advances in the 
modern interpretation of species, of the process of speciation, and 
of the problems of adaptation were made by systematists. 

One of the greatest conceptual revolutions in biology, the 
replacement of essentialism by population thinking, was intro- 
duced into biology by museum systematists. From systematics 
it was brought into genetics by workers like Chetverikov, Timo- 
feeff-Ressovsky, Dobzhansky, Sumner, and Edgar Anderson, all 
of whom had either been trained as systematists or had worked 
closely with systematists. 

Again and again the students in special branches of biology 
such as biogeography have gone back to systematics for material 
and for novel ideas. 

The speakers this afternoon have documented sufficiently how 



1973 MUSEUMS AND LABORATORIES 3 

important museums and systematics are. But this raises another 
question, which is: "Why is systematics so important?" And this 
leads right on to the further question of the position of syste- 
matics in biology as a whole. I pointed out a dozen years ago 
that, in spite of all of its unitary characteristics, biology really 
has two major divisions; indeed, one can speak of two biologies. 
In the first one, functional biology, "How?" questions are the 
important ones. This is the biology that deals with physiological 
mechanisms, developmental mechanisms, metabolic pathways, 
and with the chemical and physical basis of all aspects of life. 
To use modern technical language, this part of biology ultimately 
deals both with the translation (decoding) of genetic programs 
into components of the phenotype and with their subsequent 
functioning. This type of biology played a decisive role in dis- 
proving conclusively all vitalistic notions and in establishing firmly 
that nothing happens in organisms that is in conflict with the 
laws of chemistry and physics. This is the biology which inter- 
prets all cellular and developmental processes, both the normal 
ones and such abnormal ones as the origin of cancer. 

The other biology is interested in the genetic programs them- 
selves, dealing with their origin and evolutionary change. It 
continuously asks "Why?" questions, for instance: 

Why is there such a diversity of animal and plant life? 

Why are there two sexes in most species of organisms? 

Why is the old faunal element of South America seemingly 
related to that of Africa while the new one is related to that of 
North America? 

Why are the faunas of some areas rich in species and those of 
others poor? 

Why are certain organisms very similar to each other, while 
others are utterly different? 

In the last analysis, all questions in this part of biology are 
evolutionary questions, and museum-based collections are ulti- 
mately needed to find the facts for posing and answering all of 
these questions. 

At this point some of the more perceptive members of this 
audience will think that I have painted myself into a corner. 
Why, they will say, do you need a laboratory wing when the 
method of systematic and evolutionary biology is the comparative 
method, based on observations? Why do you have to perform 
experiments? 

The explanation for the seeming contradiction is that I have 
told only part of the story. Systematics, as it was defined by 



4 BREVIORA No. 416 

G. G. Simpson, "is the scientific study of the kinds and diversity 
of organisms and of any and all relationships among them.'' 

This definition has two consequences: First, it means that 
the systematist also must ask "How?" questions, like "How do 
species multiply?" or "How does an evolutionary line acquire 
new adaptations?", or "How did the phyletic line leading to 
Man emerge from the anthropoid condition?". 

All these evolutionary questions deal with the historv' of 
changes, and, most importantly, with the causation of changes. 
Translated into Darwinian language, each of the questions I 
have just posed can also be stated in the following terms: 

"What were the selection pressures responsible for causing the 
stated evolutionary changes?" 

Not only is it often necessary to make use of experiments to 
answer this type of question, but, more importantly, many of 
such questions cannot be answered — or at least not completely 
— simply by the study of preserved material. 

Since the investigation of diversity includes the study of rela- 
tionships, organisms must be studied alive and in the field. In 
the last 150 years there has hardly been an outstanding sys- 
tematist Vv^ho was not, at the same time, an outstanding field 
naturalist, and who could not have been called, with equal 
justification, an ecologist or a student of behavior. This is, by 
no means, a recent development. Re-reading recently Louis 
Agassiz's "Essay on Classification," published in 1857, I was 
astonished to find what stress he placed on the study of the 
"habits of animals," as he put it. 

"Without a thorough knowledge of the habits of animals," 
he said, "it will never be possible to determine what species are 
and what not." Today we would call this a biological species 
concept. He goes on to say that we want to find out ''how far 
animals related by their structure are similar in their habits, and 
how far these habits are the expression of their structure." He 
continues, "How interesting would be a comparative study of 
the mode of life of closely allied species." Indeed, Agassiz pro- 
poses a program of study which is virtually identical with that 
of the founders of ethology more than 50 years later: "The more 
I learn about the resemblances between species of the same 
genus and of the same family . . . the more am I struck with the 
similarity in the very movements, the general habits, and even in 
the intonation of the voices of animals belonging to the same 
family ... a minute study of these habits, of these mo\ements. 



1973 MUSEUMS AND LABORATORIES 5 

of the \oice of animals cannot fail, therefore, to throw additional 
light upon their affinities." 

An interest in the behavior of animals is still a tradition in 
the MCZ, more than 100 years later. Half of my Ph.D. students 
in the last 20 years, for example, did their theses on problems of 
beha\ior. One of the outstanding characteristics of the so-called 
new systematics is the concern with the attributes of the living 
animal. Variation, adaptation, speciation, and evolutionary 
change cannot be fully understood unless the field work is sup- 
plemented by experimental research in population genetics, the 
analysis of protein and chromosomal variation in populations, 
the study of the relations between adaptation and functional 
morphology, to give merely a few examples. Laboratories for 
such studies are a major component of the new wing. Environ- 
mental physiology, another aspect of animal adaptation of great 
interest to the evolutionist, is being studied at the Countway 
Laboratories of the Concord Field Station. 

The outside world has been largely oblivious to these develop- 
ments and, I am sorry to say, unfortunately so have also many 
svstematists. For the modern svstematist, however, all this seems 
to be a perfectly natural development. Anyone who has read 
books Hke Huxley's New Systematics (1940) or my own Sys- 
tematics and the Origin of Species (1942) knows to what an 
extent all these mentioned activities have been part of systematics 
for at least 30 years. The new wing gives us an opportunity to 
help correct the false image about museums which is still widely 
held, and replace it by the new concept, the beginnings of which 
were already outlined by Louis Agassiz 1 1 6 years ago. 

The new wing signals to the outside world that the MCZ 
is not merely a repository of collections but a biological research 
institute that differs from the other laboratories in the Biological 
Laboratories only in the nature of the subject matter. While 
the emphasis in much of the Biological Laboratories is on cells 
and the molecular constituents of cells, the major emphasis in 
the MCZ is on the whole organism, on the diversity of organisms 
and on their evolution. Since closest contact between the two 
groups of investigators is of the utmost mutual benefit to both of 
them, the organization of the Department of Biology was modi- 
fied in recent years in order to integrate the staffs of the two 
groups. Research and teaching are the objectives of both of 
them. 

In this day and age science is no longer conducted merely for 
its own sake. Science is no longer the tenant of an ivory-tower. 



6 BREvioRA No. 416 

Without wanting to minimize in any way the indispensabihty of 
basic science, we now realize that the scientist also has social 
obligations. When optimistically inclined he will say that he is 
helping to build a better world; when pessimistically inclined 
he will say he is trying to prevent a further deterioration of this 
world. 

But he cannot do this unless he has a sound understanding of 
Man and of the world in which he lives. And it is precisely the 
study of diversity and of evolutionary history which has made a 
major contribution toward the development of a new image of 
Man. 

In the pre-Darwinian literature, and also, in much of certain 
types of contemporar)^ literature, man is conceived as a static 
being, created within an equally static nature that is subservient 
to him. Ever since Darwin this concept has increasingly been 
replaced by a new image, an image of an evolved and still 
evolving man, part of the evolutionar)' stream of the whole living 
world. And this new image, the direct product of evolutionary 
and natural history studies, is of critical importance, not only 
for our personal concept of the world in which we live, but also 
for such quite practical issues as man's relation to the environ- 
ment, to the natural resources, and indeed even to the inter- 
action among men. 

It is about time we realize that the future of mankind is not 
something "written in the stars," something controlled by ex- 
ternal forces, but that it is we humans ourselves who hold the 
fate of our species in our hands. We now have a fairly good idea 
what the major ills of mankind are and it has become quite 
clear that only a few of them are susceptible to purely techno- 
logical solutions. Instead, most of them are of a beha\'ioral- 
sociological nature and require a change in our value systems, 
a change one is not likely to accept unless one has a far better 
understanding of nature, of the dynamics of populations, of the 
biological basis of behavior, and of other components of the 
biology of organisms, than most of those have who are responsi- 
ble for policy decisions. 

It will require a deeper understanding of the mentioned prob- 
lems and it will require massive education based on the findings 
that emerge from the type of researches that we are planning. 
During the planning of the wing we sometimes referred to it as 
a new "center for environmental and behavioral biology." Al- 
though this title was not officially adopted, it is indeed an apt 



1973 MUSEUMS AND LABORATORIES 7 

description of the focus of attention of the investigators in our 
new facihty. 

There may be some who have not kept up with recent devel- 
opments in biology and who might consider it far-fetched to 
claim that the mentioned problems fall within the area of 
interest of systematics. And yet with systematics defined as the 
science of biological diversity and with the organism defined as 
something living and not merely a preserved specimen, a solid 
chain of links is formed from the systematics of Linnaeus through 
that of a Louis Agassiz to that of the modern evolutionary sys- 
tematist and population biologist. 

I add my vote of thanks to those who have made the creation 
of this new center of environmental and behavioral biology pos- 
sible. I predict that it will have an impact on our knowledge 
and our thinking that will reach to the far corners of the earth. 



^ -(V ^\(J rr) 6 



B KMJU R A 



LIBRARY 

Vliiseiini of Comparative Zoology 

JAN 7 m 



JAN 

US ISSN 0006-9698 



HARVARD ~ ~Z 

Cambridge, MASgj|^|^8_DjjMyBER 1973 Number 417 

A NEW SPECIES OF CYRTODACTYLUS 

(GEGKONIDAE) FROM NEW GUINEA 

WITH A KEY TO SPECIES FROM THE ISLAND 

Walter C. Brown^ 

AND 

Fred Parker- 
Abstract. A new species of Cyrtodactylus from New Guinea is described. 
The type locality is Derongo at an altitude of 1300 feet on the Alice River 
tributary system to the upper Fly River, in western Papua, New Guinea. 
A key to the species of Cyrtodactylus which have been recorded from New 
Guinea is also provided (see de Rooij, 1915, for descriptions of most of the 
species) . 

Introduction 

Of the nine species of Cyrtodactylus previously recorded from 
New Guinea, known ranges of at least two (C. sermowaiensis 
and vankampeni) are restricted to one or two localities. The 
species described in the present paper may also exhibit a limited 
range, for although the junior author has collected extensively 
in papuan New Guinea for several years, no specimens have 
been collected thus far outside of the type locality in the head- 
waters of the Fly River. 

Inger (1958) calls attention to the usefulness of the pattern of 
the enlarged scales in the preanal region and on the under sur- 
face of the thighs as characteristics for distinguishing species of 
Cyrtodactylus, and uses it in the key to the species from the 
Philippines and Borneo. We have found these characters sim- 

^Califomia Academy of Sciences and Menlo College, Menlo Park, California 
94025 

^P.O. Box 52, Daru, Papua, New Guinea 



2 BREVIORA No. 417 

ilarly useful in separating most of the New Guinea species. We 
have not had the opportunity to examine specimens of C. novae- 
guineae. 

Cyrtodactylus derongo new species 

Holotype. Museum of Comparative Zoology Rl 26205, an 
adult female, collected by Fred Parker in the Derongo area at 
an ele\'ation of 1300 feet, Alice River system, tributary to the 
upper Fly River, Papua, New Guinea, 8 April 1969. 

Paratypes. Museum of Comparative Zoologv Rl 26203, 
126204,' and 126206, Papua New Guinea Museum R995, and 
American Museum of Natural Historv 103910, same data as the 
holotype. 

Diagnosis. A Cyrtodactylus with small scales on postero- 
ventral surface of thighs meeting the enlarged scales of antero- 
ventral surface at a sharp boundary; the rows of enlarged 
femoral scales forming a continuous series with preanal rows; 
enlarged preanal scales posterior to the pore series absent; dorsal 
ground color dark brown with very faint darker blotches en- 
closing irregular rows of large, white tubercles ( Fig. 1 ) . 

Description. A moderately large Cyrtodactylus; four adult 
females measure 105-112 mm snout-vent length, one specimen 
81 mm in snout-vent length is immature; head about one and 
one-half times its breadth; eye, large, its diameter about one- 
third of the length of the head and about equal to its distance 
from, the nostril; diameter of ear opening less than half its dis- 
tance from the eye; head covered with granules, very small 
posteriorly and somewhat larger anteriorly; scattered, moderate- 
sized, pointed tubercles as far anterior as the interorbital region ; 
rostral large, rectangular, its breadth about 60 percent of its 
length, nostril bordered by the rostral, supranasal, first labial 
and 3 small shields; upper labials 11 or 12; lower labials 1 1 to 
13; supranasals large, separated by 1 or 2 scales; one large pair 
of postmcntals in contact posteriorly for about half their length; 
distinct lateral fold lacking, but its normal position marked by a 
row of flattish tubercles separated from one another by several 
smaller scales; in the mid-body region, 20 irregular lines of dorsal 
tubercles between the aforementioned rows of flattish scales; 15 
to 1 8 rows in the axillary region ; some of the tubercles are white 
and tend to form widely separated irregular transverse lines, 8 
to 10 between the nape and the hind limbs; undersurface of 



1973 



CYRTODACTYLUS DERONGO 




Figure 1. Dorsal view of Cyrtodactylus derongo, MCZ 126205, type specimen. 



4 BREVIORA No. 417 

head with small granules; venter with about 46 to 48 rows of 
scales at the mid-body between the ventrolateral rows of tuber- 
cles, small and granular laterally, but merging gradually with 
the large cycloid scales of the mid-venter; the large preanal-pore 
scales in a \'ery shallow "/\" continuous with a row of femoral- 
pore scales that are gradually reduced in size along the femur; 
those anterior to the pore row somewhat enlarged, flattish scales 
on both the thighs and the preanal region, the latter merging with 
those of the \enter; posteriorly the pore series is met abruptly by 
small granular scales in both the preanal and femoral regions; 
24 to 26 rows of lamellae and scales beneath the fourth toe; 
tail only slightly depressed, with square or rectangular plates 
toe; tail only slightly depressed, with square or rectangular plates 
on the \entral surface and with everv fourth or fifth scale dis- 
tinctlv enlar2:ed. 

Snout-\'ent length of holotype 105 mm. 

Color ( in preservative ) . The dorsum is dark reddish brown 
with 9 or 1 very faint series of darker blotches each enclosing 
two to several large white tubercles; the latter tend to form very 
irregular, widely separated, transverse rows; in the inter\'ening 
areas the tubercles are dark or have a faint whitish tip; scat- 
tered white tubercles also occur on the posterior part of the head, 
the dorsal surfaces of the limbs and the base of the tail; venter 
lighter brown, most dilute on the head and throat, each scale 
marked by a xarying number of small brown spots and flecks. 
In life, the dorsal ground color is dark purplish brown; the 
venter is paler and more translucent. The iris is deep brown. 

Habitat note. The specimens of Cyrtodactylus derongo were 
collected from crannies and hollows in trees in dense rain forest. 
Natives state the species is completely arboreal. Two other spe- 
cies of Cyrtodactylus, papuensis and mimikanus, are sympatric 
with derongo, and were observed both on the forest floor and on 
trees a few feet above the ground. A possible fourth species, also 
arboreal, was observed in the same area but specimens are not 
availal)le for identification. 

Comparisons. Differs from other Indo-Australian species of 
Cyrtodactylus in the rather uniformly dark ground color of dor- 
sum marked by large white tubercles. The color pattern is remi- 
niscent of that of Underwoodisaurus milU, but in the latter the 
white patches in\'olve small surrounding scales, and the patches 
may be fused into partial or complete transverse bands. Com- 
pared to other New Guinean species, C. derongo is somewhat 



1973 CYRTODACTYLUS DERONGO 5 

intermediate in size along with mimikanus, marmoratus, papuen- 
sis, and pelagicus, and in contrast to the diminutive vankampeni 
and the larger loriae, louisiadensis and novaeguineae. It also 
differs from other species, with the possible exception of novae- 
guineae (not examined), in the pattern of enlarged preanal 
and femoral scales, and in lacking enlarged scales posterior to 
the pore series in the preanal area. C. pelagicus and vankampeni 
exhibit no or only ver\^ slightly enlarged scales in the pore series; 
loriae, louisiadensis, mimikanus, marmoratus, and papuensis ex- 
hibit 3 to 8 or 9 short rows of large scales posterior to the pore 
series in the preanal area. 

Key to Cyrtodactylus From New Guinea 

1. a. Preanal region, or both preanal and femoral regions, with one or more 

rows of distinctly enlarged scales 3 

b, Preanal and femoral regions covered by relatively uniform small scales, 
even the pore series not distinctly enlarged 2 

2. a. Dorsal rows of tubercles at mid-body 22-24, usually 10 at region of fore 

limbs; 8-12 preanal pores, femoral pores absent pelagicus 

b. Dorsal rows of tubercles at mid-body 10-12, usually 6 at region of 
fore limbs; 45-50 preanal and femoral pores in a continuous series. 

vankampeni 

3. a. Dorsum usually marked by a pattern of light and dark bands or 

distinct dark , blotches of varying size; or if melanistic, lacking promi- 
nent, white tubercles 4 

b. Dorsum dark brown with very faint darker blotches enclosing promi- 
nent, white tubercles, which tend to form narrow, irregular, partial or 
complete transverse series; a continuous series of preanal and femoral 
pore scales (females) preceded anteriorly by several rows of enlarged 
scales, those in the preanal region merging with those of the venter; 
no enlarged scales posterior to the pore series in the preanal region 
derongo 

4. a. One or more rows of enlarged femoral scales; upper labials usually not 

greater than 12 ^ 

b. No enlarged femoral scales; 12-14 upper labials; 10 11 broad lamellae 

' under basal portion of fourth toe; dorsum with a double or united 

series of 5 or 6 rather large dark blotches between ear region and base 

of tail, separated by light bands variably marked by 3 or 4 smaller 

dark blotches; males without pores sermoivaiensis 

5. a. Enlarged preanal pore scales in a shallow "/\" chevron 7 

b. Enlarged preanal pore scales compressed into a narrow "/\" sunk in a 

groove in males with 8-14 pores 6 

6. a. Seven to 9 moderately narrow, dark, irregularly margined bands or 

series of blotches between the ear region and the groin; 8-10 preanal 



6 BREVIORA No. 417 

pore scales bearing pores in males, preceded anteriorly by 1 or 2 rows 
of much enlarged scales and followed posteriorly by a narrow cluster 
of 8-12 enlarged preanal scales; preanal series widely separated from 
a single row of much enlarged femoral scales; no femoral pores. 

papuensis 

b. Seven to 9 irregularly margined, dark bands or blotches between the 
ear region and the groin; 12-14 preanal pore scales bearing pores in 
males, preceded anteriorly by several rows of enlarged scales merging 
with those of the venter and followed posteriorly by several rows of 
enlarged scales which diminish gradually; several rows of enlarged 
femoral scales continuous with the enlarged preanal series; a short 

series of 4-6 femoral pores separated from the preanal series 

marmoratus 

7. a. Dorsum with five broad, dark, rather even-margined, transverse bands 

or double series of blotches between the ear region and the groin; 
26-28 irregular rows of rather small, unikeeled tubercles between lateral 
folds at mid-body; a continuous series of enlarged preanal and femoral 
pore scales bearing 38-80 pores^ for several males examined but in each 
instance reaching the distal end of the femur, both preceded anteriorly 
by several rows of enlarged scales merging with those of the venter in 
the preanal region, followed posteriorly by several rows of enlarged 

preanal scales that diminish gradually loiiisiadensis 

b. Dorsum with 5 to 8 broad to narrow dark bands or series of blotches, 
usually with irregidar margins, between the ear region and the groin; 
20-22 irregular rows of tubercles between lateral folds at mid-body; a 
continuous or interrupted series of preanal and femoral pore scales, 
some bearing pores in males 8 

8. a. Dorsmn with 5 dark transverse bands or series of blotches between the 

ear region and the groin; males with a continuous series of preanal and 

femoral pores 9 

b. Dorsum with 7 or 8 dark transverse bands or series of blotches between 
the ear region and the groin; a series of enlarged preanal scales bear- 
ing 12-14 pores in males; often separated by 3 or 4 somewhat smaller 
scales from the pore-bearing femoral series; in males the latter bearing 
a median group of 0-5 pores and a distal group about 5-11 pores on 
either side; both preanal and femoral series preceded anteriorly by 
several rows of enlarged scales which in the body region merge ^vith 
those of the venter; and in the preanal region also follo^\•ed posteriorly 
by several rows of enlarged scales which gradually diminish in size. 
mimikanus 

9. a. A continuous series of preanal and femoral pores extending the length 

of the femur, bearing in males an uninterrupted series of 60-70 pre- 



^This wide range may reflect population differences, since in our small 
sample those with the lowest number of pores were from Australia and those 
with the largest number from the Solomon Islands. 



1973 CYRTODACTYLUS DERONGO 7 

anal and femoral pores; preanal pore series preceded by several rows 
of enlarged scales merging with those of the venter, and followed 
posteriorly by 3 or 4 rows of enlarged scales; femoral scales anterior to 
the pore series exhibiting a gradual reduction in number of scales and 
a resultant strongly tapered appearance; 20-24 lamellae and enlarged 
scales beneath the fourth toe; small, roundish tubercles absent from 

throat loriae 

b. A series of enlarged preanal and femoral pore scales, bearing a con- 
tinuous series of 38-42 preanal and femoral pores in males; 28-33 
lamellae and enlarged scales under the fourth toe; throat with some 
scattered small rounded tubercles (from description by Brongersma, 
1934) novaeguineae 

Literature Cited 

Brongersma, L. D. 1934. Contributions to Indo-Australian Herpetology. 

Zool. Meded., 17: 161-251, 2 pis. 
DE Rooij, N. 1915. The Reptiles of the Indo-Australian Archipelago. I. 

Lacertilia, Chelonia, Emydosauria. Leiden, xiv + 384 pp. 
Inger, R. F. 1958. A new gecko of the genus Cyrtodactylus with a key to 

the species from Borneo and the Philippine Islands. Sarawak, Mus. 

Journ., 8: 261-264. 



J 



~t\J(\ r\( \ > 




B R-feaT^ I R A 

Museum JAS^toOTparative Zoology 

HA RVfcTissN o()or>-9r>98 



Cambridge, Mass. 28 December 1973 Number 418 

MORPHOGENESIS, VASCULARIZATION AND 
PHYLOGENY IN ANGIOSPERMS^- -" 

G. Ledyard Stebbins^ 

Abstract. Evidence is reviewed to support the hypothesis that vascular 
strands in the angiosperm flower which some botanists have regarded as 
"vestigial" can be understood better if they are regarded as the result of 
irregularities in development, which provides no indication with respect to 
the alternatives of phylogenetic reduction vs. amplification. Nevertheless, 
the concept of the conservatism of vascidar anatomy is supported by the 
proljability that genes acting late in development can more easily give rise 
to mutations that can become incorporated into a harmonious genotype 
than can genes that act early in development. Examples from the develop- 
ment of achenes in various genera of the family Compositae show that size 
of mature achene is not necessarily correlated with complexity of vascular 
anatomy, and that this anatomy may reflect the particular course of develop- 
ment, particularly the time when procambial initials are differentiated. In 
this family, genera that are generally regarded as more closely related to 
each other tend to have more similar developmental patterns than those 
that are more distantly related. 

Ever since the 19th-century research of Celakovsky (1896), 
botanists have asked the question: "Is the arrangement of vascu- 
lar bundles in the organs of higher plants a more reliable guide 
thar) outward form to homology and the direction of evolution?" 
Until verv recently, the usual answer has been affirmati\'e 
(Eames, 1931, 1961; Puri, 1951, 1952; Melville, 1962), al- 

^Much of the material in this paper is reproduced from the author's book: 
Flowering Plant Evolution Above the Species Level, Harvard University 
Press (in preparation) , through kind permission of the Press. 

-This paper is respectfully dedicated to my former teacher and mentor, 
Ralph H. Wetmore, who was largely responsible for developing my interest 
in comparative plant anatomy. 

•Department of Genetics, University of California, Davis 



2 BREvioRA No. 418 

though botanists have differed widely with respect to interpre- 
tations of anatomical structure. In particular, single vascular 
bundles that appear to have no function have been designated 
as "vestigial." They have been interpreted as vestiges of organs 
that are no longer formed, and therefore as indicating wide- 
spread, predominant trends of reduction. Furthermore, the 
concept of "fusion" has been adopted to interpret situations in 
which two related species or genera differ with respect to the 
number of parallel bundles found in an organ. If a form has 
two parallel bundles in a particular position, it is regarded as 
more generalized or primitive than a related form that has only 
one bundle in that position. 

During the last decade, botanists have become increasingly 
skeptical of such notions. An extreme form of this skepticism 
has been expressed by Carlquist (1969). x\fter an extensive 
review of the entire problem, he reaches the following conclusion 
(p. 334) : "Anatomy of flowers can be studied meaningfully 
only in relation to adaptations for particular modes of pollina- 
tion, dispersal and allied functions." 

In my opinion, neither the rigid interpretations of Eames, 
Puri, Melville and their followers nor the complete skepticism of 
Carlquist are justified. Later in this article, examples are given 
to show that when comparing even such similar and certainly 
homologous structures as the achenes of different Compositae, 
one finds many exceptions to a supposed correlation between 
organ size and complexity of \'ascularization. On the other hand, 
se\'eral examples exist in the literature to show that supposed 
"vestigial ]:)undles" can be associated with either increase or 
decrease in numbers of parts. One of the clearest of these was 
presented long ago by Murbeck (1914). In two species belong- 
ing to the family Rosaceae, Comarum palustre and Alchemilla 
vulgaris (sens. lat. ), he found rare de\iations from the normal 
or modal number of calyx lobes, in both an upward and a down- 
ward direction. In Alchemilla, for instance (Fig. 1), the normal 
number of lobes is four, but occasional flowers have three lobes 
and others have five. Most important, however, is the fact that 
among 3-lobed as well as among 4-lobed calyces are examples 
in which one of the lobes is larger, and may have a double- 
pointed apex, as well as extra vascular bundles. According to 
the classical interpretation, such 3-lobed calyces result from 
a trend of reduction via "fusion," and the extra bundles found 
in the larger lobe are "vestigial." If, however, this interpretation 



1973 



ANGIOSPERMS 














Figure 1. Calyces of individuals of Alchemilla vulgaris, showing devia- 
tions from the normal 4-merous condition in the direction of both decrease 
and increase in lobe number, as well as intermediate situations with ab- 
normal lobe number and structure. From Murbeck, 1914. 



4 BREVIORA No. 418 

is to be consistent, the larger lobes of the aberrant 4-lobed calyces 
would have to be interpreted in the same way, and the conclu- 
sion would have to be reached that the basic number of calyx 
lobes in Alchemilla vulgaris is five rather than four. Such an 
interpretation is contradicted by the fact that 4-merous calyces 
are found throughout the genus Alchemilla, except for rare aber- 
rant indi\iduals like those described by Murbeck. In Comarum 
palustre, similar aberrant calyces have five lobes, one of which 
is larger than the others and contains extra vascular bundles. If 
one held strictly to the concept of reduction and vestigial bun- 
dles, one would have to interpret these calyces as indicating that 
the calvx of Comarum was oris^inallv hexamerous. Since hex- 
amerous calyces are almost completely lacking, not only in the 
family Rosaceae but also in the entire order Rosales, such an 
interpretation is absurd. 

A MORPHOGENETIC InTREPRETATION OF 

"Vestigial Bundles" 

These examples are best interpreted by discarding entirely the 
concept of reduction and vestigial bundles, as well as any other 
phylogenetic concept, and regarding them entirely in the light of 
developmental genetics. The aberrant calyces found by Murbeck 
are comparable to the aberrant corollas described by Huether 
(1968) in Linanthus androsaceus, and shown by him to repre- 
sent unusual gene combinations that render the plant more sus- 
ceptible than normal individuals to producing aberrant pheno- 
types, or phenodeviants, as a result of normal environmental 
fluctuations during development. Deviations from the normal 
or modal condition can occur in either direction. Using a de- 
velopmental approach, they can be explained on the basis of a 
formula that I suggested a few years ago (Stebbins, 1967). The 
number of similar organs or parts that are produced in a 

particular whorl can be represented by the quotient A" + ^. , 

a 

where A" is the final number of parts, a'" is the total number of 
meristematic cells that are capable of producing an A-type part, 
and a' is the number of meristematic cell initials needed to pro- 
duce a single A-type part. 

Applying this formula to Murbeck's examples, one could sug- 
gest that in the normal development of the calyx of Alchemilla, 
the relation of a"^ to a' is on the order of 20 to 5, so that A" = 4. 



1973 ANGIOSPERMS 5 

In the extreme aberrants, a' remains the same, but a" has become 
respectively 15 and 25. On the other hand, 3-lobed calyces of 
which one lobe is lar2:er and has extra bundles would result from 
values such as a"^ = 17 and a^ = 5, so that A" = 3.4. Similarly, 
abnormal 4-lobed calyces would represent the quotient A" = 4.4, 
resultins: from values of A"^ = 22 and a' = 5. 

Morphogenetic evidence with respect to "vestigial" bundles 
in the androecium of various species belonging to the order 
Malvales has been obtained by van Heel (1966). He showed 
that in several instances vascular bundles, which in the mature 
flower were not associated with any recognizable structure, 
ne\'ertheless appeared in a position where small stamen primordia 
could be recognized in early stages of development. These 
primordia later became enveloped by the growth of the sur- 
rounding tissue, presumably produced by persistent intercalary 
meristems. These examples could be regarded either as terminal 
stages of a reduction series, or intermediate stages of a trend 
toward amplification. 

The most convincing evidence regarding the morphogenetic 
significance of vascularization comes, however, from experiments 
in which the conditions under which vascular tissue appears 
have been determined, or have been altered in specific ways. 
Only two such experiments are known to me. One of them, by 
\\'etmore and Rier (1963), showed that vascular tissue arises 
in callus tissue at positions that are at regular distances from 
each other, and that their distributional pattern can be altered 
as a result of relatively slight alterations in the nutritive medium. 
Consequently, the appearance of a bundle in an unexpected 
position requires only a slight shift in the distribution of nutri- 
tional factors or in the balance of hormonal interactions within 
the developing system. 

In the other experiment, Torrey (1955, 1957) altered ex- 
perimentally the number of protoxylem points in a pea root. 
He^ found that when 0.5 mm of the distal portion of the root, 
containino- onlv cells that are not visiblv differentiated, was iso- 
lated and cultured in vitro, the great majority of cultures pro- 
duced roots having the normal triarch condition. About 2 percent 
of the cultures, however, which were tips of relatively small size, 
produced at first diarch roots, which later reverted to the triarch 
condition. 

If to the culture he added indole acetic acid at a concentration 
of lO""" molar, he obtained a greater proliferation of the cells 



6 BREVIORA No. 418 

from which vascular tissues are differentiated. As a result, he 
converted the triarch to the hexarch condition, and found that 
the latter condition persisted indefinitely. The number of pro- 
toxylem points could, therefore, be increased or decreased, de- 
pending upon the amount of meristem present when procambial 
differentiation took place. 

These two experiments suggest that much can be learned 
about the processes that affect the pattern of vascularization 
by various kinds of experimental approach. This is a field of 
morphogenesis that has not yet been well developed but that 
promises eventually to provide a bridge over which visible 
changes in vascular anatomy can be related to specific alterations 
of the genot\pe, as they affect developmental processes. 

Vestigial Characters in Plants and Animals 

The results just reviewed suggest that with respect to any 
group of similar structures, such as parts of a perianth, stamens 
in an androecium, or "carpels" in a gynoecium, evolutionary 
change can involve either increase or decrease in number, and 
that the anatomical features associated with either trend are 
similar to each other. Vascular anatomy cannot tell us whether 
or not the ancestors of a particular form had more or fewer 
sepals, petals, stamens, or carpels. 

The belief of plant anatomists that this is possible rests, in my 
opinion, on a mistaken analogy with the genuine vestigial struc- 
tures found in animals. These latter, such as the gill slits of the 
x'ertebrate embryo and the vermiform appendix, have a complex 
and distinctixe developmental pattern. The so-called "vestigial 
bundles," on the other hand, are identical in structure with the 
bundles that are unquestionably functional. Furthermore, the 
procambial cells that form the xylem and phloem of these bun- 
dles are probably differentiated from meristematic cells during a 
single mitotic cycle (Olson et ai, 1969). More important, the 
epigenetic sequence responsible for the formation of these bun- 
dles is an exact repetition of a course of events that occurs in 
many other parts of the plant; only the position w^here it occurs 
is distincti\e. 

A Developmental Hypothesis That Favors 
Conservatism of Vascular Anatomy 

The concept of vestigial bundles is part of a broader concept 



1973 ANGIOSPERMS 7 

that \'iews \'asciilar anatomy as more conservative than external 
morphology. This concept has been rejected by Carlquist ( 1969) 
as an "insufficient and fallacious framework on which most 
phylogenetic interpretations of floral anatomy still rest." He 
ne\'ertheless concedes that degree of union between vascular 
bundles can be "conservative." Is there any logic to this ac- 
ceptance of a part of the doctrine of conservatism, after most 
of it has been rejected? 

I belie\e that botanists must examine the problem from the 
viewpoint of developmental genetics and morphogenesis, since 
this brings us closer to the basic nature of evolutionary changes. 
When we do this, we can recognize and emphasize the fact that 
the procambial initials from which vascular bundles arise become 
differentiated from the ground meristem at a very early stage 
of the de\'elopment of primordia. Consequently, alterations of 
vascular pattern require changes in the time of action of genes 
that normally act very early in development. Alterations in the 
action of genes that normally act at later developmental stages 
can produce changes in size or form without altering the pattern 
of vascularization. 

Is there any logical reason for assuming that genes which 
produce their effects at early stages of development are less likely 
to play a role in evolutionary change than genes which affect 
later stages? A positive answer to this question is the genetic 
basis for recognizing Von Baer's principle of embryonic similar- 
ity, which was used by Darwin (1872) as embryological evi- 
dence for evolution, and has been applied more recently to 
animal development by De Beer ( 1 95 1 ) , and to plants by the 
present author (Stebbins, 1950). The reasoning is as follows. 
Adult characteristics are assumed to be the products of epi- 
genetic sequences of gene action in development, so that later 
processes depend in part upon the nature of gene products pro- 
duced at earlier developmental stages. Moreover, the action of 
most genes is pleiotropic in the sense that their primary products 
may have many secondary effects. The earlier is this primary 
action, the greater is the amount of pleiotropy that is possible, 
and the more widespread are the secondary effects of genes. 
Hence mutations of genes affecting early stages are more likely 
to produce profound alterations of development, and hence to 
upset the entire developmental system, than are mutations of 
late-acting genes. The milder alterations produced by these 
latter mutations are more likely to adjust the individual in a 



8 BREVioRA No. 418 

harmonious fashion to new selecti\'e pressures than are the more 
drastic effects produced by mutations of genes that act early in 
de\'elopment. Hence, adaptive alterations of morphology are 
brought about more often by ]ate-acting genes than by those 
acting early in de\'elopment. In other words, genes acting early 
in de\elopment tend to be conser\'ative with respect to the estab- 
lishment of their mutations in populations. Among such genes 
are those that affect the differentiation of procambial strands. 



Relationships Between Organ Size and 
Amount of Vascularization 

In the remainder of this contribution, I would like to apply 
the theoretical concept just developed to two situations. The first 
is the relationship between organ size and amount of vasculariza- 
tion. If vascularization is related only to adaptation and physio- 
logical function, as Carlquist has assumed, then large organs 
should always have a proportionately greater amount of vascu- 
larization than homologous, smaller ones. On the other hand, if 
preferential establishment of late-acting gene changes is a sig- 
nificant factor, then the relationship between size and vascular- 
ization w^ould ha\'e a historical or evolutionary component. 

Among homologous organs having approximately the same 
size, but different patterns of vascularization, one might postulate 
that the one having the more complex pattern resembles most 
closely the most primitive organ of the group in question, while 
the simpler pattern has been derived by a process of reduction 
that affected early stages of development, followed by a reversal 
of evolutionary direction, in which increase in size was accom- 
plished by establishment of genes acting late in development. 
Similarly, in comparisons between homologous organs of very 
different sizes, but having similar, relatixely simple patterns of 
vascularization, one might postulate that the smaller organ more 
nearly resembles a reduced, ancestral form, and the larger one 
has been deri\'ed via secondary enlargement. 

Ovary and Achene Development in the 
Family Com po sitae 

A good object for testing these hypotheses is the ovary and 
achene in the family Compositae. In different genera of this 



1973 



ANGIOSPERMS 



9 



f f 



A 








12-28 VASCULAR STRANDS 



D 



I I 



£ 



\ » 



(I 



10 VASCULAR STRAKDS 



// n 




5 V^CULAR STRAKDS 



Figure 2. Mature achenes of various species of Compositae of which the 
development is recorded in Tables 1 and 2. A, Helianthus annuus, wild 
form from east of Davis, Calif. B, Helianthus annuus, cultivated variety 
from Department of Agronomy, University of California, Davis. C, Wyethia 
glabra, from Cache Creek Canyon, Yolo County, Calif. D, Senecio cruentus, 
cult. var. "stellata" (smaller heads) . E, Senecio vulgaris, from campus. Uni- 
versity of California, Davis. F, Microseris nutans, from Wright's Lake, 
Eldorado County, Calif. G, Tragopogon porrifolius, from Locke, Sacramento 
County, Calif. H, Stephanomeria exigua ssp. coronaria, from Antioch, 
Calif. I, Microseris douglasii, from south of Dixon, Solano County, Calif. 



10 BREVIORA No. 418 

family, an enormous range of size exists between mature achenes 
having a length of 1.4 mm to achenes 20 times as long, and 
many-fold greater in bulk (Fig. 2). With respect to anatomy, 
the most complex patterns consist of 26 to 28 parallel bundles 
traversing the ovar\^ and achene (Stebbins, 1940), while in the 
simplest ones, only two bundles are present (Stebbins, 1937). 
The poor correlation between size and complexity of vascu- 
larization is shown in Figure 2, which illustrates the mature 
achenes of ten forms belonging to this family. In three of these 
(A-C), the ovary and achene are traversed by 12 to 28 parallel 
vascular strands, while in the remaining three (G-J) only five 
are present. In the first group, achene length ranges from 
2.92 mm to 13.65 mm; in the second, from 1.4 mm to 5 mm; 
and in the third, from 3.8 mm to 28.5 mm. I admit that the 
largest example of the latter group, Tragopogon porrifolius, was 
chosen to represent an extreme example of large size associated 
with a relatively simple vascular pattern, so that one cannot 
conclude from this tiny sample that an inverse correlation exists 
between achene size and amount of vascularization. Neverthe- 
less, the lack of a significant positive correlation in the family as 
a whole seems to me highly probable on the basis of my acquaint- 
ance with a large number of genera. 

In order to discover more about the relationships between 
vascularization and developmental patterns, I have compared 
the ovaries of these species at four stages of development: 
( 1 ) the smallest size at which procambial strands can be recog- 
nized ; ( 2 ) the first appearance of xylem tracheids ; ( 3 ) anthesis ; 
and (4) mature achenes. Since the Composite achene increases 
far more in length than in width, mean length of the ovary at 
each of these stages is a reliable indicator of overall size. The 
stages were determined both from sectioned material and from 
whole mounts cleared according to the schedule of Herr (1971) 
and observed under Nomarski interference-contrast optics. 

Preliminary results of this study are shown in Tables 1 and 2. 
Table 1 gi\'es the mean lengths of the ovary and achene at four 
different stages: differentiation of procambium; first differen- 
tiation of xvlem strands, anthesis, and seed maturity. The 
final column of this table gives the mean number of vascular 
strands in the ovary at anthesis. Table 2 presents the mean 
percentage growth increment for each interval between the 
stages listed in Table 1. To obtain these values, the difference 
between the length at a later stage and at the next earlier stage, 



1973 



ANGIOSPERMS 



11 



Table 1. Lengths of ovaries and achenes of some species and varieties of 
Conipositae at selected stages. 



Procambial Xylem 
differen- differen- 
tiation tiation 



(P) 



(X) 



Xylem 
strands 
An thesis Maturity at 

(A) (M) an thesis 



0.253mm 0.631mm 11.25mm 13.65mm 12-17 



Species or variety 
Wyethia glabra 
Helianthiis bolanderi 
ssp. exilis 

Helianthus annuus 
wild (neai" Davis, Cal.) 
Helianthus annuus 
cultivated 
Senecio cruentus 
cult, small heads 
Senecio cruentus 
cult, large heads 
Senecio vulgaris 
Microseris nutans 
Microseris douglasii 
Stephanomeria exigua 
Tragopogon porrifolius 



Table 2. Proportional growth increments at successive stages of ovaries of 
Conipositae. Symbols explained in Table 1, and in text. 



0.198 


0.291 


2.01 


2.92 


19-21 


0.251 


0.38 


1.596 


5.52 


18-24 


0.208 


0.442 


9.90 


13.65 


26-28 


0.234 


0.732 


0.868 


1.43 


10 


0.228 


0.61 


1.41 


1.66 


10 


0.186 


0.772 


1.135 


2.35 


10 


0.294 


0.997 


1.366 


5.04 


10 


0.194 


0.999 


1.67 


4.96 


5 


0.205 


0.524 


1.449 


3.86 


5 


0.242 


0.934 


1.912 


28.5 


5 





X-P 


AX 


MA 




P 


X 


A 


Species or variety 








Wyethia glabra 


1.49 


16.8 


0.23 


Helianthus bolanderi 








ssp. exilis 


0.47 


5.91 


0.45 


Helianthus annuus 








wild 


0.51 


3.20 


2.46 


Helianthus annuus 








cultivated 


1.12 


21.40 


0.38 


Senecio cruentus 








cult, small heads 


2.12 


0.17 


0.65 


Senecio cruentus 








cult, large heads 


1.70 


1.31 


0.18 


Senecio vulgaris 


3.10 


0.47 


1.07 


Microseris nutans 


2.39 


0.37 


2.69 


Microseris douglassi 


4.15 


0.67 


1.97 


Stephanomeria exigua 


1.56 


1.77 


1.66 


Tragopogon porrifolius 


2.85 


1.05 


13.91 



12 



BREVIORA 



No. 418 



WyetKia 
glabra 



Helian-thus 
bolanderi 



Helianthui 
annuus wild 



Small l^eacis Large heads 

Senecto cruen+us 



Senecio 
vulgaris 



HeliantKus 
annuus cult. 



Microseris 
nutans 



fiicroseris 
douglasM 



StepKanomeria 
exigua 



Traqopogon 
porrifolius 



Figure 3. Chart showing diagramatically the growth increments of ovaries 
of Compositae, as recorded in Table 2. 



1973 ANGIOSPERMS 13 

i.e., the amount of growth during the interval, is divided by the 
length at the earlier stage. In this way, growth during each 
inter\'al between stages is expressed in proportion to the amount 
of tissue or "meristematic capital" present at the beginning of 
the interval under study. In Figure 3, the same results are pre- 
sented graphically. 

These figures show that the amount of growth which takes 
place before the vascular pattern is laid down by procambial 
differentiation is only a small percentage of the total growth of 
the organ. Moreover, this percentage varies greatly from one 
species to another. The size of the primordium at the time of 
procambial differentiation is similar in all of the species studied, 
ranging from 186 micra in Senecio vulgaris to 294 micra in 
Microseris nutans. This range is far less than the extreme differ- 
ences in size between mature achenes, so that the percentage of 
growth in length that takes place before procambial differentia- 
tion ranges from high figures to 14 to 16 percent in Senecio 
cruentus to the extremely low figure of 0.9 percent in Tragopo- 
gon porrifolius. 

Two obvious conclusions can be made from these results. 
First, developmental patterns differ widely from one species to 
another of this family, and may even differ between varieties of 
the same species, as in Helianthus annuus and Senecio cruentus. 
Second, each of the tribes represented possesses a characteristic 
series of patterns that are different from those found in other 
tribes. In the Heliantheae, for instance, the greatest percentage 
increase in size occurs between procambial differentiation and 
xylem differentiation. The Cichorieae are more variable in this 
respect, but show a greater tendency than other tribes toward 
growth between anthesis and achene maturity. 

A further conclusion can be drawn by comparisons between 
members of the same tribe. In both of the comparisons between 
cultivated varieties of the same species: wild vs. cultivated 
Helianthus annuus and the two cultivated varieties of Senecio 
cruentus, the greatest difference exists with respect to size in- 
crease between xylem differentiation and anthesis, a stage during 
which few or no mitotic divisions are taking place. In Senecio, 
this is also the stage at which the greatest difference exists be- 
tween the two species studied: S. vulgaris and S. cruentus. In 
the Heliantheae, the two wild species of Helianthus differ most 
from Wyethia glabra with respect to the increase at this stage, 



14 BREVIORA No. 418 

but the greatest difference between H. annuus and H. Bolanderi 
is with respect to the stage between anthesis and seed maturity. 
In the Cichorieae, the most divergent species, Tragopogon por- 
rifolius, differs most from the others with respect to this last stage. 

These results support, in general, the hypothesis that later 
developmental stages are more easily modified at the level of 
varieties and species than are early stages. In all of the varietal 
and species comparisons, except for the species of Microseris, 
stages after xylem differentiation differ more than do earlier 
stages. Furthermore, the size of the primordium at the time of 
procambial differentiation is strikingly similar among all of the 
forms studied, at least in comparison to the much greater differ- 
ences between their mature achenes. Finally, with respect to the 
two examples of artificial selection for increased size, genetic 
changes affecting later stages were established in preference to 
those affecting earlier stages. 

The comparison between the two species of Microseris pro- 
vides a significant exception to the above generalization. The 
annual species, M. Douglasii, differs from the perennial M. 
nutans with respect to the smaller size of the o\'ary primordium 
at the stage of procambial differentiation, and the proportion- 
ally greater amount of growth that takes place between this stage 
and that of xylem differentiation. This suggests that Af. Doug- 
lasii arose from its perennial ancestor, which certainly was not 
M. nutans, but may have been a species having a similar devel- 
opmental pattern, via reduction in the size of the ovary primor- 
dium, accompanied or followed by compensatory growth at later 
stages. This reduction, which affected an early developmental 
stage, may have been responsible for the reduction from ten 
ovarian bundles, which is characteristic of M. nutans and other 
perennial species of Microseris, to five bundles, as found in most 
or all of the annual species, including M. Douglasii. 

This small and admittedly inadequate sample supports, as far 
as it goes, the hypothesis that large achenes having simple 
vascular patterns are deri\ed by secondary enlargement from 
smaller ones having similar vascularization. VV^ith respect to the 
hypothesis that simplification of vascular pattern takes place via 
a "bottleneck" of reduction that affects early developmental 
stages, followed by secondary enlargement, the present evidence 
is inconclusive. I hope, however, to obtain an answer to this 
question when the study is complete. 



1973 ANGIOSPERMS 15 

A Basis For Differentiating Between Primary 
AND Secondary Union of Parts 

The second kind of situation that I would like to discuss con- 
cerns the validity of vascular patterns as evidence for the phylo- 
genetic origin of "fusions" and "adnations" between parts. This 
topic has been much discussed in connection with the origin of 
the inferior ovaiy, or epigyny (Douglas, 1957; Kaplan, 1967). 
The extreme skepticism of Carlquist ( 1969) with respect to such 
evidence has been challenged by Kaplan (1971), who in my 
opinion has successfully answered many of Carlquist's criticisms. 
At any rate, since diverse vascular patterns are found in various 
genera having epigynous gynoecia, is association with other very 
dififerent morphological characteristics as well as affinities to 
various groups having perigynous or hypogynous gynoecia, this 
evidence indicates strongly that the epigynous condition has been 
evohed many times independently in different orders of plants, 
by various evolutionary pathways. 

In my discussion, however, I should like to focus attention on 
the androecium. The "fusion" of stamens into bundles or a 
tubular staminal column that includes the entire androecium is a 
familiar feature in several plant families, particularly the Mal- 
vaceae, Sterculiaceae, Hypericaceae (Guttiferae), Myrtaceae, 
and some genera of Dilleniaceae. This "fusion" is generally 
regarded as secondary (Eames, 1961), and in most instances 
this conclusion is well justified. Developmentally, it is most often 
brought about by a suppression of differentiation with respect to 
stamen filaments. Instead of separate intercalary meristems that 
produce the growth of each individual filament, a common 
meristem elevates some or all of the anther primordia on a single 
column, tube or sheath (van Heel, 1966). 

Recent developmental studies, however, suggest that not all 
"fusions" between stamens are of this secondary kind. In Pae- 
oni'a (Hiepko, 1965) and Hypericum (Leins, 1964; Robson, 
1972) careful analyses of the development of floral primordia 
have shown that stamen bundles, not individual anther pri- 
mordia, fit into the phyllotactic sequence that is followed by the 
other floral parts. Furthermore, anther primordia arise not from 
the undifferentiated meristem of the reproductive axis, but from 
distinct primordia of stamen bundles. Their differentiation pre- 
cedes the activity of the intercalary filament meristem, which in 



16 BREVIORA No. 418 

Paeonia and Hypericum ele\'ates each stamen upon a separate 
filament. 

The anatomical condition that follows this developmental 
pattern is that of a common "trunk" vascular strand for each 
cluster of stamens that are differentiated from the same bundle 
primordium. The vascular strands that supply indi\idual sta- 
mens di\erge from the "trunk" strand, not directly from the 
floral axis. 

Examination of the \'ascular anatomy of the mature androe- 
cium in a number of relatively primiti\'e angiosperms, such as 
Degeneria (Swamy, 1949), Hibbertia (Wilson, 1965), and 
certain Annonaceae {Cananga, Goniothahnus, unpublished ob- 
servations of the present author), has revealed the same kind of 
bundle pattern in them. In most instances, this pattern is not 
accompanied by an ob\ious clustering of the stamens in the 
flower as view^ed externally. This condition leads me to believe 
that, although in some instances such stamen bundles may have 
been deri\'ed from single stamens by a process of multiplication 
of another primordia, or "dedoublement," as Leins (1964, 1971 ) 
maintains, this has not always been so. Conclusions based upon 
comparisons between o\ules and megasporophylls, which will be 
presented elsewhere, have led me to believe that among known 
fossil forms, those most nearly related to ancestors of the angio- 
sperms are the cupule-bearing Pteridosperms such as Caytoniales 
(Thomas, 1925) and Corystospermaceae (Thomas, 1933). If 
this hypothesis is correct, then the structure of the microspro- 
phylls in these forms should be considered. In no case do they 
consist of flat structures bearing sporangia upon their surfaces, 
as would be expected on the basis of the "classical" concept of 
the origin of stamens (Eames, 1961 ). They are always branched, 
and bear numerous microsporanma at the ends of the branches. 
The stamen bundles in genera like Paeonia could be derived 
from such microsporangiophylls by suppression of their branches. 
This discussion can be summarized by stating the hypothesis 
that "fusions" of stamens are of two kinds. The existence of 
stamen bundles that are evident chiefly from examination of the 
vascular pattern, and are seen with difficulty or not at all when 
one examines the external structure of the flower, represents a 
primary fusion, which takes place at the very earliest stage of 
androecial de\elopment, and reflects an ancestral condition. On 
the other hand, the staminal tube of the Malvaceae, and the 
elevated clusters of stamens that are found in many genera of 



1973 ANGIOSPERMS 17 

Hypericaceae and Myrtaceae, as well as similar structures in 
\'arious other families, are secondary in origin, and are produced 
by intercalary meristems that appear relatively late in develop- 
ment, after the anther primordia are fully differentiated. This 
hypothesis is entirely in accord with that of conservatism of gene 
complexes affecting early de\'elopmental stages. 

A Plea For Further Research in the Field 

OF MORPHOGENETIC TaXONOMY 

The account which I have just given of the comparative de- 
\'elopment of achenes in the Compositae reports only the begin- 
ning of a small piece of research. Nevertheless, it shows that 
careful comparisons between developmental patterns of selected 
organs in a series of closely related forms can reveal similarities 
and differences that are not evident from examinations of mature 
organs. Moreover, some of these differences in pattern can serve 
as a guide to evolutionary direction. 

In their efforts to broaden their field, botanists have, in recent 
years, been relying to an increasing extent on characteristics 
other than external morphology. Cytotaxonomy, based upon 
chromosomal differences, has been with us for a long time. More 
recently, chemotaxonomy has increased in popularity, and is 
yielding highly significant results. In my opinion, the essentially 
undeveloped field of morphogenetic taxonomy also needs to be 
developed. Its potential importance lies in the prospect that it 
may contribute more to our understanding of morphological 
taxonomy than any other field. The cytotaxonomist studies 
chromosomes as they appear during mitosis, when the DNA is 
condensed into neat packages, and the genes are inactive. In- 
numerable studies in this field have shown us that the number 
and shape of these "packages" is much less important for adap- 
tation, survival, and ecological distribution than is the nature of 
the genes contained in them. Chemotaxonomists, because of the 
cornplexity of their field, have been forced to concentrate upon 
certain compounds and properties largely because of technical 
considerations that determine the ease of study rather than cri- 
teria of evolutionary significance. We have, therefore, many 
systematic comparisons of secondary and accessory compounds 
such as phenolics and terpenes, as well as of a single property, 
electrophoretic mobility, possessed by those proteins that are 
easily isolated and recognized. Important as these investigations 



18 BREvioRA No. 418 

are, they explore only the fringes of the biochemical systems of 
the organisms concerned. 

The potential value of morphogenetic taxonomy arises from 
the fact that adult structures appear as a result of patterned 
sequences of gene action in development. Groups of genes are 
acti\'ated and deactivated according to a specific program that 
is controlled by a complex system of regulator genes (Britten 
and Davidson, 1969). Morphological evolution must be based 
ultimately upon mutations and recombinations of these par- 
ticular genes. By developing the discipline of morphogenetic 
taxonomy, botanists may be able to approach closer to an under- 
standing of how these genes work, and how they change during 
evolution. 

Literature Cited 

Britten, R. J., and E. H. Davidson. 1969. Gene regulation for higher cells: 

a theory. Science, 165: 349-357. 
Carlquist, S. 1969. Toward acceptable evolutionary interpretations of 

floral anatomy. Phytomorpholog)', 19: 332-362. 
Celakowsky, L. 1896. tjber den phylogenetischen Entwicklungsgang der 

Blute. Sitzber. K. Bohm. Ges. Wiss. Math. nat. Kl., 1896: 1-91. 
Darwin, C. 1812. The Origin of Species. 6th London Edition. 
DeBeer, G. R. 1951. Embryos and Ancestors, Revised Edition. Oxford 

University Press. 
Douglas, G. E. 1957. The inferior ovary. II. Bot. Rev., 23: 1-46. 
Eames, a. J. 1931. The vascular anatomy of the flower, with refutation of 

the theory of carpel polymorphism. Amer. J. Bot., 18: 147-188, 
. 1961. Morphology of the Angiosperms. New York: McGraw 

Hill. 
Heel, W. A., van. 1966. Morphology of the androecium in the Malvales. 

Blumea, 13: 177-394. . 
Herr, J. M., Jr. 1971. A new clearing-squash technique for the study of 

ovule development in angiosperms. Amer. J. Bot., 58: 785-790. 
HiEPKo, P. 1965. Das zcntrifugale Androecium von Paeonia. Ber. deu. bot. 

Ges., 77: 427-435. 
HuETHER, C. A., Jr. 1968. Exposure of natural genetic variability under- 
lying the pentamerous corolla constancy in Linanthus androsaceiis ssp. 

androsaceus. Genetics, 60: 123-146. 
Kaplan, D. R. 1967. Floral morphology, organogenesis and interpretation 

of the inferior ovary in Downingia bacigalupii. Amer. J. Bot., 54: 

1274-1290. 
. 1971. On the value of comparative development in phylo- 

genetic studies — a rejoinder. Phytomorphology, 21: 134-140. 



1973 ANGIOSPERMS 19 

Leins, p. 1964. Die fiiihe Bliitcnentwicklung von Hypericum hookerianum 

Wight ct Arn. iind H. aegypticum L. Ber. deu. bot. Ges., 77: 112-123. 
. 1971. Das Androccium der Dicotylen. Ber. deu. bot. Ges., 84: 

191-193. 
Melville, R. 1962. A new theory of the angiosperm flower: 1. The 

gynoeciutn. Kcw Bull.. 16: 1-50. 
MuRBFCK. S. 1914. ubci die Baumcchaiiik bei Andeiungen ini Zahlen- 

veihiiltnis der Bliite. Lunds Univ. Arsskr., N.F., Afd. 2, 11(3): 1-36. 
Olson. K. C, V. W. Tibbits, and B. E. Struckmeyer. 1969. Leaf histo- 
genesis in Lactuca sativa with emphasis upon laticifer ontogeny. Amcr. 

J. Bot., 56: 1212-1216. 
Purl V. 1951. The role of floral anatomy in the solution of morphological 

problems. Bot. Rev., 17: 471-553. 

. 1952. Placentation in angiosperms. Bot. Rev., 18: 603-651. 

RoBSON, N. K. B. 1972. Evolutionary recall in Hypericum (Guttiferae) ? 

Trans, bot. Soc. Edinburgh, 41: 365-383. 
Stebbins, G. L. 1937. Critical notes on Lactuca and related genera. J. Bot., 

75: 12-18. 
. 1940. Studies in the Cichoricae: Dubyaea and Snroseris, 

endemics of the Sino-Himalayan Region. Mem. Torrey bot. Club, 19: 

1-76. 
. . 1950. \'ariation and Evolution in Plants. New York: 



Columbia l^niversit-v Press. 643 pp. 

1967. Adaptive radiation and trends of evolution in higher 



plants. In Evolutionary Biology. Ih. Dob74ian.sky, M. K. Hecht, and 

Wm. C. Steere, eds. \\A. 1: 101-142. 
SwAMv, B. G. L. 1949. Further contributions to the anatomy of the 

Degeneriaceae. J. Arnold Arb., 30: 10-38. 
Thomas, H. H. 1925. The Caytoniales, a new group of angiospermous 

plants from the Jurassic rocks of Yorkshire. Phil. Trans, roy. Soc. 

London, B, 213: 299-313. 
. . 1933. On some pteridospermous plants from the Meso- 

zoic rocks of South Africa. Phil. Trans, roy. Soc. London, B, 222: 193-265. 
Torrey, J. G. 1955. On the determination of vascular patterns during 

tissue differentiation in excised pea roots. Amer. J. Bot., 42: 183-198. 
. 1957. On the determination of vascular pattern formation 

in regenerating pea root meristems grown in vitro. Amer. J. Bot., 44: 

859-870. 
Wetmore, R. H., and J. P. Rier. 1963. Experimental induction of vascular 

tissues in callus of angiosperms. Amer. J. Bot., 50: 418-429. 
Wilson, C. L. 1965. Ihe floral anatomy of the Dilleniaceae. I. Hibbertia 

Andr. Phytomorphology, 15: 248-274. 



B R E XJ.n R A 



LIBRARY 



Miiseiiiii of Comparative Zoology 

JAI^Y 1974 ^^ 

us ISSN 0006-9698 

HQ 

Cambridge, Mass. 28 December .l9|-% Number 419 

PROTOPTYCHUS, A HYSTRIGOMORPHOUS 

RODENT FROM THE LATE EOCENE 

OF NORTH AMERICA 



John H. Wahlert^ 

Abstract. The North American late Eocene Protoptychus Scott possesses 
an enlarged infraorbital foramen, a depression on the side of the snout 
anterior to this foramen for the origin of the anterior part of the middle 
masseter, tetralophate P*-M^ an enlarged incisive foramen, a deep pterygoid 
fossa, and apparently no stapedial foramen or carotid canal. These char- 
acters also occin- in the Caviomorpha. With regard to the zygomasseteric 
structure and acquisition of an essentially molariform P^, Protoptychus is 
more advanced than both its possible North American ancestor, which may 
be either a paranlyid or Mysops, and Platypittamys, the most primitive 
Deseadan (Oligocene) caviomorph. The Protoptychidae, on present evi- 
dence, cannot be related closely to any rodents other than these. Pending 
further knowledge, the family is retained in the Protrogomorpha, but the 
possibility exists that it may be a specialized offshoot from the North 
American caviomorph ancestry. 

Introduction 

In the course of studying the cranial foramina of North 
American protrogomorphous and sciuromorphous rodents, I ex- 
amined the type skull of Protoptychus (Princeton University 
11235) and a second, much damaged facial region (PU 11230). 
I was immediately struck by features that set this form com- 
pletely apart from all others I had at hand. These were the 
unusual shape and great posterior extent of the incisive foramen, 
the large size of the infraorbital foramen, the flatness of the sides 

^American Museum of Natural History, Vertebrate Paleontology Depart- 
ment, Central Park West at 79th Street, New York, N.Y. 10024 



2 BREVIORA No. 419 

of the snout, and the depression of an area on the snout anterior 
and extending somewhat dorsal to the infraorbital foramen. I 
was led, finally, to conclude that Protoptychus is a primitive 
hystricomorphous rodent possibly allied to the ancestry of the 
South American Caviomorpha. The lower jaw is present in 
specimens that I have not seen which belong to the Field Mu- 
seum of Natural History; TurnbuU (personal communication) 
is in the process of preparing these for description. 

Taxonomic History of Protoptychus 

The monotypic genus Protoptychus has had a checkered his- 
tory in the literature of rodent taxonomy. Scott, in describing 
the skull of Protoptychus hatcheri from the Uinta deposits of 
Utah, stated: "That Protoptychus is an ancestral form of the 
Dipodidae seems abundantly clear." 'Tt is not improbable that 
the Heteromyidae were derived from some form related to Pro- 
toptychus, though not from that genus itself" ( 1895 : 280, 286) . 
Matthew (1910: 68) followed Scott in associating the genus 
with the Dipodidae. Schlosser (1911: 427) created the sub- 
family Protoptychinae as one of two di\isions of the family he 
termed Geomyoidea. Miller and Gidlev (1918: 443) placed 
the subfamily back in the Dipodidae. Wood (1935: 239-240) 
stated that the tooth structure did not indicate close relationship 
to the Geomyoidea, and he noted that Schaub's studies on the 
jumping mice and dipodids eliminated them also as relatives of 
Protoptychus. He suggested that, instead, ". . . Protoptychus 
may represent an aberrant and sterile offshoot of the Ischyro- 
mvidae." Wood (1937: 261) formally raised the taxon to 
familial rank, Protoptychidae, as a division of the Ischvro- 
myoidea. Simpson (1945: 78) and Wilson (1949: 99-100) 
followed Wood's familial designation and placement of the 
genus. A diagnosis of the family was published bv Wood in 
1955 (p. 171). 

Dentition 
Figure 1, a and b 

In most respects Scott's description of Protoptychus hatcheri 
(1895) is accurate, but there are a few points that require re- 
consideration. He failed to notice the presence of a minute, 
peglike third premolar, and the revised dental formula (as noted 



1973 



PROTOPTYCHUS 




a 



7 mm 






d 



Figure 1. Dentition of Protoptychus hatcheri (PU 11235) : a. left cheek 
teeth, view perpendicular to wear surface; b. left incisor, cross section. 
Dentition of Mysops parvus (USNM 18043) : c. left cheek teeth, view per- 
pendicular to wear surface; d. left incisor, cross section. 



by Wilson, 1937: 450) is thus P C ?' M\ P'-M' are bra- 
chyodont and notably higher crowned lingually than labially; 
although quite worn, they are clearly four-crested (Fig. la). 
The most conspicuous feature of the crown is a mesoflexus, 
which is broadest at the labial side and ends, at this stage of 
wear, near the middle of the tooth. The crowns of M^"^ are 
grooved in the middle of the lingual side, the groove fading 
away well before reaching the base of the enamel; P* possesses 
only a vague suggestion of this groove. 

Although the four molariform cheek teeth are lophate, the 
cusps are still readily compared with those in paramyid teeth as 
figured by Wood (1962: 8, fig. lA). On the labial side the 
paracone and metacone flank the mesoflexus. The protocone is 



4 BREVIORA No. 419 

anterior to the lingual groove, and the hypocone, posterior; the 
crown is quadrate in outline. The paracone and protocone form 
the protoloph; the metacone and hypocone, the metaloph. The 
hypocone and protocone are already joined in the slightly worn 
M^, and the metaloph is more broadly connected with the hypo- 
cone than with the protocone. A small, low mesostyle is present 
on the molars and is closely associated with the metacone in the 
first molar and with the paracone in the second and third 
molars; it increases in size posteriorly. No trace of it is to be 
seen in P^. The four molariform cheek teeth possess both an 
anteroloph and a posteroloph. These are subordinate in im- 
portance to the two main crests on M^"", and are nearly equal 
to them in prominence in M^. 

Scott remarked ( 1895 : 270) that "the transverse crests visible 
on M^ of Protoptychus (and doubtless in the unworn state of 
the other teeth, also) have a certain resemblance to the teeth of 
squirrels and spermophiles . . . ." In this he is correct because all 
retain in the upper dentition a relatively primitive arrangement 
of cusps. He continued, "... but the fundamental character of 
the tooth pattern is given by the enamel invaginations, which 
tend to di\'ide it into two prisms. This arrangement is most like 
that found in Pedetes, the Heteromyidae and Geornyidae." The 
mesoflexus, however, is not an invagination of the enamel from 
the lingual side of the tooth, it is simply a valley in the enamel 
between two worn crests; the crown is not divided into two 
prisms. 

The incisor enamel as seen in a peel from the transverse break 
appears to be pauciserial. Pauciserial and multiserial enamels 
are similar, and a transverse section is not ideal for distinguish- 
ing them; the enamel is certainly not uniserial. Scott did not 
figure the incisor in cross section; the distribution of enamel 

Figure 2. Skull of Protoptychus hatcheri (PU 11235); dorsal, lateral, and 
ventral views; sutures diagrammatic. 

Key: stippled areas: bone missing, crushed, or matrix covered; dark area 
on snout: site of origin of masseter medialis; hatched areas: cross section 
of bone; dashed lines: structine reconstructed. 

Bones: ah — auditory bulla, as — alisphcnoid. / — frontal, ip — interpari- 
etal, / — jugal. ^ — lachrymal, /// — maxilla, nist — mastoid, // — nasal, 
occ — occipital, as — orbitosi^henoid, p — parietal, pi — palatine. /;/// — 
premaxilla, sq — squamosal. Foramina: bf — buccinator, // — interorbital, 
iof — infraorbital, isj — incisive, ;/ — jugular, tnj — masticatory, o/ — optic, 
paj — post-alar fissure, plj — palatine, sj — stylomastoid. 



1973 



PROTOPTYCHUS 





<^:..I^.^ 




1 cm 



6 BREVIORA No. 419 

on its front surface (Fig. lb) is similar to that in many small 
Eocene rodents, e.g., some species of Paramys, and of Franimys, 
Sciuravus, and Adysops. In transverse section the front of the 
incisor is less bowed than in these forms and has a marked 
posterolateral slant relative to the sagittal plane; it resembles the 
incisor of Platypittamys in this respect. 

Skull 
Figure 2 

Scott's description of the skull is adequate and accurate for the 
most part, but a few additional points can be made. The pos- 
terior extension of the nasal bones almost as far back as the 
middle of the orbits is, to my knowledge, unique to Protoptychus 
among rodents. 

The auditory region is greatly inflated, and both the temporal 
and mastoid portions of the skull participate in this inflation. 
Scott stated that the "... mastoid bulla ... is divided by partial 
septa into chambers, two of which are plainly shown, e\'en ex- 
ternally, being bounded by deep grooves" (1895: 275). The 
two \dsible septae are seen o-nly at the surface, and their extent 
is unknown. The region closely resembles that in Chinchilla 
except that there is no trace of a supraoccipital process that 
reaches the squamosal. In Chinchilla partial septae are present 
in the epitympanic sinus. 

The parietal overlaps the dorsal epitympanic sinus laterally, 
and a narrow process of the parietal extends posteriorly beside 
the interparietal, apparently reaching the mastoid. Scott's dorsal 
view of the specimen (p. 270, fig. 2) shows the process arising 
from the parietal, although he incorrectly states in the text that 
the squamosal "... appears to send out a process between the 
parietal and the mastoid, which articulates with the interparietal" 
(1895: 276). The compression of the posterior part of the 
parietal and the unusual rectangularity of the interparietal seem 
to be in response to the great dorsal inflation of the epitympanic 
sinus. The back of the skull roof retains the primiti\e flatness 
and sharp angle with the occipital surface; it does not curve 
downward onto the occipital surface as it does in dipodids, 
heteromyids, and those caviomorphs in which the auditory region 
is also greatly inflated. 

Many of the cranial foramina are preserved in the type speci- 
men. The incisive foramina, unlike those of any protrogomor- 



1973 PROTOPTYCHUS 7 

phous rodent, are unusually long, extending back to the middle 
of the fourth premolar, and their lateral margins are intersected 
anterior to the middle by the premaxillary-maxillary suture. 

The infraorbital foramen is conspicuously larger dorsoventrally 
than that of any protrogomorphous rodent. The sides of the 
snout are flattened, and the course of the incisor root stands out 
as a swelling. Just anterior to the infraorbital foramen and ex- 
tending somewhat dorsal to it is a depression on the side of the 
snout; this area appears to have been the site of origin of the 
anterior part of the medial masseter, which must have passed 
through the infraorbital foramen. Protoptychus was hystri- 
comorphous. 

In the orbital region, three foramina are visible. The optic 
foramen, of which only the ventral margin remains, is clearly a 
large aperture in comparison with those of paramyids, and is 
probably the structure which Scott (1895: 278) called "a large 
sphenoid fissure." Antero ventral to the optic foramen in the 
orbitosphenoid is a small aperture, possibly an interorbtial fora- 
men. A foramen occurs in this position in various unrelated 
rodents, e.g., Ischyromys, Geomys, and questionably in Castor, 
and I attach no special taxonomic significance to its presence 
here. In the floor of the orbit is a dorsal palatine foramen, which 
transmitted the descending palatine artery. In Paramys this fora- 
men shares a common opening with the sphenopalatine, whereas 
in Protoptychus, as in Sciuravus, the foramen is in the orbital 
floor posterolateral to the sphenopalatine foramen. The posterior 
palatine foramen, the exit for the artery, is wholly within the 
palatine, the primitixe condition for rodents. 

The margin of the sphenoidal fissure and most of the region 
where the aHsphenoid, parietal, frontal, and orbitosphenoid come 
close together is crushed. The masticatory and buccinator fora- 
mina open upward and forward, respectively, near the back of 
the alisphenoid bone. Retention of separate foramina for the 
masseteric and buccinator nerves is a primitive rodent character. 
Posterior to the buccinator foramen there is an emargination of 
the alisphenoid, which, with the anterior side of the bulla, makes 
a foramen. A multiple aperture in the position is present in 
Reithroparamys; there is no comparable foramen in other para- 
myid skulls or in Sciuravus. 

The postglenoid and the temporal foramen are absent, prob- 
ably because of the greatly inflated bullae. The stapedial fora- 
men, carotid canal, and mastoid foramen appear to be absent. 



8 BREVIORA No. 419 

but they (especially the last two) may have been obliterated 
by the slight lateral crushing which the specimen has suffered. 
The pterygoid fossa is very deep, and inadequately preserved 
for full description. 

Discussion 

By the process of elimination it is possible to rule out relation- 
ship to any rodent group except the Paramyidae, the genus 
Alysops, and the Ca\'iomorpha. Of the protrogomorphous ro- 
dents, all but the Paramyidae and Mysops are significantly dif- 
ferent from Protoptychus. 

In 1959 Wood (p. 359) thought that the Protoptychidae 
might have been deri\'ed from the Sciuravidae; sciuravids are 
primiti\e in most skull characters and in this respect could be 
ancestral. However, the cheek teeth and their incipient crests 
are not nearly so primitive. Unlike the condition in Protoptychus 
and paramyids, the medial valley of the crown is open lingually 
and blocked labially by the mesostyle. Wilson (1949: 91) noted 
this and other characteristics of the cheek teeth as being markedly 
different from those of most paramyids. 

The cheek teeth of Protoptychus are advanced over those of 
paramyids in that the third premolar is greatly reduced, the 
fourth premolar and third molar are tetralophate, and the 
metaloph is more closely connected with the hypocone than with 
the protocone. The major cusps, howe\ er, are still readily identi- 
fiable, and the anteroloph and posteroloph are not quite equal in 
prominence to the crests formed by these cusps. The basic pat- 
tern is most nearly comparable to that of Paramys and Reithro- 
par amy s. Some reduction of the third premolar has already 
occurred in Reithro paramys. Wood (1962: 248) tentatively 
suggested derivation of Protoptychus from Reithro paramys but 
stated, "On the other hand there are some undescribed specimens 
(including skeletons) that seem to suggest other relationships 
for Protoptychus-" These remain undescribed. 

The cheek teeth of the Ischyromyidae (including only 7^- 
chyromys and Titanotheriomys) are very similar. However, the 
infraorbital foramen is much smaller, and the zygomatic plate is 
tilted, indicating a trend toward a sciuromorphous type of masti- 
catory musculature\ The dorsal palatine foramen is well inside 

^Having examined the evidence, I agree with Wood (1937: 195) rather 
than Black (1968: 275) on this point. 



1973 PROTOPTYCHUS 9 

the sphenopalatine foramen; the pterygoid fossa, though well 
developed, is not nearly so deep; and there is a well-defined caro- 
tid canal in ischyromyids. 

The cylindrodontids\ specifically Ardynomys, which has four- 
crested cheek teeth, differ in detail. The dorsal palatine foramen 
is not separated from the sphenopalatine; the pterygoid fossa is 
shallow, and the carotid canal is present although small. 

The Eocene rodent that most closely resembles Protoptychus 
is Mysops. There are three differences between the molariform 
teeth of the two genera (cf. Fig. Ic and d). In Mysops the 
anteroloph of P^ is not fully developed as a continuous crest; 
the metaloph is incomplete and does not meet the hypocone, 
though its trend is toward the anterior part of that cusp; and 
whereas in Protoptychus the cusp is prominent, in Mysops it is a 
very minor one. As seen in transverse section, the incisors of 
Mysops are very similar to those of Protoptychus, but the an- 
terior surface is more bowed. The alveolus for P^ indicates that 
in Mysops the tooth was not reduced. A striking bit of evidence 
for relationship between the two genera is that in Mysops the 
length ratio of the incisive foramina to diastemal length exceeds 
.60, a ratio greater than that known for any protrogomorphous 
rodent (Wahlert, 1972). x\lthough the foramina do not extend 
as far back as the first premolar, as in Protoptychus, their size 
suggests a stage intermediate between a paramyid or sciuravid 
and Protoptychus. 

The Aplodontoidea, even the earliest ones, are so different in 
cusp pattern that close relationship to them can be ruled out. 
Prosciurids, which are most likely ancestral to aplodontoids, 
differ in the same regard. In them the pterygoid fossa is not 
deep, and there is a conspicuous stapedial foramen. 

There is nothing about the dentition of Protoptychus that sug- 
gests relationship to the Hystricidae, which, to judge from their 
geologic record, mav have been of Oriental origin (Wood and 
Patterson, 1970: 636). 

The phiomyids, most notably Metaphiomys, bear some sim- 
ilarity to Protoptychus in that they are hystricomorphous and 
also have enlarged incisive foramina (Wood, 1968). The cheek 

l^Vilson {e.g., 1949: 93) and Wood (personal communication) , on the 
basis of dental similarity, place Mysops in the Cylindrodontidae. I hesitate 
to accept this assignment because, in the one partial skull of the genus 
(USNM 18043) , the incisive foramina are considerably longer relative to the 
diastemal length than in Cylindrodon, Pseudocylindrodon, and Ardynomys. 



10 BREVIORA No. 419 

teeth, however, are quite different; the crown pattern of Pro- 
toptychus is four-crested, whereas those of Phiomys and Meta- 
phiomys are five-crested, the fifth crest being the mesoloph. Like- 
wise the cheek teeth of the theridomyids differ in having five 
crests. 

Myomorphous rodents can be excluded from possible relation- 
ship because the cheek tooth cusp pattern is essentially different. 
All sciuromorphous forms can be eliminated because of their 
zygomasseteric structure. Furthermore, the stapedial artery, 
which may well have been lacking in Protoptychus, is retained 
and its foramen is conspicuous in heteromyids and eomyids; in 
sciurids the foramen is present although less easily seen. 

The remaining group for consideration is the Caviomorpha. 
The Caviomorpha are hystricomorphous ; many of the early 
South American members of the group, e.g., the Deseadan 
Cephalomys (Wood and Patterson, 1959: 343, fig. 21), Sal- 
lamys and Incamys (Patterson and Wood, in preparation), and 
se\eral Santacruzian genera illustrated in Scott ( 1 905 ) have 
elongate incisive foramina. The living caviomorphs lack the 
tympanic portions of both the stapedial and internal carotid 
arteries (Guthrie, 1963: 478; Bugge, 1971: 532), as is quite 
possibly the case in Protoptychus. The pterygoid fossa is \'ery 
deep in caviomorphs. 

The cheek teeth of Protoptychus are lophate and are based 
on a series of four crests that are fully homologous with those of 
primitive caviomorphs. Protoptychus retains a small but distinct 
mesostyle on the molars which is lacking in caviomorphs, except 
Branisatnys luribayensis, which has the cuspule on the second 
molar (Hoffstetter and Lavocat, 1970: 172 and fig.); it lacks 
the lingual valley, the hypoflexus, which is prominent in cavio- 
morphs, but does have an indentation in that position. The 
fourth premolar of Protoptychus is molariform, unlike those of 
the more primitive Deseadan caviomorphs, Deseadomys, and 
Platypittamys, but shows some resemblance to one specimen of 
Sallarnys (Patterson and Wood, in preparation). 

The incisors, as noted above, appear to have pauciserial 
enamel. This is a plausible condition for a caviomorph relative, 
since multiserial enamel was surely derived from pauciserial 
( Korvenkontio, 1934; Wahlert, 1968: 13), and the two are not 
very different, bands of the inner enamel layer in each being 
several prisms wide. 

The simplest taxonomic interpretation of Protoptychus is to 



1973 PROTOPTYCHUS 11 

call it a hystricomorphous member of the Protrogomorpha. 
Structural details which are like those found in caviomorphs 
would be attributed either to convergence or to parallelism stem- 
ming from common ancestry within the Protrogomorpha. The 
consequence of this interpretation would be that the hystrico- 
morphous condition of the masseter and infraorbital foramen 
arose more than once from the protrogomorphous condition, a 
conclusion in keeping with the similar multiple origin of sciuro- 
morphous musculature, e.g., independently in Titanotheriomys, 
and with its presence as a component of the myomorphous con- 
dition. Mysops may be a close relative of Protoptychus, but until 
a good skull of the genus is known this can be taken as no more 
than a possibility. The specialized characteristics of Protopty- 
chus, especially those associated with the masseter and with the 
auditory region, confirm the need for a separate family to receive 
the genus. 

Protoptychus could be a caviomorph, but, on the basis of the 
earliest forms known, a rather complicated explanation would 
be required. There are three anatomical barriers to placing 
Protoptychus in the Caviomorpha: its precociously molariform 
[i.e., four-crested ). fourth premolar, the lack of a distinct hypo- 
flexus in the molars, and its hystricomorphous condition. Ac- 
cording to Wood (1949) the most primitive Deseadan cavio- 
morph^, Platypittamys, has only a slightly enlarged infraorbital 
foramen, which did not transmit any part of the masseter, and 
a simpler fourth premolar than any paramyid known at the time 
of its description; whether the condition of the premolar was 
primitive or reduced could not be determined. On the basis of 
an undescribed Gray Bull paramyid. Wood and Patterson 
(1959: 296-297) were able to ascertain that the absence of a 
separate metaloph in the fourth premolar of Platypittamys and 
some other Deseadan caviomorphs is primitive. The Gray Bull 
paramyid, Franimys, was described by Wood in 1962 (pp. 139- 
147). The fourth premolar is comparable and also simple. 

Although the cheek tooth patterns of Protoptychus are closer 
to those of Paramys, Reithroparamys, and Mysops, it is possible 
to derive them from that of Franimys. The direct ancestor of 
the South American Caviomorpha would then have been primi- 

^The caviomorphs described by Hoffstetter and Lavocat (1970) from the 
Deseadan of Bolivia are more advanced in that they already have enlarged 
infraorbital foramina and the posteroloph in some is divided into two parts 
(I do not agree that a mesoloph is present) . 



12 BREVIORA No. 419 

tive in comparison with its closely related North American con- 
temporaries. Wood and Patterson (1959: 406) stated, "The 
South American rodents were not descended from immigrants 
from Wyoming, but rather from rodents that lived in some part 
of middle America or southeastern United States, regions from 
which the Eocene mammalian faunas are essentially unknown." 
The rarity of Protoptychus in fossil collections supports the pos- 
sibility that it, too, is based in a stock e\^olving elsewhere than 
in the western United States. 

Until the lower jaw of Protoptychus is described, however, 
retention of the hystricomorphous Protoptychidae in the Pro- 
trogomorpha seems advisable for the present, since a hystri- 
comorphous skull can accompany a sciurognathus jaw [e.g., 
Pedetes). The similarities to caviomorphs are very suggestive 
nevertheless. The future may reveal that Protoptychus was a 
precociously specialized offshoot of the northern group from 
which ca\'iomorphs arose. 

ACKNOW^LEDGMENTS 

I am indebted to Albert E. Wood and Brvan Patterson for 
their guidance; to the vertebrate paleontology staff at Princeton 
University for permitting me to study the specimens; and to 
Barbara Lawrence and Charles Mack of the Mammal Depart- 
ment, Museum of Comparati\'e Zoology, for making modern 
comparati\'e material available to me. I would also like to 
thank both Carol C. Jones for unbiased corroboration of my 
views of structural details, and Katherine H. Wahlert for aid 
with the manuscript. 

References 

Black, C. C. 1968. The Oligocene rodent Iscliyromys and discussion of the 
family Ischyromyidae. Ann. Carnegie Mus., 39: 273-305. 

BuGGE, J. 1971. The cephalic arterial system in New and Old World 
hystricomorphs, and in bathyergoids, with special reference to the sys- 
tematic classification of rodents. Acta Anat., 80: 516-536. 

Guthrie, D. A. 1963. The carotid circulation in the Rodentia. Bull. Mus. 
Comp. Zool., 128: 455-481. 

HoFFSTETTER, R., AND R. Lavocat. 1970. Decouvcrte dans le Deseadien de 
Bolivie de genres pentalophodontes appuyant les affmites africaines des 
Rongeurs Caviomorphes. Compt. Rend. Acad. Sci. Paris, Ser. D, 271: 
172-175. 



1973 PROTOPTYCHUS 13 

KoRVENKONTio, V. A. 1934. Mikroskopische Uiitcisucluingcn an Nagerin- 

cisiven, unter Hinweis auf die Schmelzstiuktur dcr Backenzahne. Ann. 

Zool. Soc. Zool.-Bot. Fcnnicae Vanamo, 2: i-xiv, 1-274. 
Matthew, W. D. 1910. On the osteology and relationships of Paramys, 

and the affinities of the Ischyiomyidae. Bull. Amer. Mus. Natur. Hist., 

28: 43-72. 
Miller, G. S., and J. W. Gidley. 1918. Synopsis of the supcigeneric 

groups of rodents. Jour. Washington Acad. Sci., 8: 431-448. 

ScHLOSSER, M. 1911. Mammalia Saugetiere, p. 325-585. In K. A. von 

Zittel, Grundziige der Paliiontologie, II Abt. — Vertebrata; neubearbeitet 

von F. Broili, E. Koken, M. Schlosser. Munich and Berlin: R. Olden- 

bourg. 
Scott, W. B. 1895. Protoptychus hatcheri, a new rodent from the Uinta 

Eocene. Proc. Acad. Natur. Sci. Philadelphia, 1895: 269-286. 
1905. Paleontology. Part III. Glires. Repts. Princeton 

Univ. Exped. Patagonia, 5: 384-487, plates LXIV-LXX. 
Simpson, G. G. 1945. The principles of classification and a classification of 

mammals. Bull. Amer. Mus. Natur. Hist., 85: 1-350. 
Wahlert, J. H. 1968. Variability of rodent incisor enamel as viewed in 

thin section, and the microstructure of the enamel in fossil and Recent 

rodent groups. Breviora, No. 309: 1-18. 
1972. The cranial foramina of protrogomorphous and 

sciuromorphous rodents; an anatomical and phylogenetic study. Ph.D. 

Thesis. Harvard Univ. 230 pp. 
Wilson, R. W^. 1937. Two new Eocene rodents from the Green River 

Basin, Wyoming. Amer. Jour. Sci., 34: 447-456. 
. 1949. Early Tertiary rodents of North America. Carnegie 

Inst. Washington Pub., 584: 67-164. 
Wood, A. E. 1935. Evolution and relationships of the heteromyid rodents. 

Ann. Carnegie Mus., 24: 73-262. 
. 1937. Rodentia, pp. 155-269. In W. B. Scott, G. L. Jepsen, 

and A. E. Wood, The mammalian fauna of the White River Oligocene. 

Trans. Amer. Phil. Soc. (n.s.) , 28. 
. 1949. A new Oligocene rodent genus from Patagonia. Amer. 



Mus. Novitates, No. 1435: 1-54. 
1955. A revised classification of the rodents. Jour. Mammal., 



36: 165-187. 
. 1959. Eocene radiation and phylogeny of the rodents. Evo- 



lution, 13: 354-361. 
. 1962. The early Tertiary rodents of the family Paramyidae. 



Trans. Amer. Phil. Soc. (n.s.) , 52: 1-261. 

1968. Early Cenozoic mammalian faunas, Fayum Province, 



Eg)pt. Part II. The African Oligocene Rodentia. Bull. Peabody Mus. 
Natur. Hist., 28: 23-105. 



14 BREVIORA No. 419 
, AND B. Patterson. 1959. The rodents of the Deseadan Oli- 



gocene of Patagonia and the beginnings of South American rodent evolu- 
tion. Bull. Mus. Comp. ZooL, 120: 281-428. 
, AND . 1970. Relationships among hystritognath- 



oiis and hystricomorphous rodents. Mammalia, 34: 628-639. 

Addendum 

Since this manuscript was submitted, W. D. Tumbull (per- 
sonal communication) has pro\ided me with a description of 
the lower jaw in a Field Museum specimen of Protoptychus; 
only the outside of the jaw has been prepared so far. Turnbull 
states, "The masseteric fossa of the lower jaw is distinct but 
shallow, and the angle is laterally offset and rather attenuated. 
From the offset angle and the appearance of the junction of the 
angle with the ramus, Fd say it had a well developed pars 
reflexa to the masseter, but I'\'e not seen the medial side so 
know nothing about its area of insertion." He concludes that 
the jaw was probably quite hystricognathus. This evidence adds 
support to the hypothesis that Protoptychus is related to the 
caviomorph rodents through common ancestry either within the 
paramyids or within a Middle American caviomorph population 
that is as vet unknown. 




B R E V I a^fipA 

Museum of Comparative 

us ISSN 0006-9698 

Cambridge, Mass. 29 March 1974 iiNiV^'^'^^fi^^^ 

ENVIRONMENTAL FACTORS CONTROLLING 

THE DISTRIBUTION OF RECENT 

BENTHONIC FORAMINIFERA 

Gary O. G. Greiner* 

Editorial Introduction 

Gary Greiner lost an eight-year battle with cancer and died 
in January 1973 at the age of 31. His unconventional approach 
to paleontology belied the painfully shy and unassuming charac- 
ter that many might have taken, so wrongly, as marks of merely 
ordinary ability. He was an original and radical thinker, limited, 
frustrated, even exasperated, by the reception that must attend 
unconventional ideas (be they right or wrong). And it was his 
special tragedy that illness, with its ultimate and ineluctable re- 
sult, struck even before he began his research and robbed him of 
energy and time to test the ideas that flowed so readily. 

Gary was captivated by D'Arcy Thompson's approach to 
form — ■ to the reduction of organic complexity to a few, simple 
generating factors related to physical forces in the environment. 
D'Arcy Thompson overstated his case for the complex Metazoa, 
but it represents an insight scarcely explored (though surely 
more appropriate) for simpler Foraminifera. Gary asserted this 
theme within a traditional area of natural history fundamentally 
hostile to it ( f or amini feral systematics) ■ — an area that cata- 
logues the specific, the unusual and the peculiar in preference to 
extracting the simpler regularities that have both general sig- 
nificance and frequent exceptions. 

This paper represents Gary's views on the control of relative 
abundances by a simple environmental factor. Specialists will 
recognize some exceptions among forams in other parts of the 

♦Request reprints from Stephen Jay Gould, Museum of Comparative 
Zoology, Harvard University, Cambridge, Mass. 02138. 



2 BREVIORA No. 420 

world. They may disagree with his unsupported speculations on 
the significance and mode of formation for different types of 
calcareous walls. Yet the data on distribution are firm and 
must be explained. We hope that readers will focus on the 
power of Gary's unconventional approach, on his search for 
reduction and cause in preference to elaboration and minute, 
thoughtless description. 

As an appendix, we attach the short text of a talk delivered 
to the annual meeting of the Geological Society of America in 
1970. It supplements, in a broader evolutionary context, the 
central notion of physical control so central to the functional 
theme of causal correlation between environment and form. 
We report with the greatest regret that we were unable to re- 
construct Gary's major work from his fragmentary notes and 
copious data — a bold attempt to synonymize virtually all the 
agglutinating Foraminifera of the Gulf of Mexico by showing 
that the entire range of form (now attributed to several genera) 
can be generated automatically by the interaction of a varying 
environment and the few parameters (sensu Raup and Vermeij) 
needed to specify construction of the seemingly complex fora- 
miniferal test. 

Gary wrote the following paper during a post-doctoral year 
at the Museum of Comparative ^oology. It was our privilege 
to have known, better than most others, such a courageous and 
talented person. 

Stephen Jay Gould 
Alan D. Hecht 

Abstract. The relative abundance distributions of the three major groups 
of benthonic Foraminifera (agghitinated, porcelaneous, and hyaline calcare- 
ous) from the northern Gulf of Mexico paralic environments have been 
studied to determine the environmental factor, or factors, actually controlling 
the distribution. The relative contribution of each type to the total fora- 
miniferal fauna is related to temperature and/or salinity within each bay 
studied, and to regional gradients in temperature and salinity (expressions 
of climatic and physiographic interactions) throughout the northern Gulf 
estuaries. 

I conclude that these correlations can be explained on the basis of fora- 
miniferal interaction with a single environmental factor — availability of 
calcium carbonate for use in construction of tests. This factor depends, to 
a large extent, on salinity and temperature in shallow, marine or brackish 
waters. 

Agglutinated Foraminifera do not require calcite to build their test; they 
dominate the faunas in areas of low CaCOg availability. Porcelaneous Fora- 



1974 FORAMINIFERAL DISTRIBUTION 3 

niinifera employ no nucleating surface for cakite crystal growth; crystals 
develop in a random array within a cytoplasmic layer. They dominate in 
areas of high CaCOj availability, but diminish in abundance toward lower 
values owing to difficulties in secretion of calcite. Hyaline calcareous 
Foraminifera produce oriented calcite crystals grown on an organic nucleating 
surface. This surface permits secretion of calcite for test construction in 
areas of lower CaCOj availability than is possible for the porcelaneous types, 
but the need for an ordered structure prevents their thriving in areas of 
hyper-supersaturation. Calcareous Foraminifera can dominate agglutinated 
types when CaCO;. is readily available, through occupation of niches un- 
available to the latter (e.g., on marine plants) . Thus, hyaline calcareous 
Foraminifera dominate in areas of intermediate CaCOg availability. 

If we accept this simplistic approach to the study of Foraminifera. then 
its ramifications might have far-reaching effects in the study of foraminiferal 
paleoecology, since the applications would be independent of specific or 
generic classification. 

Introduction 

Most ecologic studies of Recent Foraminifera have dealt with 
distributions of the various species or genera present in a par- 
ticular area, and with the correlation of these distributions with 
various environmental parameters. The reasons for these corre- 
lations are difficult to ascertain; hence, the applicability to the 
fossil record of conclusions based on such correlations is often 
doubtful. To extend ecological inferences of a particular faunal 
group to paleontologic situations, an understanding of environ- 
mental interactions with morphologic characteristics transcend- 
ing specific or generic classifications should be sought. 

I chose foraminiferal wall type as the character to investigate 
(Greiner, 1969). In standard classifications (Loeblich and Tap- 
pan, 1964), wall type is used to separate the three major groups 
of Foraminifera into suborders — the Textulariina ( agglutinated 
walls), the Miliolina (porcelaneous, calcitic walls), and the 
Rotahina (perforate, hyahne calcareous walls). If the influence 
exerted by the environment on the distribution of these separate 
suborders could be recognized, the information gained could 
reasonably be extrapolated to paleoecologic interpretations of 
faunas as early as the beginning of the Mesozoic Era when cal- 
careous Foraminifera were becoming abundant. 

In the Recent, the relative contributions of each of these 
groups to the total fauna vary systematically across the con- 
tinental shelf, from one bav to another, and from boreal waters 
to the tropics. That these changes are systematic and simple, 
rather than sporadic and complex, suggests that the abundances 



BREVIORA 



No. 420 




1974 FORAMINIFERAL DISTRIBUTION 5 

of the foraniiniferal suborders are being controlled by some 
general property of the environment, and that this property also 
varies simply and systematically. I assumed that a careful analy- 
sis of these distributions in relation to general environmental 
parameters would result in correlations leading to an under- 
standing of the actual controlling factor or factors. Depth, the 
one factor suggested by Phleger (1960a) as most significant 
in controlling distributions of foraminiferal species in offshore 
traverses, can be essentially eliminated from consideration by 
investigation of faunas in very shallow water bodies — bays, 
lagoons, and sounds. Variation in the faunas can then be 
ascribed to some other environmental factor, such as tempera- 
ture, salinity, character of the substrate, or some critical com- 
bination of several of these. 

Foraminiferal faunas and general environmental parameters 
have been described for many of the larger bays, lagoons, and 
sounds adjacent to the northern Gulf of Mexico (Fig. 1). Since 
we have adequate literature on these shallow water bodies and 
since they form a geographic, as well as an environmental, con- 
tinuum, they have been chosen for more complete analysis. 

The purposes of this study are, then, to describe the relative 
abundance distributions of the three major groups of benthonic 
Foraminifera in the estuarine environments of the northern Gulf 
of Mexico; to relate these distributions to physical and chemical 
parameters of the environment; to review the more recent litera- 
ture pertinent to the understanding of physiologic mechanisms 
employed by the foraminifers in constructing each wall type; 
and, finally, to summarize the environmental factors and relate 
them to the physiologic processes of wall construction by these 
protists, with a view to determining the actual causes of distribu- 
tion at this morphologic level. 

The results, it is hoped, will have a general significance for 
the interpretation of the paleoenvironments and paleoclimates 
of geologic epochs prior to those populated by species that still 
exist today. 

Previous Studies of Foraminiferal Ecology 

The early works on Recent foraminiferal ecology {e.g., Parker, 
1948; Phleger and Parker, 1951; Parker, Phleger, and Peirson, 
1953; and Bandy, 1956) were largely taxonomic, with descrip- 
tions of species distribution in relation to depth and geographic 
position, based on relative abundances at each sample locality. 



6 BREVIORA No. 420 

Various environmental parameters were invoked to explain the 
apparent natural breaks in faunal patterns. Since depth and 
proximity to the shore and continental shelf break had been 
measured, and since little else was known about the environment 
of the open ocean, discontinuities in the distributions were cor- 
related with these factors. 

Later studies show similar approaches to the problem of causes 
for the observed distribution patterns. A notable example is that 
of Lidz (1965), who observed intercorrelations of various en- 
vironmental factors and species distributions measured in Nan- 
tucket Bay, Massachusetts. The most that could be said, based 
on the correlations, is that all of the factors are interrelated and 
correlated with one another, i.e., the environmental factors are, 
to varying degrees, dependent variables. But nothing can be 
said about actual causes of the foraminiferal distributions. 

Phleger (1960a), in discussing the ecology and distribution of 
Recent Foraminifera, states that the causes of depth zonation 
and other distribution patterns are not clearly known. The fac- 
tors involved (he states) are temperature, salinity, food, water 
chemistry, pressure, currents, turbidity, turbulence, substrate, 
biologic competition, disease, etc. And in summarizing this long 
list, he states that at the present state of our knowledge it is not 
possible to evaluate any one of these factors. In a later report 
of the state of the field (Phleger, 1964), he indicates that 
". . . there is little or no specific information on the interactions 
between the patterns of benthonic foraminiferal faunas and the 
natural environments which control these patterns." 

A few, more current papers reflect this state of aflfairs and 
illustrate attempts to define characteristics of foraminiferal popu- 
lations (diversity, planktonic/benthonic ratios, general morphol- 
ogy, etc.) which transcend specific or generic characteristics and 
which are explicable in terms of the environment (Bandv and 
Arnal, 1960; Bandy, 1964; Phleger, 1964; Stehh, 1966; Want- 
land, 1967). 

Funnell (1967) summarizes our knowledge of foraminiferal 
ecology in a discussion of Foraminifera as depth indicators in the 
marine en\'ironment. He suggests that since Foraminifera are 
studied with relation to depth, and depth has so many factors 
correlated to it, we can construct good interpretations for the 
Tertiary of, say, the Gulf Coast as compared to the Recent Gulf 
of Mexico, but that these same conclusions will not be neces- 
sarily valid for the Tertiary of, for example, northwestern 
Europe, or for the pre-Tertiary of the Gulf Coast. 



1974 



FORAMINIFERAL DISTRIBUTION 





January 



April 





July 



October 



MEAN SURFACE TEMPERATURES (°F) 

for the 

GULF OF MEXICO 



Figure 2. Mean surface water temperatures during four months of the 
year for the Gulf of Mexico. (Redrawn from charts supplied by the National 
Oceanographic Data Center, 1966.) 



Clearly then, the causes of various trends in foraminiferal 
faunas must be established, if situations in the fossil record fun- 
damentally dissimilar to the time or area of Recent investigations 
are to be treated profitably. 

Physigo-Chemical Setting of the Gulf of Mexico 

The coastal United States bordering the northern Gulf of 
Mexico is generally a broad, low-lying plain. The near-shore, 
shallow-water environments are made more complex by the 
presence of many barrier islands closely paralleling the coastline 
and often restricting the free interchange of river and open Gulf 
waters. The presence of the barrier islands produces many bays, 
lagoons, and sounds ( Fig. 1 ) , which harbor faunas distinct from 
those of the open Gulf. The temperatures and salinities of the 
water in these estuarine environments are a result of the inter- 
action of various climatic and physiographic parameters of the 
region. 

There is a definite increase in mean annual temperature (re- 



8 



BREVIORA 



No. 420 





Jan.-Mar. 



Apr.-Jun. 





Jul .-Sept. 



Oct.- Dec. 



MEAN SURFACE SALINITIES 
for the 
GULF OF MEXICO 



Figure 3. Mean surface water salinity during four seasons of the year 
for the Gulf of Mexico. (Redrawn from charts supplied by the National 
Oceanographic Data Center, 1966.) 



fleeted in the Gulf surface water temperatures, Fig. 2; and in 
the January normal isotherms of Fig. 9) from north to south 
across the region. Since the bays are generally quite shallow, and 
hence the water well-mixed by wind, temperatures in them tend 
to correspond to air temperatures. Thus, mean annual water 
temperatures in the estuarine environments around the northern 
Gulf are lowest in Mobile Bay-Mississippi Sound and Sabine 
Lake, and increase in the more southern bays, being highest in 
Florida Bay and I^aguna Madre. 

Salinity values in the bays similarly show an increase from 
north to south. This is the result of several interrelated factors 
— precipitation, runoff, evaporation, and salinity of adjacent 
Gulf water ( Fig. 3 ) . The first three factors have been studied 
by Thornthwaite (1948) and the net effect plotted on a map 
as moisture budget isopleths ( reproduced here as part of Fig. 9 ) , 
which are an indication of moisture surplus (positive values) and 
moisture deficit (negative values). In general, low salinity values 
in the bays are associated with high moisture surpluses, as fresh- 
water influx into an enclosed shallow water body prevents, to 



1974 FORAMINIFERAL DISTRIBUTION 9 

varying degrees, the encroachment of higher salinity Gulf water 
{e.g., Mobile Bay-Mississippi Sound and Sabine Lake). (See 
discussion by Phleger, 1954: 604). On the other hand, high 
salinity \'alues are associated with moisture deficiencies. In this 
case the evaporation of lagoonal water permits entrance of higher 
salinity Gulf water and subsequent concentration of dissolved 
salts {e.g., Laguna Madre). The general increase in salinity of 
open Gulf water from north to south (Fig. 3) enhances this 
estuarine environmental continuum of increasing salinity, ob- 
served from Mobile Bay-Mississippi Sound to Laguna Madre 
on the west and to Florida Bay on the east. 

Through the interaction of these climatic and physiographic 
factors, then, an environmental continuum of increasing temper- 
atures and increasing salinities is produced in the shallow water 
bodies under consideration here, from Mobile Bay-Mississippi 
Sound and Sabine Lake with lowest values, through Matagorda 
Bay and San Antonio Bay and environs on the west and Tampa 
Bay and Charlotte Harbour on the east with intermediate values, 
to Laguna Madre and Florida Bay with highest values. 

Discussion of Foraminiferal Distributions 

From published tables of species abundances in various estu- 
arine environments around the northern Gulf of Mexico, I cal- 
culated the relative abundance of individuals possessing each of 
the three major wall types at given sample locations. This is 
based on percentage of individuals in the total (living plus dead) 
foraminiferal fauna. I then plotted these percentages on maps 
of the sample distributions and contoured the values. 

The relative abundance distribution of the three foraminiferal 
groups will be discussed in detail for three of the estuarine en- 
vironments — Mobile Bay-Mississippi Sound, Tampa Bay, and 
Laguna Madre — and more broadly for the others, to demon- 
strate correlations with temperature and salinity on the local 
scale. Following this, I will consider the faunal dominance by 
each of the groups through all the bays, lagoons, and sounds 
adjacent to the northern Gulf to document similar correlations 
with these environmental factors on a regional scale. 

mobile BAY-MISSISSIPPI SOUND 

The distribution of Foraminifera and possible ecologic factors 
affecting the distribution in Mobile Bay, Alabama, have been 
briefly mentioned by Walton ( 1 964 ) . Phleger ( 1 954 ) has made 



10 



BREVIORA 



No. 420 







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1974 FORAMINIFERAL DISTRIBUTION 11 

a similar but more detailed study of the Mississippi Sound. 
Upshaw et al. (1966) have studied and described the environ- 
ment, sediments, and microfauna from both areas plus a portion 
of the adjacent continental shelf (Fig. 4). 

There is a considerable moisture excess for this region 
(Thornthwaite, 1948; and Fig. 9) . This results from many large 
ri\'ei's discharging fresh water into Mobile Bay (Mobile and 
Tensaw rivers) and Mississippi Sound (particularly the Pas- 
cagoula River). The offshore, discontinuous island chain is an 
effective barrier to ready mixing of this runoff with the open 
Gulf water ( Phleger, 1 954 ) . However, some denser, more saline 
water from the Gulf does enter Mississippi Sound by way of the 
surge channels and mixes with the fresh water from the rivers 
within this shallow water body. Thus, there is a steep salinity 
gradient in bottom waters from the open Gulf (with usually 
35°/oo), through the adjacent inlet (near 30° /oo), and into 
Mobile Bay-Mississippi Sound (to < 5°/oo within 10 miles of 
the Gulf). 

From the foraminiferal distribution data of Upshaw et al. 
( 1966, plate 4, reproduced here as Fig. 4), it is evident that the 
agglutinated Foraminifera are relatively most abundant in water 
with the lowest salinity values, and that they decrease in relative 
abundance with increasing salinity. On the other hand, the 
hyaline calcareous Foraminifera are associated with the more 
saline Gulf water, diminishing in relative abundance as it is 
diluted by fresh water within the bay and sound. Representatives 
of the third group, the porcelaneous Foraminfera, are not found 
within this restricted area, though they are present (up to 30% 
or more) in the more saline Gulf water somewhat seaward of 
the freshwater influence. Hence, the relative abundance dis- 
tributions of two of the foraminiferal groups are correlated here 
with water salinity values - — ■ hyaline calcareous directly, ag- 
glutinated inversely. 

TAMPA BAY 

Bandy (1956) and Walton (1964) have made ecologic studies 
of the Foraminifera of Tampa Bay and environs, including Old 
Tampa Bay (Walton, 1964) and Hillsboro Bay (Bandy, 1956). 

Bathymetrically, the bay can be divided into low sand and 
grass flats of shallow depth (< 15 ft. of water) with superim- 
posed relatively deep channels (Goodell and GorsHne, 1960). 
Maximum depth in the bay is slightly more than 30 feet, which 



12 



BREVIORA 



No. 420 



• 2*30' 



28*00 



-27'50 




after Bandy, 1956; and Walton, 1964 



Figure 5. Bathymetry and sample locations for Tampa Bay, Florida. 
(From Bandy, 1956; and Walton, 1964.) 



1974 FORAMINIFERAL DISTRIBUTION 13 

is that of most of the channels ( Fig. 5 ) . The sediments of 
Tampa Bay are predominantly fine to very fine quartz sands 
(Walton, 1964). 

The salinity distribution pattern for Tampa Bay and environs 
can be qualitati\'ely described as follows: In the channels dis- 
secting the bottom topography, the water salinity is at a maxi- 
mum near the mouth of the bay complex (somewhat above 
'normal' marine), with a very slight gradient to lower salinities 
in Hillsboro Bay. The adjacent shoal waters have a similar 
gradient, from near normal marine salinity at the mouth of 
Tampa Bay to lowest salinities (just slightly above that of river 
water) in upper Hillsboro Bay. Since the salinity in the channels 
is everywhere higher than that of the adjacent sand and grass 
flats, there is also a positive gradient from shallow to deep water. 

The relati\'e abundance distributions of the agglutinated and 
the porcelaneous Foraminifera are shown in Figures 6 and 7, 
respectively. The changing contributions of these two groups 
and that of the hyaline calcareous group reflect the salinity 
gradients just discussed. 

These foraminiferal distributions clearly demonstrate a strong 
correlation between salinity and the relative abundances of each 
of the three groups. Highest salinity waters characteristically 
have high percentages of the porcelaneous type associated with 
them. In successively lower salinities, the hyaline calcareous type 
and then the agglutinated type reach their maximum relative 
abundances. 

LAGUNA MADRE 

Laguna Madre is located within the semi-arid climatic zone 
of Thornthwaite ( 1 948 ) , and, hence, has a more or less persis- 
tent, marked moisture deficiency (Fig. 9). There are no major 
rivers flowing into the area, and there is only very slight fresh- 
water inflow from ephemeral streams during local rainfall (Rus- 
nak, 1960). The excess of evaporation over precipitation allows 
the normal marine Gulf waters to enter the shallow basins 
(average depth, about 25/2 ft-) of Laguna Madre and causes 
the water there to be generally hypersaline. Chlorinities in the 
northern basin range from 22 to 45°/ 00 CI and in Baffin Bay 
from 1 to 45°/oo CI; the southern basin, with lower salinities, 
has up to 35°/oo CI (Phleger, 1960b). 

The temperature of the lagoonal water reflects that of the air 
(Phleger, 1960b) ; and because of the positive thermal gradient 



14 



BREVIORA 



No. 420 



-28*00 



»3'45 



27°50 



57°40 




27*30 



Figure 6. Relative abundance distribution of agglutinated Foraminifera 
from Tampa Bay, Florida. (Data from Bandy, 1956; and Walton, 1964.) 



1974 



FORAMINIFERAL DISTRIBUTION 



15 



82*30' 



-27*50' 



• 2*45 



28*00' 




-27*30 



Figure 7. Relative abundance distribution of porcelaneous Foraminifera 
from Tampa Bay, Florida. (Data from Bandy, 1956; and Walton, 1964.) 



16 BREVIORA No. 420 

in this area from north to south (Espenshade, 1960), the relative 
abundance distribution of the foraminiferal groups can be cor- 
related with this parameter. 

The foraminiferal populations are dominated by the porce- 
laneous types in nearly all samples studied (Phleger, 1960b) 
(Fig. 8).' 

In Laguna Madre, the foraminiferal distributions are related 
to both salinity and temperature. Low salinity areas (Baffin 
Bay) are dominated by hyaline calcareous species; high salinity 
areas by porcelaneous species. But within the hypersaline en- 
\'ironments, the relati\'e proportions of the two types are corre- 
lated with temperature — porcelaneous (most abundant in the 
southern basin) directly, hyaline calcareous inversely. 

General Discussion of the Distributions 

I have shown that the relative abundance distributions of the 
three groups of benthonic Foraminifera are closely related to 
salinity distributions, and occasionally to temperature gradients, 
within several shallow-water environments adjacent to the Gulf 
of Mexico. The relationship on a local scale shows a gradient 
of maximum relative abundances for the three groups, from 
agglutinated forms in low salinity waters, to hyaline calcareous 
forms in waters of intermediate salinities, to porcelaneous forms 
in waters of highest salinity. Each of the various t) pes does not 
necessarily dominate the fauna at its maximum, but only reaches 
its peak relative abundance there for the bay or estuary under 
consideration. 

Some modifications to this sequence occur. Most can be ex- 
plained as the simple displacement of either or both of the end- 
member groups — the agglutinated and the porcelaneous types 
— from the sequence. Thus, for example, in the Mobile Bay- 
Mississippi Sound environment, the porcelaneous forms are not 
present, and the sequence ends with the hyaline calcareous maxi- 
mum. However, at the opposite end of the spectrum, the agglu- 
tinated types not only reach their maximum, but completeh 
dominate the upper bay fauna to the exclusion of any calcareous 
forms. This situation is correlated with a much hie^her runoff 
and consequent lower salinity for this estuary than for most of 
the others. 

On the other hand, the samples from Laguna Madre yielded 
almost no agglutinated Foraminifera while the hyaline calcareous 
forms reach their maximum abundance in waters of the lowest 



1974 



FORAMINIFERAL DISTRIBUTION 



17 




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18 BREVIORA No. 420 

salinity and temperature. Thus, the sequence is still preserved, 
but with one end-member excluded. This area is characterized 
by higher than "normal" marine salinities and by high tempera- 
tures. 

Intermediate faunal and environmental situations are present 
and, as might be expected, are located geographically between 
these end-member dominances. Matagorda Bay and environs 
is a good example of these conditions. The foraminiferal fauna 
is everywhere dominated by the hyaline calcareous types, to the 
near exclusion of agglutinated and porcelaneous types. This can 
be correlated with intermediate regional temperatures and with 
the close balance of run-off plus precipitation against evapora- 
tion, the latter of which produces a salinity near the normal 
value for the open Gulf in that region (which is slightly below 
"normal" marine; cf. Fig. 3). 

This sequence in maxima of the relative abundances of the 
three groups of Foraminifera is present not only on a local scale 
within a bay or lagoon, but also on a regional scale, across the 
entire northern Gulf of Mexico. Just as on a local scale, the 
trend is correlated with salinity and with temperature. 

There are two regional trends in the environment (or climate) 
which we must recognize. These are : 1 ) the gradual increase 
in temperature from north to south; and 2) the gradual shift in 
moisture budget from a marked surplus in the Mississippi Delta 
region, westward through a moisture balance near Matagorda 
Bay, to a marked moisture deficit in the region about Laguna 
Madre, and eastward to a near balance, but definite surplus, 
alonsf most of the Florida coast. 

The relati\'e abundance distributions of the three groups of 
benthonic Foraminifera together with isotherms of the January 
normal temperature and with the moisture budget zones (after 
Thornthwaite, 1948) of the coastal region of the northern Gulf 
of Mexico have been summarized in Figure 9. The sequence in 
maxima of relative abundances of the Foraminifera, correlative 
with a sequence of environmental factors, can be seen as a re- 
gional continuum from Mobile Bay, along the Louisiana and 
Texas coasts, to Laguna Madre. The Mobile Bay foraminiferal 
fauna is dominated, for the most part, b) agglutinated species. 
This is correlated with excessive moisture and consequent low 
salinity water within the bay. In addition to this, mean annual 
temperatures are here near the lowest for the Gulf area. 

Sabine Lake, the next area of study to the west, again has a 
fauna dominated by agglutinated species (Kane, 1967) and is 



1974 



lORAMINII FRAL DISTRIBUTION 



19 




>50X PORCELANEOUS FORAMINIFEHA 
JANUARY NORMAL ISOTHERMS 
MOISTURE BUDGET ISOPLETHS 



FLORIDA BAY 



Figure 9. Dominance of agglutinated, hyaline calcareous, and porcelaneous 
Foraminifera in the northern Gulf of Mexico paralic environments; including 
January normal isotherms after Espenshade (1960) , and moisture budget 
isopleths after Thorn thwaite (1948) . 



included, essentially, within the same environmental zones as 
Mobile Bay. The moisture surplus is actually less than in the 
previous area, but this is compensated by the greater restriction 
from mixing with the open Gulf. 

To the southwest, Matagorda Bay and environs is within a 
warmer climatic zone and is also within a zone of only very 
slight moisture surplus. Emphasizing this lower moisture surplus 
is the lack of large rivers discharging fresh water into the bay. 
The result is relatively warm water with salinities near, but some- 
what less than, those of the adjacent Gulf. Commensurate with 
this rise in water temperature and salinity over that of Sabine 
Lake and Mobile Bay is a shift in the foraminiferal fauna. Here 
the hyaline calcareous forms dominate (Lehmann, 1957; Shen- 
ton, 1957). 

San Antonio Bay and environs displays an anomalous, but 
explicable, reverse in the environmental and faunal sequence 
(Parker, Phleger, and Peirson, 1953; Phleger, 1956; Shepard 
and Moore, 1955 and 1960), despite its position within the 
climatic trend to higher temperatures and greater moisture de- 
ficiency. The influx of fresh water to the bays from the relatively 
large San Antonio-Guadalupe River system is the cause of the 
much lower water salinity values here than in Matagorda Bay, 
which is in a general area of greater moisture surplus. There is 
a correlative shift in the foraminiferal fauna to one dominated 



20 BREVIORA No. 420 

in the upper bay by agglutinated forms. The central and lower 
bay fauna is dominated by hyaline calcareous forms as in Mata- 
gorda Bay, but there is still a higher proportion of agglutinated 
types in the former area, commensurate with the lower average 
salinity there. 

Laguna Madre, in a climatic zone of high annual tempera- 
tures and marked moisture deficiency, completes the faunal se- 
quence obsen^ed on a smaller scale in some of the bays around 
the Gulf. Agglutinated Foraminifera are virtually absent from 
all samples taken in the lagoon (Phleger, 1960b). In the north- 
ern basin of the lagoon, the proportion of hyaline calcareous 
specimens is slightly less than that of porcelaneous. And the 
porcelaneous types overwhelmingly dominate the southern basin. 
Hence, there is a direct correlation between temperature and the 
proportion of porcelaneous forms in the bottom sediment. 

An environmental continuum and faunal dominance sequence 
similar to that just described can be documented for the Florida 
Gulf coast and correlated with climatic trends from Mobile Bay 
to Florida Bay. The change in moisture budget is not so dra- 
matic as to the west, as a surplus is maintained along the entire 
coast to the tip of Florida (Fig. 9). However, the temperature 
gradient is even steeper, making Florida Bay approximately 6°C 
warmer than Laguna Madre during January, though both are at 
comparable latitudes. 

The sequence in maxima of relative abundances of the three 
benthonic groups is developed and can be correlated with the 
general environmental trend to higher salinities and higher tem- 
peratures to the south. After Mobile Bay, with its overwhelming 
dominance of agglutinated Foraminifera, the next area to the 
south is Tampa Bay.. The whole foraminiferal sequence is de- 
veloped here, but the hyaline calcareous types dominate the 
fauna over the greater part of the bay, except in the deep chan- 
nels. Charlotte Harbour and vicinity has a similar fauna, largely 
dominated by hyaline calcareous forms (data after Bandy, 
1954), though the whole sequence is again present. Both of 
these areas are similar environmentally and climatically. Both 
are in the wet subhumid zone and both receive limited drainage 
from the surrounding, low-lying, karst topography. There is 
some difference in latitude and hence, in mean annual tempera- 
ture, but this is minimal. Thus, the two areas have very similar 
foraminiferal faunas. 

The fauna of Florida Bay is dominated in the near-shore, 
lower salinity areas by hyahne calcareous types, and by por- 



1974 FORAMINIFERAL DISTRIBUTION 21 

celaneous types seaward, toward the keys (Lynts, 1962). This 
fauna! composition is similar to that of Laguna Madre, but with 
a slightly greater proportion of hyaline calcareous types. Thus, 
despite its location within a wet subhumid climatic zone 
( Fig. 9 ) , comparable in this respect to Matagorda Bay, it has a 
fauna similar to that of a lagoon within a semi-arid zone. Mata- 
gorda Bay and Florida Bay both have only very small rivers 
emptying into them. The differences between Florida Bay and 
Mata2:orda Bav, and the similarities that the former has with 
Laguna Madre can perhaps be explained on the basis of salinity 
of adjacent Gulf water, and on the basis of temperature. 

The salinity of the open Gulf water replacing that evaporated 
from Florida Bay is somewhat higher than that entering Laguna 
Madre, and considerably higher than that available to Mata- 
gorda Bay ( Fig. 2 ) . Mean annual temperature at Florida Bay 
is somewhat higher than at Laguna Madre and considerably 
higher than at Matagorda Bay (Fig. 9). Thus, though the 
water of Florida Bay is diluted by runoff and precipitation simi- 
lar to that for Matagorda Bay, it can be more quickly reconsti- 
tuted to a higher salinity owing to greater evaporation and easier 
mixing with waters more saline than "normal" marine. It is also 
possible that the high proportion of porcelaneous Foraminifera 
should be correlated with the higher temperatures there, as I 
postulated for Laguna. Madre. 

To summarize the distributions and correlations discussed in 
this section, the following conclusions can be drawn. On a local 
scale, i.e., within a bay, lagoon, or other shallow-water environ- 
ment, there is a succession of relative abundance maxima from 
agglutinated, through hyaline calcareous, to porcelaneous types; 
this is correlated with a trend in salinity or temperature values 
from low to high for the area. Also, either or both of the end- 
member types can be displaced from the sequence with commen- 
surate shifts in the salinity and temperature gradients. These 
gradients are the most obvious factors of the environment to 
which the faunal sequence can be related. There are essentially 
uniformly shallow depths over most of the areas, and no ap- 
parent correlation of the faunal groups with bathymetry. Where 
several different sediment types are present within a single bay 
area, they are generally correlated with depth and, hence, not 
correlated with the fauna. In some areas, such as Florida Bay 
and Laguna Madre, a relative abundance sequence in the fora- 
miniferal types is correlated with the temperature or salinity 



22 BREVIORA No. 420 

gradient in each bay despite the uniformity of bottom sediment 

type. 

Regionally, the same foraminiferal sequence is present — man- 
ifested in the various types dominating the population from bay 
to bay in succession. This sequence is again correlated with a 
general trend in salinity and temperature. This trend in the 
shallow-water environmental continuum is explicable in terms of 
climate and physiography of the adjacent coastal plain. The 
main climatic factors necessary for explanation are moisture 
balance and temperature. The influence of physiography on 
the local en\'ironment is evident in the amount of runoff carried 
into the various areas of investigation. 

Environmental Factors Controlling 
Distribution of Foraminifera 

I present the hypothesis that the actual environmental factor 
controlling the distribution of Foraminifera is the availability of 
calcium carbonate (dependent, to a great extent, on salinity, 
temperature, and depth of water) ; or the ease with which these 
one-celled organisms can extract and precipitate CaCOs for 
their test from the surrounding water. 

Chemistry. Revelle (1934), in discussing the physico-chemical 
factors affecting the solubility of calcium carbonate in seawater, 
stated that, from the mass law equation Ca++ X CO3 == 
^CaCOa, three parameters control the solubility of CaCOs: 
concentrations of calcium and carbonate ions and the value of 
the temperature-dependent constant ^CaCOs. "These factors 
are in turn dependent on salinity, temperature, hydrostatic pres- 
sure due to depth below the surface, carbon dioxide content, 
and the concentration of hydrogen and hydroxyl ions, as indi- 
cated by the /?H" (Revelle, 1934: 103-104). Revelle and 
Fairbridge (1957: 256) conclude that the two most important 
processes facilitating the precipitation of calcium carbonate 
probably are : ( 1 ) an increase in temperature, which lowers the 
solubility of CO2, thus increasing the carbonate ion concentra- 
tion; and 2) evaporation, which increases the calcium ion con- 
centration and carbonate alkalinity. 

These two processes, governing the carbonate ion and calcium 
ion concentrations, respecti\ely, can be equated with increasing 
temperature and increasing salinity. Thus, in low salinity and 
low temperature environments calcium carbonate will not be 
easily precipitated, owing to low calcium and low carbonate ion 



1974 FORAMINIFERAL DISTRIBUTION 23 

concentration, the latter being largely a result of increased solu- 
bility of CO2 in the water. On the other hand, waters with high 
salinites and high temperatures, with their relatively high cal- 
cium and carbonate ion concentrations, are saturated or super- 
saturated with respect to calcium carbonate, as in tropical and 
subtropical surface seawater (Chave and Schmalz, 1966). In 
these areas calcium carbonate will be precipitated most readily. 
Thus, all of the environmental parameters tend to increase 
the availability of calcium carbonate from the Mississippi Delta 
region toward the Rio Grande on the west, and toward Florida 
Bay on the east. This trend is closely correlated with the ob- 
sen^d trend in relative abundance distributions of the foramini- 
feral groups studied (see Fig. 9 for a summary of climatic factors 
and the f oraminif eral distributions ) . 

From these observations, it is apparent that agglutinated Fora- 
minifera are relatively most abundant in areas with the lowest 
availability of calcium carbonate. Porcelaneous Foraminifera, 
on the other hand, are associated with high availability of cal- 
cium carbonate, and often dominate the foraminiferal faunas of 
warm, saline tropical or subtropical waters. Finally, the areas 
characterized by intermediate calcium carbonate availability are 
dominated by the hyaline calcareous Foraminifera. This gen- 
eralization is true on nearly all scales of observation: within a 
bay or lagoon, among several adjacent bays of a region, on con- 
tiguous portions of the continental shelf (Greiner, 1970), and 
on a worldwide scale. 

Mechanism. The agglutinated Foraminifera do not require 
the precipitation of calcium carbonate in construction of their 
tests. They utilize the available sediment grains, cementing them 
together with a predominantly organic material (Hedley, 1963; 
Towe, 1967). They are therefore free of restriction to any of 
the marine or estuarine environments. The calcareous Fora- 
minifera (both hyaline calcareous and porcelaneous), on the 
other hand, require calcium carbonate for the construction of 
their tests. The extent to which its availability is required de- 
pends upon the ability of the organism to concentrate and secrete 
( or allow precipitation of ) calcium carbonate against ( or within ) 
the chemical environment of the water. I suggest that a funda- 
mental distinction between the hyaline calcareous and the por- 
celaneous Foraminifera lies herein. 

Electron microscope studies (Hay, Towe, and Wright, 1963; 
Towe and Cifelli, 1967; Lynts and Pfister, 1967) have shown 
that there is a radical difference between the shell structure of 



24 BREVIORA No. 420 

porcelaneous Foraminifera and that of the hyahne calcareous 
types. In the porcelaneous wall there is a thick, inner layer with 
a three-dimensionally "random" array of elongate crystals and 
a pavement-like, surface veneer that in part exhibits preferred 
orientation. The hyaline calcareous wall, on the other hand, is 
made up of calcite crystals with a preferred orientation, the 
whole wall being penetrated by numerous pores, which are visi- 
ble under the light microscope as well (Towe and Cifelli, 1967). 
These observ^ations are consistent with the general separation 
(Loeblich and Tappan, 1964) of the hyaline calcareous and 
the porcelaneous wall t}pes on the basis of perforations of one 
type and porcelaneous appearance of the other. 

Lynts and Pfister (1967) have pointed out the differences in 
crystallization of the wall as obser\'ed for these two test types. 
One species with a hyaline calcareous wall was obser\'ed in the 
process of chamber formation (Angell, 1967a and b). The fora- 
minifer, when beginning to add a new chamber, extended a 
portion of its protoplasm through the aperture of the test, form- 
ing a bulbous drop with the exact shape of the prospecti\T 
chamber. An organic sheath formed on the surface of the drop. 
Shortly thereafter, protoplasm was again exuded (through the 
new aperture in the organic sheath) and covered, in a thin film, 
the surface of the new, tectinous chamber wall. Calcite crystals 
were then observed to nucleate on the organic surface and to 
grow upward (perpendicular to the surface) within the exuded 
cytoplasm, until the calcareous wall was complete. Observations 
by Towe and Cifelli ( 1967) suggest that other hyaline calcareous 
species also nucleate calcite crystals for test formations on an 
organic base."^' 

Arnold ( 1 964 ) , while obserxdng chamber formation of a por- 
celaneous species (similar to that of hyaline calcareous types up 
to the secretion of calcite ) , noted that the calcite crystals grew 
in "random" fashion within the oroanic matrix formed bv the 
exuded cytoplasm of the protist, not upon an organic nucleating 
surface (see Fig. 10 for a diagrammatic comparison of crystal 
growth in the two types). Lynts and Pfister (1967) have pointed 
out this difference between these two test types, and Towe and 
Cifelli (1967), likewise, conclude that porcelaneous wall struc- 
ture is significantly different from hyaline calcareous. 

I suggest that the absence of a nucleating surface for the se- 

*Subseqiient work by Towe (1972) suggests that this may not be true 
for all Foraminifera in this group. 



1974 



FORAMINIFERAL DISTRIBUTION 



25 



SCHEMATIC DEVELOPMENT OF HYALINE 
CALCAREOUS WALL TYPE 



iXUDiO 
PROTOPLASM 



CAICITI CRYSTALS 




ORGANIC 
NUCLEATING 
SURFACE 



EMBRYONIC CRYSTAL 
STAGI 



FINISHED C AlCITE 
WALL 



SCHEMATIC DEVELOPMENT OF PORCELANEOUS 

WALL TYPE 



EMRRrONIC CRYSTALS 




EXUDED 
PROTOPLASM 




INNER 
O 



RGANIC ^ 




EMBRYONIC CRYSTAL 
STAGE 



FINISHED CAICITE 
WALL 



Figure 10. Diagrammatic sketch illustrating differences in test wall 
calcification in porcelaneous and hyaline calcareous Foraminifera. See text 
for discussion. 



26 BREVIORA No. 420 

cretion of calcite by the porcelaneous Foraminifera dictates that 
they Hve within an environment of readily available calcium 
carbonate ^ — ^ at the point of "saturation'' or even "supersatura- 
tion."*^^ The nucleating surface employed by the hyaline cal- 
careous Foraminifera, however, allows them a greater range of 
habitable en\'ironments. Because of this, they can do well both 
in normal marine and in slightly hypersaline conditions, and are 
pre\'ented from thriving only within areas of low calcium car- 
bonate availability (usually low salinity) and areas of "hyper- 
supersaturation" (see below for further discussion). 

In the very low salinity environments, where the availability 
of calcium carbonate is below the threshold required by hyaline 
calcareous forms, the agglutinated Foraminifera will predomi- 
nate. This is so simply because the agglutinated species are not 
restricted by such a boundary, while the calcareous types are. 
As waters with more readily available calcium carbonate are 
approached, more hyaline calcareous forms will be present, 
thus diminishing the relative abundance of agglutinated types. 
Though the agglutinated types are not excluded from en\iron- 
ments of high calcium carbonate availability, they are subordi- 
nate in abundance to the calcareous forms there. This can be 
explained by the ability of calcareous forms to di\ersify and 
occupy ecological niches not as readily a\'ailable to the aggluti- 
nated types {e.g., marine plants), as the construction of an ag- 
glutinated test ties the protist to its source of raw material — 
the bottom sediments. (Again, this is a relative situation. I am 
aware that some agglutinated types may live on marine plants 
utilizing the fine sediment dust that clings to their surfaces for 
test construction.) 

The porcelaneous types reach their maximum relati\e abim- 
dance under en\'ironmental conditions of maximum a\'ailability 
of calcium carbonate — the tropics and subtropics with high 
temperatures and hypersalinities. Their proportion of the total 
fauna decreases in the direction of lower calcium carbonate 
availability, toward lower temperatures as in Laguna Madre, or 
toward lower salinities as in Florida Bay. This is so because they 
have greater difficulty in secreting calcite in these environments, 

**I use the terms "saturation," "supersaturation," and "hyper-super- 
saturation" in a relative sense. Though these terms do have definite 
meanings in chemistry, it is difficult to say at what point a sea-water 
solution is "saturated" with respect to CaCO.j in a natural environment, 
and even more difficult to state tlie relation of the foraminiferids to some 
precise value of saturation. They can be related relatively, however. 



1974 FORAMINIFERAL DISTRIBUTION 27 

while the hyaline calcareous types are seemingly not hindered in 
this process until very low salinities or temperatures are reached. 
The porcelaneous types can completely dominate the fauna in 
en\ironments of \^ery high calcium carbonate availability owing, 
perhaps, to the unordered crystalline nature of their test walls. 
Hyaline calcareous types would perhaps be unable to secrete 
well-ordered crystals in an environment of calcium carbonate 
"hyper-supersaturation." 

Consequently, Foraminifera with hyahne calcareous walls 
reach their maximum relative abundance in areas of intermedi- 
ate calcium carbonate availability, where the porcelaneous types 
are greatly diminished owing to problems of calcite secretion. 

Summary. An hypothesis has been proposed to explain the 
obser\'ed foraminiferal sequence correlated with salinity and 
temperature gradients within estuarine environments. The en- 
vironmental factor thought to control the distributions of major 
groups is the availability of calcium carbonate utilized in test 
construction by two of the types. This factor is dependent mainly 
on temperature, salinity, and CO2 content of the water. 

This hypothesis adequately explains the observed distributions 
of these groups; it explains, through physiologic interaction with 
the en\'ironment, the correlation between foraminiferal groups 
and temperature and salinity gradients; and it ultimately ex- 
plains the correlation of these groups with climatic factors. The 
fact that this correlation exists between the foraminiferal se- 
quence and the environmental factors reducible to calcium car- 
bonate availability, and the fact that this relationship can be 
explained by varying abiHties of the foraminifers to construct 
tests suggest, that these organisms secrete calcite in near-equi- 
librium with their environment. This implies, further, that these 
protists are unable to concentrate and precipitate calcium car- 
bonate from the seawater in \'ery great chemical opposition to 
their surroundings and that they are, in this sense at least, 
simple organisms, dependent on, and controlled to a great extent 
by, their environment. 

Geologic Significance of Results 

The understanding of environmental effects on the distribution 
of organisms and on the modification of phenotypes is essential 
to the interpretation of paleoenvironments. The purpose of this 
study has been to gain some understanding of factors governing 
the distribution of Foraminifera in Recent environments. The 



28 BREVIORA No. 420 

difficulty in learning the causes of distribution of any particular 
species is apparent, and geologic applicability of such knowledge 
is severely limited by the geologic range of the species. In this 
light, I have sought to determine the environmental control on a 
characteristic of the fauna that transcends the specific level of 
classification and w^hich is amenable to paleoecologic extrapola- 
tion. I have shown that Foraminifera are distributed within the 
Recent environment in a fashion covariant with certain factors 
summarized as the availability of CaCOs. The proposition that 
the availability of CaCOs is indeed the cause of their relative 
abundance distribution is supported by a credible explanation, 
on the physiologic level, of foraminiferal test construction. 

The understanding of distributions at this level depends only 
on a knowledge of the wall types, not on individual character- 
istics of a taxonomic group. Much can be learned concerning 
salinity and temperature distributions in ancient seas and estu- 
aries through use of Foraminifera at this morphologic le\'el. 
With a more thorough understanding of the causes of plank- 
tonic distributions and changes in foraminiferal diversity on the 
continental shelf, more can be learned of paleobathymetry and 
location of shore-lines. 

Since work with the Foraminifera at this level circum\'ents the 
problems associated with extending interpretations of \'arious 
Recent taxa back in time, application of the principles gained 
can be extrapolated through the Mesozoic to the beginnings of 
the calcareous Foraminifera. One major assumption must be 
made for the interpretation of fossil faunas. This is that the 
ability of Foraminifera to secrete calcite for particular wall types 
within a given environment of CaCOs availability has not 
changed appreciably since the corresponding development of 
each test type. This assumption, it would seem, is a fair one; if 
the crystalline structure within the wall of Jurassic porcellaneous 
Foraminifera is similar to that found in Recent specimens of 
that wall type, it is reasonable to assume that the physiologic 
processes that produced it were similar. 

Perhaps a more important inference can be drawn from the 
results of this study. If the Foraminifera depend to such an 
extent on the availability of CaCOs in specific degrees of satura- 
tion or supersaturation within the environment for secretion of 
their tests, then they cannot readily concentrate these ions physio- 
logically and hence cannot easily act in chemical opposition to 
their surroundings. This implies further that other aspects of 
foraminiferal tests are subject to simple control by the en\iron- 



1974 FORAMINIFERAL DISTRIBUTION 29 

ment. I suggest that such factors as general test morphology, 
apertural position and number, and chamber number may be 
go\erned not strictly genetically (as is implied by the erection of 
specific or generic groups based on these characters), but by 
the macro- or microenvironment of the living individual. This, 
then, is an open avenue for research. If environmental causes 
for \arious morphological characteristics can be derived, im- 
measurable, paleoecologic value can be attributed to Foramini- 
fera. 

References 

Angell, R. D. 1967a. The test structure and composition of the fora- 

minifer Rosalina Floridana. J. Protozool., 14: 299-307. 
. 1967b. The process of chamber formation in the fora- 

minifer Rosalina Floridana (Cushman) . J. Protozool., 14: 566-574. 
Arnold, Z. M. 1964. Biological observations on the foraminifer Spirolo- 

culina hyalina Schulze. Univ. Calif. Pub. Zool., 72: 1-78. 
Bandy, O. L. 1954. Distribution of some shallow-water foraminifera in the 

Gulf of Mexico. U.S. Geol. Surv. Prof. Pap. 254-F. 
. 1956. Ecology of Foraminifera in the northeast Gulf of 

Mexico. U. S. G. 5. Prof. Paper 274-G. 
, 1964. General correlation of foraminiferal structure with 



environment. In Imbrie, J., and N. D. Newell (eds.) , Approaches to 
Paleoecology. John Wiley, pp. 75-90. 
AND Arnal, R. E. 1960. Concepts of foraminiferal paleoecology. 



Amer. Assoc. Petrol. Geol., Bull. 44: 1921-1932. 
Chave. K. E. and Schmalz, R. F. 1966. Carbonate-seawater interactions. 

Geochim. et Cosmochim. Acta, 30: 1037-1048. 
ESPENSHADE, E. B., Jr., cd. 1960. Goode's World Atlas: Rand-McNally. 
FuNNELL, B. M. 1967. Foraminifera and Radiolaria as depth indicators 

in the marine environment. Marine Geol., Special Issue, 5/6: 33-47. 
GooDELL, H. G. AND GoRSLiNE, D. S. 1960. A sedimentologic study of 

Tampa Bay, Florida. Internat'l Geol. Cong., 21st Session, Norden, pt. 

XXIII. 
Gre'iner, G. O. G. 1969. Environmental factors causing distributions of 

Recent Foraminifera. Ph.D. Thesis, Case Western Reserve University, 

195 pp. 
. 1970. The distribution of Recent benthonic foramini- 
feral groups on the Gulf of Mexico continental shelf. Micropaleontology, 

16(1): 83-101. 
Hay, W. H., Towe, K. M., and Wright, R. C. 1963. Ultra-microstructure 

of some selected foraminiferal tests. Micropaleontology, 9: 171-195. 
Hedley, R. H. 1963. Cement and iron in the arenaceous Foraminifera. 

Micropaleontology, 9: 433-441. 



30 BREVIORA No. 420 

Kane, H. E. 1966. Sediments of Sabine Lake, the Gulf of Mexico, and 
adjacent water bodies, Texas-Louisiana. Jour. Sed. Petr., 36: 608-619. 

. 1967. Recent microfaunal biofacies in Sabine Lake and en- 
virons, Texas-Louisiana. Jour. Paleont. 41: 947-964. 

Lehmann, E. p. 1957. Statistical study of Texas Gulf coast Recent fora- 
miniferal facies. Micropaleontology, 3: 325-356. 

LiDZ, L. 1965. Sedimentary environments and foraminiferal parameters: 
Nantucket Bay, Massachusetts. Limn, and Oceanog., 10: 392-402. 

LoEBLicH, A. R. AND Tappan, H. 1964. Sarcodina, chieflv "Thecamoebians" 
and Foraminifera. In Treatise on Invertebrate Paleontology, Part C, 
Protists 2, V. 1 and 2, R. C. Moore, ed. Lawrence, Kansas: LTniv. 
Kansas and Geol. Soc. America, pp. C55-C164. 

Lynts, G. W. 1962. Distribution of Recent Formaminifera in Upper 
Florida Bay and associated sounds. Contrib. Gush. Found. Foram. 
Res. XIII, pp. 127-144. 

AND Pfister. R. M. 1967. Surface ultrastructure of some 

tests of Recent Foraminifera from the Dry Tortugas, Florida. J. Pro- 
tozool., 14: 387-399. 

Parker, F. L. 1948. Foraminifera of the continental shelf from the Gulf 
of Maine to Maryland. Bull. Mus. Comp. Zool., 100: 213-41. 

, Phleger, F. B., and Peirson, J. F. 1953. Ecology of Fora- 
minifera from San Antonio Bay and environs, southwest Texas. Gush. 
Found. Foram. Res., Special Pub. 2. 

Phleger, F. B. 1954. Ecology of Foraminifera and associated organisms 
from Mississippi Sound and environs: Amer. Assoc. Petrol. Geol., Bull. 
38: 584-647. 

. 1956. Significance of living foraminiferal populations along 

the central Texas Goast. Gontrib. Gush. Found. Foram. Res. \\\. pp. 
106-151. 

. 1960a. Ecology and Distribution of Recent Foraminifera. 



Baltimore: Johns Hopkins Press. 

1960b. Foraminiferal populations in Laguna Madrc. Texas. 



Sci. Repts. Tohoku Univ., 2nd Ser. (Geol.), Special \'ol. 4: 83-91. 
. 1964. Foraminiferal ecology and marine geology: Marine 



Geol., 1:16-43. 
and Parker. F. L. 1951. Ecology of Foraminifera. Xoitli- 



west Gulf of Mexico. Geol. Soc. .Aimerica, Memoir 46. 
Revelle. R. 1934. Physico-chemical factors affecting the soluhiliiv of 

calcium carbonate in sea water. Jour. Sed. Petr.. 4: 1031 10. 
AND FAiRBRmGE, R. 1957. Carbonates and carbon dioxide. In 

Treatise on Marine Ecology and Palcoecology, Vol. 1. Ecology. J. ^V. 

Hedgpeth, ed. New York Gity: Geol. Soc. America, Memoir 67. 
RusNAK. G. A. 1960. Sediments of Laguna Madre, Texas. /;/ Recent 

Sediments, Northwest Gulf of Mexico, F. P. Shepard et al., eds. Tulsa: 

.\mer. Assoc. Petrol. Geol. Pub. 
Shenton, E. H. 1957. A studv of the Foraminifera and sediments of 



1974 FORAMINIFERAL DISTRIBUTION 31 

Matagorda Bay, Texas. Trans. Gulf Coast Assoc. Geol. Soc, v. VII, 
pp. 135-150. 

Shepard, F. p. and Moore, D. G. 1955. Central Texas coast sedimenta- 
tion: characteristics of sedimentary environment, Recent history, and 
diagenesis. Amer. Assoc. Petrol. Geol., Bull., 39: 1463-1593. 

. AND . 1960. Bays of central Texas coast. In 

Recent Sediments, Northwest Gulf of Mexico, F. P. Shepard, et al., eds. 
Tidsa: Amer. Assoc. Petrol. Geol. Pub. 

Stehli, F. G. 1966. Some applications of foraminiferal ecology. Proc. 
2nd W. African Micropaleo. Coll. (Ibadan, 1965) , pp. 223-240. 

AND Creath, W. B. 1964. Foraminiferal ratios and regional 

environments. Amer. Assoc. Petrol. Geol., Bull. 48: 1810-1827. 

Thornburv, W. D. 1965. Regional Geomorphology of the United States. 

New York: John Wiley and Sons. 
Thornthwaite, C. W. 1948. An approach toward a rational classification 

of climate. Geog. Rev., 38: 55-94. 
Towe, K. M. 1967. Wall structure and cementation in Haplophragmoides 

canariensis. Contrib. Gush. Found. Foram. Res. XVIII, pp. 147-152. 
. 1972. Invertebrate shell structure and the organic matrix 

concept: Biomineralization, 4: 1-13. 

and Cifelli, R. 1967. Wall ultrastructure in the calcareous 



Foraminifera: crystallographic aspects and a model for calcification. 

Jour. Paleo., 41: 742-762. 
Up-shaw, C. F. and Stehli, F. G. 1962. Quantitative biofacies mapping. 

Amer. Assoc. Petrol. Geol., Bull. 46: 694-699. 
, Creath, W. B., and Brooks, F. L. 1966. Sediments and 

microfauna off the coasts of Mississippi and adjacent states. Miss. Geol., 

Econ.. and Topo. Surv., Bull. 106. 
Walton, W. R. 1964. Ecology of benthonic Foraminifera in the Tampa- 

Sarasota Bay area, Florida. In Papers in Marine Geology, Shepard 

Commemorative Vol., R. L. Miller, ed. New York: MacMillan. 
Wantland, K. E. 1967. Recent benthonic Foraminifera of the British 

Honduras shelf. Ph.D. Thesis, Rice Univ. 

Appendix 

On the Construction of Calcite Walls 
IN Foraminifera 

The Ihing calcareous Foraminifera have been divided into 
two suborders on the basis of general test wall construction : the 
Miliolina have nonporous, porcelaneous walls ; the Rotaliina ha\'e 
a glassy appearance, and are penetrated by numerous pores. 
Studies with the electron microscope have upheld this basic 
distinction and have revealed the crystal arrangements underly- 
ing and producing this difTerence, as seen by the light micro- 
scope. 



32 . BREVIORA No. 420 

The miliolid test wall is composed of two layers of calcite 
rhombs or needles: an inner, "randomly" oriented layer (which 
is the thicker) and an outer, pavement-like layer, one rhomb 
thick, with the rhombs oriented parallel to the surface. The 
crystallization process in miliolid foraminifers has been observed 
and reported by Arnold and by Lynts. The process is as follows : 
Cytoplasm is extruded through the aperture ; it then takes on the 
form of the new chamber. A layer of fibrous organic matter is 
deposited on the surface of the chamber and will become the 
"inner organic lining" of the test. After the new aperture is 
formed, cytoplasm is again extruded, but this time it covers the 
new chamber in a thin organic sheath, which is to act as ihe 
crystallizing matrix. 

Mineralization then occurs in two waves of crystal growth, 
with the rhombs being nucleated either spontaneously or by 
properly patterned organic molecules, but at many "randomly" 
placed sites throughout the sheath of matrix. This results in 
growth of the crystals in a nonoriented fashion within an im- 
miscible solvent. This will be contrasted with the result of 
oriented crystal s^rowth in the rotaliids. 

Thus the randomly oriented rhombs in the inner layer are 
the result of randomly oriented crystal nuclei. What special 
mechanism operates to orient the surface rhombs? I believe this 
is simply the result of surface tension at the protoplasm-seawater 
interface, acting on the elongated crystals to align them parallel 
to that surface. No biological directives are required; it is a 
simple, physical process. No special crystallizing mechanisms 
should be sought, and no adapti\'e significance can be attached 
to this pa\^ement-like surface layer. 

The mineralization process in a hyaline calcareous foraminifer 
has been watched and reported by Angell, and a mechanism 
for this process has been proposed by Towe and Cifelli on the 
basis of the electron microscopic study of test wall sections. The 
process is as follows: Cytoplasm is extruded through the aper- 
ture, and takes on the shape of the chamber to be formed. A 
fibrous ors^anic laver is secreted to cover the chamber. The cvto- 
plasm is again extruded through the new aperture and covers 
the new chamber in a thin organic sheath. To this point the 
process is similar to that of the miliolids, but the fibrous organic 
layer, which was merely an inner lining for the miliolid, has 
taken on a new function. It apparently acts as a template for 
calcite nucleation. CrystalHzation then takes place beginning on 
this template, with the calcite crystals growing upward within 



1974 FORAMINIFERAL DISTRIBUTION 33 

the organic sheath. When the process is completed, there are 
crystals and pores oriented perpendicular to the test surface. 

It is my opinion that these pores and crystals are simply the 
result of oriented crystallization of two immiscible substances 
from an originally miscible solution — the cytoplasmic sheath. 
My analysis of the process is as follows: The entire fibrous sur- 
face of the new chamber can act as a nucleation template. How- 
ever, as crystallization commences, both calcite and organic mat- 
ter are coming out of solution. Since these are immiscible as 
solids, there will be separation of the two phases. Organic mat- 
ter will be excluded from the calcite crystal lattice and will 
migrate toward, and collect in, relatively equally spaced organic 
plugs on the template surface (the "pore processes" of Angell). 
As crystallization continues, the same process will result in the 
upward growth of the two separated phases: calcite will con- 
tinue to crystallize on calcite, and organic matter on the pore 
processes. The final result is a wall with oriented calcite crystals, 
penetrated by organic plugs, which upon death and decay will 
leave the characteristic "pores" of the hyaline calcareous fora- 
minifers. 

The results of the same process can be observed on a macro- 
scopic level, and in an even more convincing manner, in your 
home refrigerator. Most ice cubes exhibit "pore" structures 
amazingly similar to those of the hyaline calcareous Foramini- 
fera. They are formed by the entrapment of gases formerly 
dissolved in the water, which must come out of solution during 
crystallization. If freezing proceeds from the top down, the gas 
cannot escape into the atmosphere, and space within the cube 
must be provided. As crystallization proceeds the water becomes 
saturated with the gas, and as it comes out of solution, it tends 
to gather into bubbles at more or less equally spaced sites at the 
ice surface. This, I am suggesting, is analogous to the separation 
and collection of organic matter into the "pores" of foraminiferal 
walls during their mineralization. 

The total volume of pore space in the ice cube is dependent 
on the amount of dissolved gas at the onset of crystalHzation, but 
the pore size and density is related to rates of crystallization, as 
indicated by a few simple experiments which I conducted. The 
faster the cooHng rate of the ice, the smaller, and hence more 
closely spaced are the pores. This is reasonable, as greater mi- 
gration of the excluded molecules is possible with slower cooling. 

The extension of the original bubbles, and hence the elonga- 
tion of the pores, is the result of simple physical processes. As 



34 BREVIORA No. 420 

crystallization continues ice will tend to extend alreadv-existinor 
ice crystals, and the gas will collect at sites already occupied b\ 
gas. When the entire solution is used up, crystallization stops 
and the analogy is complete. 

Thus "pores" are de\'eloped in the crystallization of ice with- 
out the ,need of biologically derixed genetic directives, and, I 
suggest, the same mechanism operates in the calcification of 
foraminiferal walls. Surely no "adapti\^e significance" can be 
ascribed to ice cube pores. Likewise, I believe we err in search- 
ing for a "purpose" in the construction of foraminiferal pores. 
I think the pores are simply the result of the simultaneous crystal- 
lization of two immiscible substances upon a nucleation template. 
Pores do not develop in the porcelaneous walls because nucle- 
ation of the calcite crystals is at many sites, scattered throughout 
the matrix, and exclusion of organic matter from the lattice dur- 
ing crystal growth is accomplished by merely pushing it aside; 
whereas, in the rotaliid wall, calcite is being nucleated over an 
entire surface, necessarily forcing the organic matrix to gather 
at particular sites. Thus, it was the mode of calcification, the 
organic nucleating surface, which was selected for, and which 
has adaptive significance, not the "pores." However, this does 
not exclude the possibility that foraminifers use these "pores" in 
the quest for specialized adaptations. By increasing the ratio of 
organic matter to CaCOs (quite possibly through genetic con- 
trol), it is possible to reduce the calcite wall to a mere lattice 
work composed almost entirely of pore space, as in the genus 
Globigerinoides, thereby lightening the test in preparation for a 
planktonic habit. Thus, the very enlarged pores of Globigeri- 
noides are in a close-packed condition resulting in hexagonal 
openings and consequent inter\'ening small triangular calcite 
pedestals serving as bases for the growth of the spines character- 
istic of this genus. The spine growth can be simply ascribed to 
the continued crystallization of calcite in the direction it was 
started — a common phenomenon in crystal growth. 

The factors of pore density and total porosity in recent plank- 
tonic Foraminifera have been studied bv Be and are found to be 
related to environment in a gross way. I suggest that total poros- 
ity will be related to some factor or factors that govern the 
matrix to calcite ratio (perhaps this is entirely genetic) and that 
pore size and density will be found to be related to factors 
go\erning rates of crystallization. And this might more closely 
correlate with en\ironmental parameters. Perhaps in areas of 
CaCO?, supersaturation crystallization will be most rapid, result- 



1974 FORAMINIFERAL DISTRIBUTION 35 

ing in many, minute pores spread over the test, as opposed to 
larger, more widely spaced pores that might be found in regions 
of en\'ironnientally controlled slow rates of crystallization. 

In summary, I would like to emphasize that this is purely a 
hypothesis for pore formation based on other hypotheses for cal- 
cification mechanisms in Foraminifera, and quite possibly the 
whole matter is more complex than what I have presented here. 
However, I believe it is important to refresh our thinking by 
coming to problems from new angles, by making analogies in the 
biological world with things or processes in the purely physical 
or chemical world. I especially think that Foraminifera are much 
less complicated biologically than most workers currently sup- 
pose. Much of their activity, their feeding, their shell construc- 
tion can be duplicated in completely nonbiological systems. 
Much of their shell morphology is predictable from a purely 
geometrical point of view; for example, consider the stacking of 
different sized spheres. Thus, in my opinion, Foraminifera, per- 
haps more than any other group of organisms, can be utilized in 
paleoecological studies, because they are basically simple physico- 
chemical systems; they do not exert much biological pressure 
against the environment, and hence they are closely governed by 
the environment; that is, they must work within the confines of 
molecular forces such as surface tension and crystal growth 
processes. 

Foraminifera must be examined in this new light if we are to 
advance in our understanding of them. Foraminifera are not 
molluscs; they do not have their sophisticated biological systems; 
we must stop looking at them as if they do. 



^-'' 



B R E V l.a.K A 



LIBRARY 



Miiseiiiii of Coiiiparative Zoology 



us ISSN 0006-96' 



Cambridge, Mass. 29 March ^^^^ygi^j^j^^^^^^ "^^^ 



A CASE HISTORY IN RETROGRADE EVOLUTION: 

THE ONCA LINEAGE IN ANOLINE LIZARDS. 

I. ANOLIS ANNECTENS NEW SPECIES, 

INTERMEDIATE BETWEEN THE GENERA 

ANOLIS AND TROPIDODACTYLUS. 

Ernest E. Williams 

Abstract. A new anole species bridges the gap between the genus Anolis, 
diagnosed by the presence of adhesive subdigital pads under phalanges ii 
and iii, and Tropidodactylus, diagnosed by the absence of such pads: Anolis 
annectens has typical anoline transverse lamellae with microscopic hairs 
and free distal margins only under phalanx ii; the third phalanx has only 
keeled infradigital scales as in the species onca currently referred to the 
monotypic genus Tropidodactylus. The genus Tropidodactylus is formally 
synonymized with Anolis. A morphological series in the reduction of the 
anoline adhesive pad that culminates in the condition seen in the species 
A. onca is described. 

The genus Tropidodactylus was erected in 1885 by Boulenger 
in the second volume of his classic Catalogue of the Lizards in 
the British Museum (Natural History) to receive the single 
species described as Norops onca by O'Shaughnessy in 1875. 

Neither the genus nor the species has received much atten- 
tion since their description. They have, up to the present, been 
very poorly known. The validity of the genus has not been ques- 
tioned, since the difference between Tropidodactylus and Anolis 
in the defining character of digital structure has seemed a sharp 
and important one: all Anolis (including all those species classi- 
cally referred to Norops) have under phalanges ii and iii ex- 
panded adhesive digital pads, the smooth, flattened, transverse 
lamellae of which are provided with microscopic hairs (Ruibal 
and Ernst, 1965; Killer, 1968; Maderson, 1970; Lillywhite and 
Maderson, 1 968 ) . The adhesive pad may be narrower or wider, 
may be sharply set off ("raised") from phalanx i or not so set 



BREVIORA 



No. 421 



JBC 



Figure 1. Left: toe of an anole showing the "Norops" condition; Right: 
toe showing the typical AnoUs condition. 



off ( the Norops condition ) ( Fig. 1 ) and may ha\'e more or 
fewer lamellae, but there is always some expansion, always 
smooth trans\erse flattened lamellae under phalanges ii and iii, 
and always microscopic hairs. Tropidodactylus, as known from 
the single species onca, has been belie\ed to differ in the com- 
plete absence of the hairs and of smooth lamellae and in the 
presence of multiple keels on the infradigital scales. Although 
in general habitus, including the presence of a large and typically 
anoline dewlap, the species onca has unmistakably the appear- 
ance of Anolis and is often so identified in collections; the digital 
difference has always been regarded as quite worthy of generic 
distinction. It seemed to support this position that, according to 
Ruthven (1922), Tropidodactylus seemed more terrestrial than 
any Anolis: "All of the specimens taken (17) were on the 
ground. It is very shy and at the slightest cause for alarm dashes 
into a hole." 

However, Etheridge (1960) was unable to find any osteologi- 
cal character on which to separate onca generically and re- 
garded this species as the terminal, most specialized member of 
his beta section of the genus Anolis. He was willing to retain 
the genus only on the basis of "the e\'olutionary significance of 
the loss of typical anole subdigital lamellae and the accompany- 
ing alteration in mode of life." 

George Gorman (1969), describing the karyotype of onca, 



1974 ANOLIS ANNECTENS 3 

found it to resemble closely two of the more primitive (or "typi- 
cal") members of the beta group within Anolis [A. lineatopus 
and A. opalinus). The onca karyotype (2n=30) with seven 
macrobi\alents and eight microbivalents is characteristic of this 
group within Anolis, and onca even resembles A. opalinus in 
clear heteromorphism in chromosome pair seven. The only ob- 
vious difference found by Gorman was that pair seven appeared 
relati\ely smaller in onca than in the two compared Jamaican 
anoles, "i.e. it might be considered an intermediate between 
macrochromosomes and microchromosomes." 

New collections of onca have been made by James Collins on 
Margarita Island (reported by him in 1971), by Carlos Rivero- 
Blanco and Abdem R. Lancini on the mainland of Venezuela 
in and near Coro, by Bryan Patterson and the members of his 
paleontological expedition in the same region, by the author, 
A. S. Rand and A. R. Kiester on the neighboring Paraguana 
Peninsula, and by the author, Jane Peterson, K. Miyata and 
R. Salvato on the Paraguana isthmus and on the east side of the 
Goajira Peninsula. 

However, very surprisingly, as a summary of our knowledge 
of the species onca was being prepared, a unique specimen in 
the collection of the Field Museum of Natural History demon- 
strated the existence of a new species that is an ideal intermedi- 
ate between the genera Tropidodactylus and Anolis as currently 
conceived. Differing trivially from onca in color and in some- 
what greater size of the dorsal scales, it differs sharply in having 
smooth lamellae under phalanx ii of the fourth toe, but keeled 
scales under phalanx iii. It thus becomes impossible to make a 
separation of two genera in the fashion that has hitherto been 
customary. It is necessary either to describe a new monotypic 
genus for the new species or to submerge Tropidodactylus in the 
svnonvmv of Anolis. I choose the latter course and describe the 
new species as : 

Anolis annectens new species 

Holotype: FMNH 5679, adult male. 

Type locality: Lago de Maracaibo, collected by W. H. Os- 
good between late January and early March, 1911. 

Head (Fig. 2) : Head stout, a little longer than tibia. Head 
scales unicarinate, 10 scales across snout between second canthals. 
A shallow frontal depression. Nasal scale separated from rostral 
by two intervening scales. 

Supraorbital semicircles separated by one row. Supraocular 



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No. 421 




Figure 2. Head of A. aJinectens Holotype, dorsal view. 



disk ill-defined, consisting of about 12 keeled scales, the largest 
anteromedial, the disk separated by two rows of granules from 
the scales of the supraciliary rows. Two parallel elongate supra- 
ciliaries continued posteriorly by a double series of moderately 
enlarged scales. Canthus distinct, canthal scales 5, second canthal 
scale largest. Loreal rows 6, the lowest row not much larger than 
those above it. Interparietal almost equals ear, separated from 
the supraorbital semicircles by 2 scales. Temporal and supra- 
orbital scales keeled, smallest in center of temporal region, dor- 
sally grading into larger scales surrounding interparietals. Scales 
behind interparietal somewhat smaller than those lateral and 
anterior to it. 

Suboculars separated from supralabials by one row of scales, 
anteriorly not continued to canthal ridge, posteriorly ending 
abruptly with one enlarged scale. Ten supralabials to center 
of eye. 



1974 ANOLIS ANNECTENS 5 

Mental wider than long, in contact posteriorly with 7 unicari- 
nate scales between infralabials. No differentiated sublabials, 
but scales in center of throat smallest. 

Trunk: Middorsal scales enlarged, hexagonal, keeled, grading 
laterally into much smaller but keeled flank scales. Ventrals 
much larger than dorsals, unicarinate, the keels in line. Post- 
anal scales not differentiated. 

Dewlap: Large, scales smaller than ventrals, keeled, arranged 
in widely spaced rows except at the edge. 

Limbs and digits: Hand and foot scales mul tic annate. No 
scales on limbs as large as ventrals, unicarinate. Eight rather 
narrow lamellae under phalanx ii of fourth toe, scales under 
phalanx Hi of fourth toe multicarinate. 

Tail: Tail round, all scales keeled, only ventral scales larger 
than dorsals, 4 scales above, 3 below. 
Size: 67 mm, snout-vent length. 

Color (in alcohol) : Grey-brown with vague blotching and 
mottling on flanks, limbs and tail more distinctly barred. A 
round dark spot above each shoulder and a smaller spot between 
these on the neck middorsally. Narrow oblique transverse bands 
connect the shoulder spots across the middle of the back. A 
transverse band directly in front of shoulder, indistinct on the 
right side. On posterior midline two black spots, one in front of 
sacrum, and one between two lateral sacral spots. Dewlap scales 
are white, with black pigment around the bases of some of them. 
Comparison with onca. Scales: The variation in squamation 
seen in onca O'Shaughnessy completely includes that of the 
single specimen of annectens except in two regards: the greater 
size of the dorsal scales in annectens (Fig. 3) and the presence 
under phalanx ii of smooth lamellae (Fig. 4). 

Color: The color of annectens may also differ from that of 
onca but the variability of onca is so great that the rudimentary 
pattern seen in the type of A. annectens seems easily derivable 
from an onca pattern. Nevertheless there is no exact or nearly 
exact match in any of the extensive series of onca. The shoulder 
spots of onca are roughly triangular or elongate, not round, as in 
annectens. The neck spot and the two posterior midline spots 
of annectens are not exactly matched in onca. The peculiar 
distribution of dark pigment on the dewlap skin in annectens is 
again without real parallel in onca. 

Color in life of annectens is unknown. However, it may be 
presumed from its similarity to onca that at least in body pattern 
the preserved animal gi\^es a very fair impression of the live ani- 



BREVIORA 



No. 421 





Figure 3. Dorsal scales. Above: A. onca. Below: A. annectens Hole- 
type. 



mal. Dewlap color, however, cannot safely be inferred from 
specimens long preserved and this might be important. 

A good description of color in life by William E. Duellman of 
onca from 3 km SW of Cumana in Sucre, Venezuela, follows: 
"Dorsum light brown mottled with gray, gray brown and black. 
Venter creamy white, lightly flecked with grayish brown. Tail 
medium brown above, cream below. Dorsolateral motthng on 
WED 28685 forms more or less distinct paravertebral blotches 
which are gray centrally and outlined in black. Dewlap bright 
greenish ochre centrally, becoming orange peripherally, the whole 
dewlap reticulated with bright orange brown and bearing white 
scales. Iris bronze. Lining of throat bluish gray." [WED field 
notes.] 

Distribution: The locality for A. annectens is, most unfortu- 
nately, inexact. It is not known whether Osgood collected the 



1974 



ANOLIS ANNECTENS 



) ' 









\l\l 



li 



Figure 4. Fourth toe lamellae. Left: A. onca. Right: A. annectens Holo- 
type. In the center the 4th toe of Anolis ("Norops") auratus is shown in 
ventral and lateral view for comparison. 



8 BREVIORA No. 421 

specimen himself or had it brought to him, but the very inex- 
actitude of the data and the absence of any further field notes 
for the specimen (H. Marx, personal communication) indicate 
most probably that Osgood did not have personal knowledge of 
the collecting site. One additional specimen — an Anolis auratus 
(formerly Nor ops auratus) — in the Field Museum received 
from Osgood has the same inexact data. A. auratus is an animal 
occurring in open grassy lowlands and, less abundantly, in bar- 
ren thorn scrub with much cactus. It is a natural first hypothe- 
sis that A. annectens has a similar ecology. 

Osgood (1912) reports the itinerary of his 1911 expedition to 
western Venezuela and eastern Colombia rather fully. Only 
two of his stations are plausible for A. annectens in terms of the 
expectation of a lowland grassy or arid habitat: El Panorama 
8 miles due east of Maracaibo and the Empalado Savannas 30 
miles further east. It is more probable, howe\'er, that both A. 
annectens and A. auratus were among "the few specimens from 
other places . . . obtained from natives in Maracaibo." How- 
ever, an effort to discover annectens by collecting in a variety 
of habitats on both sides of the Lago de Maracaibo in November 
1972 and iVugust 1973 was unsuccessful. For the present no 
better localization of this extraordinary annectant species is pos- 
sible. 

The distribution of A. onca is much better known, though 
some of the literature records are clearly errors of identifica- 
tion or of locality. The British A^Iuseum types described by 
O'Shaughnessy were cited as from "\^enezuela'' and "Domin- 
ica." The latter locality is certainly erroneous (Barbour, 1914^). 
Specimens reported by Marcuzzi (1954) and Aleman (1952, 
1953) from interior Venezuela are misidentifications. I record 
below only the localities that I ha\'e personally \erified by ex- 
amination of specimens (see Fig. 5) : 

COLOMBIA. Guajira. Cabo de la Vela: FMNH 165159. 
Two hours E El Cabo, near Cabo de la Vela: MCZ 85441. 
El Cardon, S Cabo de la Vela: RNHL 7707. Maicao: USNM 
115067. Manaure and Pajaro areas: USNM 151517-23. Media 
Luna, E Cabo de la Vela toward Bahia de la Protete: MCZ 
85440. Puerto Lopez, E shore Bahia Tucacas: MCZ 81554. 
Rancheria del Cabo de la Vela: ZMA 14916. Riohacha: 
UMMZ 54799, 54801-07, 54810-13; MCZ 14637. 

^On Barbour's inquiry Boulenger wrote "The Tropidodactylus onca was 
purchased of a dealer (Mr. Cutler) . The locality Dominica is, therefore, 
open to doubt." 



1974 ANOLIS ANNECTENS 9 

\TNEZUELA. Distrito Federal. Near Caracas: USNM 
107321. Falcon. Bahia de las Piedras, Paraguana: RNHL 7708 
(3). Bariinu, Buenavista, Paraguana: ZMA 14917. Cerro de 
Machuruia, E Santa Ana, Paraguana: RNHL 7709. El Mainon 
ca. 5 km N ITrumaco: MCZ 133453. Isthmus of the Paraguana 
Peninsula: MCZ 133456-65. Istmo de Medanos: UCV 272, 
300, 461, 488. Los Algodones, 28 km NW Coro: MCZ 
112386-98. Los Chipes, 41 km W Coro: MCZ 112399-407. 
Medanos de Coro: ILS 743. Paraguana Peninsula: MCZ 
133264-65 (hatched in Panama from females taken in Vene- 
zuela), UCV 485. Parque Los Orumos, Coro: MCZ 139349- 
50. Punta Baroa, Paraguana: UCV 448, 561. Rio Condore, 
vicinity of Urumaco: MCZ 133455. Rio Seco on Caribbean 
between Coro and Urumaco: MCZ 132735. Urumaco: MCZ 
132734. Monagas. San Antonio de Maturin: MCZ 14648. 
Margarita Island. Boca del Rio: ILS 578. Between El Agua 
and Puerto Fermin: MCZ 109014, 110068-70. Near El Agua 
on road from Punta de Piedras to Porlamar: MCZ 110064. 
Ensenada de la Guardia, Laguna Arestinga: MCZ 110067. 
Guacuco: UCV 364, USNM 139072, MCZ 110057. Laguna 
Arestinga: ILS 102. Las Morites: ILS 1208. Las Robles: 
USNM 79226-27. "S Las Robles, Porlamar: RNHL 7710 (3). 
Matasiete: ILS 584. Morro de Moreno: RNHL 7711. Porla- 
mar: ZMA 14918 (2). Plantio oeste de la Asuncion: ZMA 
14915 (2). Three kilometers west of Porlamar: MCZ 110397. 
Salamanca: ILS 561, 1231. Sucre. Cumana: KU 117080. 
2.5 km SW Cumana: KU 117079. 3 km SW Cumana: KU 
104369-70. Zulia: south of Paraquaipoa, W side Lago de Mara- 
caibo: MCZ 139352. 

Many of these localities are coastal, but although Collins 
belie\'es onca to be a beach animal on Margarita Island, some 
verified continental localities are well inland {e.g., Urumaco, 
Falcon, Venezuela). x\ll localities, however, are extremely arid 
lowland, usually within the zone called in the Holdridge terms 
adopted by Ewel and Madriz (1968) for Venezuela "monte 
espinoso tropical." A few records appear to lie in an adjacent 
zone, "monte muy seco tropical." A few lie outside e\'en this 
zone, i.e., USNM ^7321 "near Caracas" and MCZ 14648 "San 
Antonio de Martin." These, howe\'er, are very imprecise locali- 
ties. Figure 5 shows the distribution of "monte espinoso tropical" 
and "monte muy seco tropical" for Venezuela according to Ewel 
and Madriz. The Colombian localities are similar. 

Howe\'er, the observations of the field party in the summer 



10 BREVIORA No. 421 

of 1973 suggest that the requirements of onca are more specific 
than just the zone "monte espinoso tropical," Search for addi- 
tional specimens of A. annectens led us into zones clearly within 
the mapped areas but in which onca was apparently absent. 
Anolis auratus was taken in these areas. (See the ecological 
remarks below.) 

Ecology 

The relictual digital pad of annectens would seem to imply a 
somewhat greater arboreal adaptation than that of onca. But 
how terrestrial is onca? 

No more recent obser\^er supports the apparent implication of 
Ruthven's (1922) statement that onca uses burrows. On Mar- 
garita Island Collins (1971) looked particularly into this point. 
He remarks: "At times, a specimen being pursued would run 
into a large hole in the sand opening into a tunnel. It should 
be noted, however, that these holes are resting places made by 
ghost crabs {Ocypode) and are not dug by Tropidodactylus. 
It should also be noted that this was a rather infrequent mode 
of escape, used by the lizard only when almost completely ex- 
hausted." Collins points out that onca does climb when the 
vegetation permits this. Where the vegetation was only a mat 
of vines and branches, onca would clamber over or into this. 
However, "in the area just north of Punta Montadero where 
Mallotonia, a woody-stem plant, is dominant, the animal's be- 
havior was very different. Here, when sighted, the lizard was 
always on the ground. When pursued, the majority of animals 
observ^ed would merely run among the ground cover. A few 
specimens, however, were observed to climb the Mallotonia, 
some to a height of 30.0 cm. Their climbing was clumsy and 
ineffective." 

Collins also took one animal sleeping on a branch of a low 
bush. 

On the continental mainland the observations of Carlos Riv- 
ero-Blanco in July and August, 1970, are very useful. He re- 
ports nine specimens taken on trunks of planted trees in a park 
(Parque Los Orumos in Coro) within one meter from the 
ground and two more taken in the same park from low branches 
between one meter and a meter and a half above ground. Else- 
where, in more natural situations, he reports them from piles of 
dry branches and inside hollow dried cardon and cactus branches 
partly buried in sand. He reported, however, that the local 



1974 



ANOLIS ANNECTENS 



11 



CARIBBEAN SEA 




00 200 



Figure 5. Map of the distribution of A. onca. Shading shows two vege- 
tational zones in Venezuela (after Ewel and Madriz) : black :=. "monte 
espinoso tropical;" cross-hatched = "monte muy seco tropical." + marks 
known localities for onca. 



people said that onca could be seen on the branches of a local 
spineless euphorbiacean. 

One of the animals obtained by the Patterson party in July 
to August, 1972, had been taken on the outside wall of the 
doctor's house in Urumaco. Again, most specimens observed 
were among the branches of piles of dead plants buried in sand 
( at Rio Seco, one to a pile ) . In another area one specimen was 
seen lying motionless on a cobble in the full sunlight. Another 
in still another area was seen on open ground in full sunhght, 
\'ery cryptically colored and detected only by its motion. 

The November 1972 party found males widely spaced out on 
top of the pipe line that runs much of the length of the Isthmus 
of the Paraguana Peninsula. Some were displaying. Others had 
climbed to the top of posts, including fence posts. The re- 
mainder, taken by day, including all females and the one juven- 
ile, were on the ground in bare open spaces. None were seen 



12 BREVIORA No. 421 

in vegetation. Only one individual -- a female — was taken at 
night, sleeping on a low bush less than a foot above the ground. 

The August 1973 field party found onca primarily inside the 
low thorn bushes that are very characteristic of the Paraguana 
Peninsula, apparently coming out of the depths of these early 
in the day and clambering around within these bushes much 
more often than outside of them. Individuals were indeed seen 
on the ground and both returning to and emerging from the 
thorn bushes, but less frequently. Males were seen on the pipe 
line and on fence posts but were not seen perched on rocks in 
open sun in August as they had been so often in November. 
The small thorn bushes were shared to some extent with young 
Cnemidophorus lemniscatus, which climbed skillfully within and 
on top of the bushes. As during the earlier visit to the Para- 
guana, no onca were seen under or on the occasional large, quite 
extensive thorn bushes. 

The small thorn bushes of the Paraguana Peninsula provide 
a very dense matrix in which climbing without adhesive pads is 
obviously easy. The compact bases masked by grass also provide 
places of concealment for onca and very probably sleeping sites. ^ 

The August 1973 party searched for onca and annectens in 
many areas between Coro and Maracaibo, but only located onca 
again S of Paraguaipoa on the east side of the Goajira Peninsula 
( = the west side of Lago de Maracaibo ) . This area closely 
matched the Paraguana Peninsula in appearance and especially 
in the character of the vegetation, inchiding the sparse cover of 
thorn bushes of small to moderate size. 

Anolis auralus was repeatedly observed in areas in which onca 
was lac king and never where onca occurred. It is clear that 
auralus is less stenotopic than onca. It has been seen in lush 
grassland, abundantly on a fence row beside a cattle pasture, and 
sparsely in bare and harsh thorn scrub, often in situations that 
seem climatically more rigorous than those from which onca is 
known. 

Aridity is certainly not the factor determining the presence of 
onca. A special vegetational structure does seem characteristic 
but there is another feature that may be even more important. 
The notes by Rivero-Blanco call attention to the constant high 
wind in the areas in which he observed onca. The November 
1972 and August 1973 field parties also found the winds an 

further data on the ecology, including thermal ecology, of onca will be 
presented by Kenneth Miyata. 



1974 ANOLIS ANNECTENS 13 

impressive feature of the Paraguana isthmus. The onca locality 
on the east side of the Goajira Peninsula was similarly windy. 
The Patterson group, working well inland at Urumaco, were 
constandy buffeted by wind also. Such winds may be a real 
hazard and difficulty for lizards, preventing any strongly arboreal 
adaptation, and wind in combination with aridity and sparse 
\egetation may delimit the habitat of onca. 

Discussion 

The majority of iguanid lizards have infradigital scales with 
multiple longitudinal keels. Tropidodactylus onca in this regard 
appears by "the rule of parsimony" to have retained a primitive 
condition. Why then do Etheridge, Gorman and myself con- 
sider onca the derived extreme in anoles rather than the most 
primiti\e surviving species? The hypothesis that a reversal of 
evolution has produced a rather perfect simulacrum of a primi- 
tive character state seems prima facie less plausible and more 
complicated than a view that accepts an apparently primitive 
character as genuinely so. 

The argument is in fact a simple one : in no other regard does 
onca seem primitive. In every character that Etheridge's skeletal 
analysis regards as important, onca stands closest to the most 
deri\^ed members of the beta section of Anolis. Etheridge ( 1960: 
60) comments: "Except for the absence of specialized lamellae, 
it is in no way distinguished from other anoles. Other features 
of the genus, e.g. the absence of both splenial and angular, ab- 
sence of pterygoid teeth, reduction of the parasternum ( = in- 
scriptional ribs, Etheridge, 1965) etc. indicate that ''Tropido- 
dactylus" is a specialized rather than a primitive anole. Accord- 
ing to Ruthven (1922), the genus is strictly terrestrial, yet all 
other features which mark the anoles as arboreal lizards are 
present. Evolutionary loss of the anoles' specialized lamellae, 
rather than retention of the pre-anole condition, probably offers 
the most reasonable explanation of the [loss of] lamellae in 
Tro pidodactylus ." 

In karyotype also onca departs very much from the 1 2 macro- 
chromosome-24 microchromosome pattern that occurs repeatedly 
in primitive anoles, other diverse groups of iguanids (and in 
other lizard families) and is believed to be primitive for the 
Sauria generally (Webster, Hall, and Williams, 1972). The 
primitive karyotype is found in many members of Etheridge's 
alpha section of Anolis but in no betas, and, as Gorman (1969) 



14 BREVIORA No. 421 

has noted, onca belongs karyotypically, as in skeletal characters, 
to one of the more highly derived groups of beta anoles. 

Two external features are very characteristic of most Anolis — 
the throat fan or dewlap and the adhesive pad with microscopic 
hairs. Both are sometimes reduced within the genus (Williams, 
1963). Both onca and annectens, however, have the dewlap 
very large and very mobile, extremely well developed. A. onca 
is known to use the dewlap very actively (observations of the 
field party in November 1972), flashing it repeatedly, a derived 
and not a primitive feature (Rand and WiUiams, in prepara- 
tion).^ Of the two most basic anole characters, it is only the 
second — the adhesive pad — that is absent in onca and tran- 
sitional in annectens. 

Some of the species that show the first stages of the degrada- 
tion of the digital pad have been separated taxonomically as the 
genus Nor ops. Schmidt (1939), describing the Mexican species 
A. barkeri, called attention to the difficulty, made obvious by 
more than one generic assignment for several of the species, of 
making consistent distinctions between the genera Anolis and 
Norops. Schmidt himself, though he placed barkeri in Anolis, 
recorded the terminal phalanges of barkeri as "less distinctly set 
off from the widened portion than in the normal Anolis.'' 

Moreover, it is now clear that any definition of Norops based 
on digital features includes species that cannot be closely related. 
Anolis aequatorialis and A. mirus of the trans- Andean regions of 
Ecuador and Colombia have Norops-typc digits but are mem- 
bers of the alpha subdivision of the genus (Etheridge, 1960; 
Williams, 1963) and hence are on the other side of a basic 
dichotomy within anoles from Cuban A. ophiolepis, Mexican 
A. barkeri, A. tropidonotus, Colombian A. notopholis. central 
Brasilian and northern Bolivian A. meridionalis, and northern 
South American and Panamanian A. auratus, all anoles with 
Norops-type digits (or an approach to them but belonging to 
Etheridge's beta subdivision ) . 

Even within the beta subdivision the species showing the 
Nor ops-type condition are not closely related to one another. 
Figure 6 adapts Etheridge's 1960 figure of beta anole relation- 
ships to show the independent origin of the species of ''Norops.'' 
The numerals refer to the number of attached and free inscrip- 
tional ribs; both the total number and the number of attached 
ribs tend to decrease from primitive to advanced forms. 

^Dewlap "flashing" is very characteristic of the possibly related forest 
species, Anolis chrysolepis. 



1974 



ANOLIS ANNECTENS 



15 



" N ro p s" phi o]e p[s 



"Tro pidodact y lus " onca 2 : 2 




MAINLAND 
BETAS 



WEST INDIES 
BETAS 



Figure 6. A dendrogiam of relationship within the beta anoles. Modified 
from Etheridge (1960) . 



16 



BREVIORA 



No. 421 





a. 



rW 




e. 




f. 



Figure 7. (from Collette, 1961) . Feet of five Cuban and one mainland 
species of Anolis showing lamellae on the third toe of the left hind foot: 
(a) alutaceus, (b) angusticcps, (c) sagrei, (d) caroUneusis, (e) porcatus, 
(f) eqiiestris. Not to scale. 



1974 ANOLIS ANNECTENS 17 

Phylooeny apart, Anolis species can be arranged in a sequence 
showing clear morphological stages in retrograde evolution. 

1 . Narrowing of the digital dilations. 

^Vithin any local Anolis fauna of more than a few species, 
there are several conditions of the adhesive pads which Collette 
(1961) has related to "arboreality." The broadest digital pads 
are found in those species — "crown," "trunk-crown" and 
"twig" anoles of Rand and Williams (1969) — which live high 
in the trees or use twigs and leaves as perches {e.g., A. porcatus 
and A. equestris in Figure 7e, f [copied from Collette, 1961]). 
There is also some correlation with size, but those species spe- 
cializing on the lower trunks and the ground — "trunk-ground" 
anoles of Rand and Williams (1969) — have strikingly nar- 
rowed pads although they may be larger than some of the com- 
pared species [e.g., A. sagrei in Fig. 7c) . 

2. Reduction of the number of digital lamellae. 

While there is an evident functional difference between a wide 
and a narrow pad in terms of area of adhesive surface, it is not 
functionally obvious what the number of transverse smooth 
"lamellae" has to do with adhesion, especially since many of the 
lamellae in those species with the highest numbers are far distal, 
crowded, small and much narrowed {i.e., at the tapering distal 
end of the pad ) . It is, however, an empirical generalization 
(and not only for Anolis; cf. Hecht, 1952 for the gecko Aristel- 
liger) that the number of lamellae has a positive correlation with 
size and with climbing efficiency. Correspondingly, those anole 
species which climb least and use the ground more show fewer 
lamellae than species of the same size with more arboreal habits. 
Again contrast A. sagrei in Figure 6 with A. porcatus. 

3. Loss of distinctness of the anterior margin of the pad {that 
part under phalanx ii) as against the scales under phalanx i. 

This is the character — the loss of "raised" character of the 
pad — that has classically defined Nor ops {e.g., Boulenger) (see 
Fig. 3 center: ''Nor ops" auratus) and is the maximal degree of 
dedifferentiation of the pad seen except in annectens and onca. 

The functional meaning of this stage is again unclear. But it 
should be pointed out again that the phenomenon is not anoline 
only and that genera have classically been recognized in the 
Gekkonidae on whether the claw arises at the end of the ad- 
hesive pad or "within the pad," i.e., dorsal to it, in the latter case 
providing the pad with a projecting lip just as in Schmidt's 
"normal Anolis." 

4. The fourth and next to final stage in this retrograde series 



18 BREVIORA No. 421 

is found in annectens. As an intermediate between "Nor ops'' 
and Tropidodactylus it is interesting and perhaps unexpected. 
In annectens the scales under phalanx iii are no longer either 
wide or smooth; they are instead narrow and keeled. Under 
phalanx ii, however, there is a residual pad, very narrow, it is 
true, and the lamellae few in number, but still recognizably a 
remnant of the classic anoline pad. The area under phalanx ii 
is in any anole the region of the pad's maximum width (and 
presumed effectiveness). One must assume that there is still 
some selective value to the presence of a minimal adhesive pad 
in annectens. However, the partial reversion to keeling in an- 
nectens and the total reversion in onca may, perhaps, be more 
easily understood in terms of morphogenetic patterns than in 
terms of direct function in the environment: supradigital scales 
are usually keeled in Anolis; unkeeled scales there are excep- 
tional. The modified scales underneath the digit — the adhesive 
pad — are obviously a specialized and limited morphogenetic 
field. The distinctness and perfection of this field must be main- 
tained by a continuing functional need greater than the cost in 
ontogenetic complexity of maintaining the speciaUzed field. A 
reversion to the keeled condition of the infra-digital scales, first 
under phalanx iii and then also under phalanx ii, may therefore 
be no more than the spread of the morphogenetic field of the 
supradigital scales around and under the digit once the utility — 
i.e., the selective value — of and hence the need for local dif- 
ferentiation of very specialized adhesive lamellae has diminished. 

5, The culmination of the retrograde series in onca is in one 
regard imperfect. Hatchling onca have what appear macro- 
scopically to be lamellae under phalanges ii and iii, not keeled 
scales. First discovered in the collection of the Leiden Museum, 
the only preser\^ed collection to have any very small specimens, 
it is now confirmed on hatchlings from eggs laid by captive 
female onca in Panama. 

The "lamellae" of onca hatchhngs are astonishing enough to 
require histological study. How closely do these lamellae match 
the lamellae of "normal" Anolis? Hatchhngs and near hatch- 
lings 27-30 mm in snout-vent length show "lamellae"; juveniles 
just a few millimeters larger (34 mm, 41 mm) already show 
keeled infradigital scales. How is this sharp ontogenetic change 
accomplished? 

A proper study of this question would be a digression here. 
The problem has been referred to P.F.A. Maderson and he will 
be reporting on it. Some of his preliminary observations are. 



1974 ANOLIS ANNECTENS 19 

howe\'er, germane at this time. The "lamellae" of hatchling 
one a are pseudo-lamellae without the "hairs" (spinules) of the 
true lamellae of an Anolis adhesive pad. They also lack the 
spikes characteristic of larger juveniles (almost equal 34 mm 
snout-vent length) and of adults of onca. In contrast annectens 
has under phalanx ii anoline hairs and the lamellae have the 
free distal edge that is characteristically anoline. 

Hatchling onca, thus, though they seem superficially very dif- 
ferent, are on their way to the adult onca infradigital condition. 
The lamellar field, to return to that interpretation of the em- 
bryological basis of these several conditions, is already extremely 
weakened at the time of hatching and soon thereafter is wholly 
substituted for by the field that produces spikes and keeling. 

We have here emphasized a morphological series. The onca 
hatchling is in this regard an intermediate in the series but a 
very difTerent intermediate from adult annectens. The onca 
hatchling already shows a breakdown of the lamellae and ad- 
hesive pad and in the adult the breakdown is total. Annectens 
is on another pathway. The pad under phalanx iii — always in 
Anolis the least significant portion of the total adaptation — has 
in annectens gone completely; retrograde evolution is for this 
area complete. But under phalanx ii the pad is only narrowed 
and the lamellae reduced in number; the latter are still fully 
pilose, presumably still fully adhesive. A habitat for annectens 
more genuinely "arboreal" than that of onca does seem plausible. 

ACKNOW^LEDGMENTS 

Work was supported by National Science Foundation grants 
B 1980 IX and GB-37731X. I am grateful for assistance in the 
field to A. Ross Kiester, A. Stanley Rand, Jane Peterson, Ken- 
neth Miyata, and Richard Salvato. The Curators at the Field 
Museum of Natural History (fmnh), the United States National 
Museum (usnm), Kansas University (ku), the Universidad 
Central de Venezuela (ucv), the Zoologisches Museum Amster- 
dam (zma), and the Rijksmuseum van Natuurlijke Historic 
Leiden (rnhl) have generously loaned material. 

References 

Aleman, G. C. 1952. Puntes sobre reptiles y anfibios de la region Baruta- 
El-Hatillo. Mem. Soc. Cienc. Nat. La Salle, 12: 11-30. 

• . 1953. Contribucion al estudio de los reptiles y batracios 

de la Sierra de Perija. Mem. Soc. Cienc. Nat. La Salle, 13: 205-225. 



20 BREVIORA No. 421 

Barbour, T. 1914. A contribution to the zoogeography of the West Indies, 
with especial reference to amphibians and reptiles. Mem. Mus. Comp. 
ZooL, 44: 205-359. 
BouLENGER, G. A. 1885. Catalogue of the lizards in the British Museum 

(Natural History) 2: xiii + 497 pp. London. 
CoLLETTE, B. 1961. Correlations between ecolog\^ and morphology- in ano- 

line lizards from Havana, Cuba, and southern Florida. Bull. Mus. Comp. 

Zool., 125: 135-162. 
Collins, J. 1971. Ecological observations on a little known South Ameri- 
can anole: Tropidodactylus onca. Breviora, No. 370: 1-6. 
Etheridge, R. 1960. The relationships of the anoles (Reptilia: Sauria: 

Iguanidae) : an interpietation based on skeletal morphology, xiii + 

235 pp. University Microfilms, Ann Arbor, Michigan. 
. 1965. The abdominal skeleton of lizards of the family 

Iguanidae. Herpetologica, 21: 161-168. 
EwEL, J. J., AND A. Madriz. 1968. Zonas de Vida de Venezuela. Ministerio 

de Agricultura y Cria, Caracas. 265 pp. 
Gorman, G. C. 1969. Chromosomes of three species of anoline lizards in 

the genera AnoUs and Tropidodactylus. Mammalian Chromosomes 

Newsletter, 10: 222-225. 
Hecht, M. K. 1952. Natural selection in the lizard genus AristelUger. 

Evolution. 6: 112-124. 
Hiller, U. 1968. Untersuchungen zum Feinbau und zur Funktion der 

Haftborsten von Reptilien. Z. Morph. Tiere. 62: 307-362. 
Hummelinck, p. \\L 1970. A survey of the mammals, lizards and mol- 

lusks. Fauna of Curacao, Aruba, Bonaire and the ^'enezuela Islands. 

Vol. 1: 59-108. 
Lillvwhite, H. B., and P. F. A. Maderson. 1968. Histological changes in 

the epidermis of subdigital lamellae of AnoJis carolinensis during the 

shedding cycle. J. Morph., 125: 379-402. 
Maderson, P. F. A. 1970. Lizard glands and lizard hands: models for 

evolutionary study. Forma et Functio, 3: 179-204. 
Marcuzzi, G. 1954. Nota.? sobre zoogeografio y ecologia del medio xero- 

filo venezolano. Mem. Soc. Cienc. Nat. La Salle, 14: 225-260. 
Osgood, W. H. 1912. Mammals from western Venezuela and eastern 

Colombia. Field Mus. Nat. Hist., Zool. Scr., 10: 29-66. 
O'Shaughnessv, a. W. E. 1875. List and revision of the species of Anolidae 

in the British Museum collection, with descriptions of new species. 

Ann. Mag. Nat. Hist. 15(4): 270-281. 
Rand. A. S.. and E. E. Williams. 1969. The anoles of La Palma: aspects 

of their ecological relationships. Breviora, No. 327: 1-19. 
RtiBAL, R.. AND \\ Ernst. 1965. The structure of the digital setae of 

lizards. J. Morph., 117: 271-294. 
RiTHVFN. A. G. 1922. The amphibians and reptiles of the Sierra Nevada 

de Santa Marta, Colombia. Misc. Publ. Mus. /ool. \ri'h.. 8: 1-69. 
Srii\TiDT. K. P. 1939. A new lizard from Mexico, with a note on the 

genus Voro/K. Field Mns. Xat. Hist.. Zool. Scr., 24: 71 0. 



1974 ANOLIS ANNECTENS 21 

Webster, T. P., W. P. Hall, and E. E. Williams. 1972. Fission in the 
evolution of a lizard karyotype. Science, 177: 611-613. 

Williams, E. E. 1963. Studies on South American anoles. Description 
of Anolis mirus, new species from Rio San Juan, Colombia, with com- 
ment on digital dilation and dewlap as generic and specific characters 
in the anoles. Bull. Mus. Comp. Zool., 129: 463-480. 

1969. The ecology of colonization as seen in the zoo- 
geography of anoline lizards in small islands. Quart. Rev. Biol., 44: 
345-389. 



' ' U\ ^ r I <_) T I y~i 



^CJ 



B R E V I R A 

Mii^^^^^^ip^^^lQ^^iiiparatiYe Zoology 

LIBRARY 



us ISSN 0006-9698 



CAMBRiDAftRNfi^^.19749 March 1974 Number 422 

'^Ag^ffith AMERICAN A NOUS: 
+t¥ftge^NJE\V SPECIES RELATED TO 
ANOLIS NIGROLINEATUS AND A. DISSIMILIS 

Ernest E. Williams 

Abstract. Three new Anolis species are described from widely scattered 
localities in Colombia and Venezuela. Together with Anolis nigrolineatus 
and Anolis dissimilis they appear to represent a natural subgroup of the 
punctatus group of South American alpha anoles. 

The lizard fauna of South America is poorly understood but 
more than that it is little known. It is, for example, very prob- 
able that there are many lizard species to be discovered in the 
continent's remoter and more obscure areas. The three new 
anoles here described are cases in point: they are from areas 
quite remote or obscure - — one from a small river valley in 
Santander and the poorly known states of Tachira and Trujillo 
in Venezuela, another from a camp in remote Caqueta in 
Colombia, and still another from a mission in the delta at the 
mouth of the Orinoco. 

More interesting, however, than the existence of new species 
in little explored areas is the close resemblance of these newly 
discovered, perhaps isolated anoles to species occurring at very 
great distances from them. The most extreme instance is the 
similarity of the anole from the mouth of the Orinoco to a form 
from Madre de Dios Province in Peru. However, the distances 
between the other forms that must be compared are relatively 
small only in the context of the immensity of South America. 

Even in South America it is quite unusual to be compelled to 
describe related species from such small samples as are available 
for the three new forms (one, one and five), especially when 
these are spread over so wide an area with no series available 
for any locality. This may point to a special difficulty pecuUar 
to small arboreal species. The fauna of open formations is usu- 



2 BREVIORA No. 422 

ally obtainable in some appreciable numbers wherever it occurs. 
The species of forests are rarer or more difficult to obtain, but 
most probably both. Those elements of the forest fauna that 
occur well up in the trees or at least in thick \'egetation are likely 
to be the last to be known. On morphology and affinity, al- 
though only for one is anything known directly of the ecology, 
the present three new species appear to belong to this most diffi- 
cult group. 

All three anoles are so close to Anolis nigrolineatus and Anolis 
dissimilis (Williams, 1965) that they, like these, must be as- 
signed to the punctatus group of the alpha section of South 
American anoles. 

A. nigrolineatus (Williams, 1965) was described from two 
specimens, both with questionable localities in southeastern Ecua- 
dor. Two additional specimens have since been discovered in the 
collections of the University of Michigan. These not only provide 
the first good locality for the species (Playas de Montalvo, Prov. 
Los Rios, Ecuador) but provide a better comparison with the 
new but very closely related species from eastern Colombia and 
western Venezuela which I call : 

Anolis nigro punctatus new species 

Holotype: ILS 21, an adult male. 

Type locality: El Diamante, Norte de Santander, Colombia. 

Paratypes (all adult females). ILS 20: Toledo, Norte de 
Santander, Colombia; MCNC 5395, Villa Paez, Edo Tachira, 
Venezuela; MCZ 136175, Quebrada Honda on road from Tru- 
jillo City to San Lazaro, Edo Trujillo, 4700 feet. 

Diagnosis. Close to A. punctatus (cf. the slightly swollen snout 
in the male) but differing in color and squamation. Closer still 
to A. nigrolineatus but difTering in wider head, apparently larger 
size (male 72 mm in snout-vent length rather than 46 mm), in 
the absence of the narrow middorsal black hne and of the broad 
black spot in the dewlap. Nostril without a differentiated an- 
terior nasal scale ( Fig. 1 ) . An apparently greater number of 
lamellae under phalanges ii and iii of the fourth toe (21-22 
rather than 18-19). 

Description. (Paratype variation in parentheses.) Head: 
Head scales flat, obscurely wrinkled. Seven scales (7-10) across 
snout between second canthals. Five scales (6-8) border rostral 
posteriorly. Circumnasal scale separated from rostral by one 
scale (or in contact). Four scales between supranasals. Snout 



1974 



THREE NEW ANOLIS SPECIES 




Figure 1, Anolis nigropunctatus Holotype. Dorsal view of head. 



,-«:2S?p?c)0' 




Figure 2. Anolis nigropunctatus Holotype. Lateral view of head. 



BREVIORA 



No. 422 




Figure 3. Anolis nigropunctatus Holotype. Underside of head. 



somewhat swollen, protuberant, overhanging lower lip (snout 
not swollen in ?). 

Supraorbital semicircles separated medially by 2 scales (2 or 1 
or in contact) and from the supraocular disks of each side by a 
single row of subgranular scales. Supraocular disk of 9 (8-12) 
indistinctly wrinkled scales. Supraciliaries 1-2, continued pos- 
teriorly by granules. Canthus distinct, canthals 5 (5-6), second 
and third canthals longest (third longest). Loreal rows 5 (4-5), 
uppermost largest (uppermost largest or subequal) . 

Temporals and supratemporals granular, grading into enlarged 
scales surrounding interparietal (obscure in second female), 
which is smaller than the small round ear (almost equals ear) 
and separated from the supraorbital semicircles by three (1-4) 
scales. Several of the scales surrounding interparietal larger than 
that scale (or 2/3 that size). Scales posterior to interparietal 
grading gradually into dorsal granules. No enlarged supratem- 
poral rows (indistinct supratemporal rows). 

Suboculars weakly keeled, in contact with supralabials, grad- 
ing posteriorly into the supratemporal granules and anteriorly 
separated from canthals by one scale. Seven supralabials to 
center of eye. 

Mental semidivided, each part almost as wide as deep (wider 



1974 THREE NEW ANOMS SPECIES 5 

than deep), the whole in contact with 3 (4) throat scales 
between large, smooth sublabials which indent it. Sublabials 
enlarged, two (3) in contact with infralabials. Gular scales 
smallest medially, grading laterally toward sublabials. 

Trunk: Middorsal scales not differentiated from flank scales 
(two middorsal rows slightly enlarged), obtusely keeled. Ven- 
trals larger, smooth, quadrate, imbricate, in transverse rows (not 
imbricate). Lateral chest scales obtusely keeled (smooth). 

Dewlap: Large (smaller in ?, extending only between fore- 
limbs), extending nearly to middle of belly. Scales at the edge 
much longer than ventrals (in ? smaller than or equal to ven- 
trals). Lateral scales narrow, elongate, in well-spaced rows 
(close packed in $) , separated by naked skin. 

Limbs and digits: Scales on limbs smooth or unicarinate, 
largest on both arm and hind limb (smaller than ventrals). 
Supradigital scales multicarinate. Twenty-one (22) scales under 
phalanges ii and iii of fourth toe. 

Tail: Compressed, without verticils or dorsal crest. Two 
distinctly keeled middorsal rows; the ventralmost two rows even 
more distinctly keeled. Greatly enlarged postanals (absent in 
9) present. Scales behind vent smooth. 

Color (as preserved) : d above brown, irregularly punctate 
with black; below light brown with a few small lateral black 
spots. Dewlap, both scales and skin, light. $ same as above 
except with a broad middorsal zone light brown, mottled and 
lined with grey and dewlap with light scales and pigmented skin. 
Size: Type (snout-vent length) 72 mm. Paratypes: 60, 56, 
55 mm. 

Comment. A. nigropunctatus (see Table 1) is extremely close 
to A. nigrolineatus but quite adequately distinct. The two newly 
discovered specimens of nigrolineatus (UMMZ 84114-15) fully 
confirm the scale and color characters noted in the original 
description and have the same small size. In the feature of a 
simple single scale (nasal or circumnasal scale) surrounding the 
nostril, I regard nigropunctatus as more primitive than nigro- 
lineatus. The scale called "anterior nasal" in the latter I believe 
to be a modification of a scale originally anterior to that sur- 
rounding the nostril, now become enlarged and triangular, over- 
lapping the anterior margin of the primitive circumnasal scale. 
The higher number of toe lamellae in nigropunctatus accord 
with its larger size. 

Ecological notes are available only for MCZ 136175 for which 
J. A. Rivero records: "On leaves three feet from the ground at 
edge of road near a stream." 



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BREVIORA 



No. 422 







'i^tidtcQ^V^^^Zt^-Jt^----'^ 



Figure 4. Anolis caquetae Holotype. Dorsal view of head. 

The two remaining undescribed species appear to be closest 
to A. dissimilis, but the species geographically more remote is 
more similar than that which is spatially intermediate. The latter 
is clearly the primitive member of the series and, coming from 
the upper Rio Apaporis, is within the Amazonian faunal prov- 
ince but in one of the remoter peripheral parts of that region. 
I name it after the Department of Colombia from which it 
comes. 



Anolis caquetae new species 

Holotype: MCZ 131 176, an adult male. 

Type locality: Camp Soratama, Upper Apaporis, Caqueta, 
Colombia. 

Diagnosis. Close to A. dissimilis but without the tail crest 
characteristic of that species and with a different coloration. 

Description. Head: Most head scales smooth, some on the 
anterior snout unicarinate. Scales in frontal depression distinctly 
smaller than surrounding scales. Ten flat scales across snout 
between the second canthals. Eight swollen scales bordering 
rostral posteriorly. Nasal scale anterior to canthal ridge with 
one lower and one anterior scale separating it from rostral (see 
Fig. 5 ) . Seven swollen scales between supranasals. Snout some- 
what swollen, protuberant, overhanging lower lip. 

Supraorbital semicircles separated from each other by a single 
row of small scales, in contact with the supraocular disks, which 
consist of 24-28 enlarged smooth scales grading into granules 



1974 



THREE NEW ANOLIS SPECIES 



M 




Figure 5. Anolis caquetae Holotype. Lateral view of head. 




Figure 6. Anolis caquetae Holotype. Underside of head. 



10 BREVIORA No. 422 

anteriorly, posteriorly and laterally. A single enlarged supracili- 
an^ continued posteriorly by granules. Canthus distinct, canthal 
scales 7, the third canthal largest, then diminishing gradually 
forward. Loreal rows 5, the lowest distinctly the largest. Tem- 
poral and supratemporal scales granular, grading into enlarged 
scales lateral to the interparietal. A weakly indicated double 
supratemporal row of large granules extending posteriorly from 
the orbit. Interparietal very large, much larger than the small 
round ear opening, in contact with the supraorbital semicircles. 
Scales lateral to the interparietal distinctly enlarged, but those 
posterior to it hardly larger than the dorsal granules, about equal 
to the supratemporal and temporal granules. 

Suboculars smooth, broadly in contact with supralabials, 
grading into large granules behind the eye; anteriorly grading 
into loreals. Seven supralabials to the center of the eye. 

Mentals deeper than wide, in contact with 4 throat scales 
between the sublabials. Sublabials large, wide, three to four in 
contact with infralabials. Central throat scales small, not grading 
into sublabials, swollen, \'aguely keeled. 

Trunk: Middorsal scales granular, swollen, smooth, not dif- 
ferentiated from flank scales. Ventrals larger than dorsals, 
weakly keeled, imbricate. 

Dewlap: Dewlap small, scales larger than ventrals, close set. 

Limbs and digits: Hand and foot scales obscurely multicari- 
nate. Largest arm and leg scales unicarinate, those of the arm 
somewhat larger than ventrals. Twenty-two lamellae under 
phalanges ii and iii of fourth toe. Postanals? 

Tail: Tail compressed with two middorsal rows obtusely 
keeled and the two midventral rows larger, sharply keeled. Ver- 
ticils not evident. Lateral caudal scales increasing in size toward 
ventrals. 

Color (as preserved) : Dorsum brown with a narrow black 
vertebral line bifurcating on nape. Broad oblique transverse 
banding of obscure dark blotches, limbs obscurely banded. Belly 
and throat light brown, sparsely punctate with darker. Tail very 
obscurelv banded. 

Size (snout-vent length) : 57 mm. 

Comment. Like a number of South American anoles that do 
not seem closely related {e.g., A. jacare, A. nigropunctatus), 
A. caquetae has a double row of scales surmounting the tail 
rather than the more usual one. This is very different from the 
tail crest of a single row of enlarged triangular scales character- 
istic of A. dissimilis. This difference does not seem, however, a 



1974 THREE NEW ANOLIS SPECIES 11 

bar to the close relationship. A similar if less extreme difference 
exists between A. nigropunctatus and A. nigrolineatus. In other 
details of squamation A. caquetae and A. dissimilis are very 
much alike (Table 1). They differ strikingly, however, in color 
and pattern. The dark dorsal color of dissimilis with the light 
line from supralabials to shoulder has no elements of similarity 
to the middorsal dark line and broken crossbanding of A. caque- 
tae. On the other hand, the vestigial dark line may indicate 
relationship to A. nigrolineatus, which in squamation (Table 1) 
differs most prominently in features associated with the huge size 
of the interparietal in A. caquetae. 

The last species requiring description comes from the delta of 
the Orinoco. I have therefore named it : 

Anolis deltae new species 

Holotype: (MCN) 2031, adult male. 

Type locality: Mission Araquaimujo, Delta Amacuro, Ter- 
ritorio Federal, Venezuela. 

Diagnosis. Very close to A. dissimilis including the presence 
of a distinctive tail crest, but with a blunter, shorter head, a 
differentiated anterior nasal scale, a larger interparietal with 
larger scales surrounding the interparietal and more lamellae 
under phalanges ii and iii of fourth toe. 

Description. Head: Most head scales smooth, swollen, a few 
obtusely keeled. Eight scales across snout between second can- 
thals. Six scales border rostral posteriorly. Anterior nasal scale 
in contact with rostral. Four scales between supranasals. Scales 
in frontal depression smaller than surrounding scales. 

Supraorbital semicircles in contact, separated from the supra- 
ocular disks on each side by one row of scales. Supraocular disks 
of 12-14 strongly enlarged scales. Supraciliaries one on each 
side, continued by granules. Canthus distinct. Canthal scales 6, 
the second and third largest. Loreal rows 4, the lowermost 
largest. 

Temporals and supratemporals subgranular, grading into en- 
larged scales surrounding interparietal. Interparietal very large, 
larger than ear, in contact with supraorbital semicircles. Scales 
behind interparietal grading gradually into dorsal granules. Sub- 
oculars in contact with supralabials, grading posteriorly into 
supratemporal granules, anteriorly separated from the canthals 
by one to two scales. Seven supralabials to the center of the eye. 

Mental wider than deep, in contact with four throat scales, 



12 



BREVIORA 



No. 422 




->t> — '-w'- 



Figure 7. Anolis deltae Holotype. Dorsal view of head. 




Figure 8. Anolis deltae Holotype. Lateral view of head. 



1974 THREE NEW ANOLIS SPECIES 13 



^^ 




Figure 9. Anolis deltae Holotype. Underside of head. 



set in a gentle forward arc between sublabials. Sublabials en- 
larged, two in contact with infralabials on each side. Gular 
scales subequal centrally but grading laterally into sublabials. 

Trunk: A few middorsal rows slightly enlarged, obtusely 
keeled, grading into flank granules. Ventrals larger, smooth, 
quadrate, imbricate, in transverse rows. 

Dewlap: Large, extending nearly to midbelly. Scales at edge 
as large as ventrals. Lateral scales narrow, elongate, in rows 
separated by naked skin. 

Limbs and digits: Largest limb scales unicarinate, almost 
equal ventrals. Supradigital scales obscurely uni- or bicarinate. 
Twenty-four lamellae under phalanges ii and iii of fourth toe. 

Tail: Most of tail missing but a distinct crest on the portion 
present. Enlarged postanals absent. Scales behind vent smooth. 

Color (as preserved) : Straw. A series of broad but vague 
darker blotches middorsally. Obscurer and quite irregular spots 
and mottling on flanks. Belly with vague markings. Above and 
below head and limbs very obscurely mottled. Dewlap skin and 
scales light. 

Size (snout-vent length) : 58 mm. 

Comment. The tail crest of A. deltas and A. dissimilis in 
particular is a highly distinctive common feature. It is entirely a 
crest of slightly raised keeled scales that gives the appearance of 
a serrate upper border to the tail, not at all like the huge tail 



14 



BREVIORA 



No. 422 



80" 



70" 

_J 



60° 



50" 



40° 

1 



A nigrolineatus 

• nigropunctatus 

A caquetae 

O dissimilis 




10' 



—10" 



-20° 



Figure 10. Distribution of the Anolis of the A. nigrolineatus subgroup. 



fins supported by vertebral spines of the considerable number of 
VV^est Indian species that have compressed crested tails — not 
therefore impressive except that it is very unusual in South 
America. Even the South American giants (the latifrons group 
sensu stricto) , though they have compressed tails, lack any sort 
of crest. The closest resemblance in tail type is perhaps provided 
by the anoles of the pentaprion group (Myers, 1971) in which 
the serrate crest, however, is surely convergent, since these are 
beta anoles belonging to quite a distinct section within the genus 
Anolis. 

A. deltae is quite different from dissimilis in color and pattern, 
closer in this to A. caquetae which it resembles also in the 
strongly enlarged interparietal. It differs, however, from both 
species in the enlarged scales behind the interparietal, markedly 
larger than the dorsals. 

Discussion. The fi\'e species that have been discussed here are 
perhaps a natural subgroup — the A. nigrolineatus subgroup — 



1974 THREE NEW ANOLIS SPECIES 15 

of the punclatus species group. They are all allopatric and the\ 
ring changes on just a few characters. If they are such a group, 
there are two series on the basis of affinities and geography — 
an inner series, peripheral to Amazonia proper, in the upper 
reaches of Amazonian tributaries and the Orinoco, and an outer 
series with one species west of the Andes in Ecuador (almost at 
the southern Hmit of Anolis species west of the Andes) and 
another in valleys in the northern and northeastern continuation 
of the Andes in Colombia and Venezuela. 

So far as current information extends, none of these overlap 
with the two larger Amazonian species of the punctatus group 
— A. punctatus itself and A. transversalis. These widespread 
species, which show little geographic variation, lie internal to 
even the inner series of the nigrolineatus subgroup, A. punctatus 
with a very wide distribution in the Brazilian Atlantic forest, 
Amazonia and in the Guianas, A. transversalis at least partly 
sympatric with punctatus in western Amazonia. With South 
American anoles so little known, this apparent geographic pat- 
tern could well be factitious. However, A. punctatus and A. 
transversalis are among the first collected of anole species wher- 
ever they occur. Their absence from the collections that record 
the dissimilis-caquetae-deltae series may therefore be real. 

Acknowledgments 

Research on South American anoles has been supported bv 
NSF grants B- 1980 IX and GB-37731X. I am grateful to Dr. 
Juan Rivero and Dr. Fred Medem for the gift of material, and 
to Brother Niceforo Maria (Instituto La Salle (ILS), Bogota), 
Frof. Ramon Lancini (Museo de Ciencias Naturales (MCN), 
Caracas ) and Dr. Charles Walker ( University of Michigan 
A^useum of Zoology (UMMZ) ) for the loan of specimens. 

Literature Cited 

My^rs, C. W. 1971. Central American lizards related to Anolis pentaprion: 
two new species from the Ckjrdillera de Talamanca. Amer. Mus, Nat. 
Hist., Novitates, No. 2471: 1-40. 

Williams, E. E. 1965. South American Anolis (Sauria, Iguanidae) : Two 
new species of the punctatus group. Breviora, No, 233: 1-15. 



B R E V JUQlK a 

LIBRARY 

iiseiim of Comparative Zoology 



us ISSN 0006-9( 



— — HARVARD 

Cambridge, Mass. 29 March l^^i^HVERSTT^'^^^^^ ^^"^ 



A NEW SPECIES OF PRIMITIVE ANOLIS 

(SAURIA IGUANIDAE) FROM THE 

SIERRA DE BAORUCO, HISPANIOLA 

Albert Schwartz^ 

Abstract. A new species of primitive anole is described from the Sierra 
de Baoruco in the Republica Dominicana. The species is compared with 
its relatives occultus (Puerto Rico) and darlingtoni and insolitus (His- 
paniola) . Data on the ecology of the new species, in relation to A. insolitus 
and A. occultus, are presented. 

On the Antillean islands of Puerto Rico and Hispaniola occurs 
a small group of anoles which has been known from only three 
species, two of which were only very recently discovered and 
named. The earliest discovery of a member of this trio of lizards 
was that of Anolis darlingtoni Cochran, of which the holotype 
and still only known specimen was taken by P. J. Darlington in 
1934 at Roche Croix on the northern slopes of the Haitian Mas- 
sif de la Hotte on the Tiburon Peninsula at an elevation of about 
5000 feet (1525 meters). Cochran (1935) named this species 
Xiphocercus darlingtoni in recognition of its resemblances to 
X. valencienni Dumeril and Bibron from Jamaica. The genus 
Xiphocercus is now in the synonymy of Anolis; the two species 
are' very similar in general habitus and habits but are not closely 
related. Etheridge (1960: 92) stated that although these two 
species were externally similar, they differed in critical osteo- 
logical details (caudal vertebrae, number of attached and float- 
ing chevrons, and presence of autonomic septa). X. valencienni 
was like other Jamaican anoles in osteological characteristics and 
X. darlingtoni Uke several Haitian species. It seemed obvious 
that these two species were erroneously associated at the generic 

^Miami-Dade Community College, Miami, Florida 33167. 



2 BREVIORA No. 423 

level, and that they represented a convergence between repre- 
sentatives of two anoline stocks of Jamaica and Hispaniola. 

The second member of this complex of anoles was discovered 
on Puerto Rico in 1963 by Juan A. Rivero in the Cordillera 
Central near Cerro de Punta at an elevation of 1338 meters. 
Anolis occultus was described by Williams and Rivero (1965) 
from a suite of specimens from various upland Puerto Rican 
localities and at the same time Thomas ( 1 965 ) summarized the 
ecological data and field observations that he had accumulated 
while collecting the majority of the type-series. Later, Webster 
(1969) presented further information on the ecology of this 
forest-dwelling species. 

The third member of the trio was first secured by Clayton E. 
Ray and Robert R. Allen in 1963 at La Palma, La Vega Prov- 
ince, Republica Dominicana, at an elevation of 3500 feet (1068 
meters) in the Dominican Cordillera Central. Anolis insolitus 
was described by Williams and Rand ( 1 969 ) from six specimens 
taken at the type-locality. These authors also made extensive 
comparisons between darlingtoni, occultus, and insolitus, which 
form a small complex of primitive anoles. That they are distinct 
species is unquestioned. But WiUiams and Rand (1969: 10) 
noted that "Certainly the most plausible assumption based on 
current evidence is that darlingtoni and insolitus are geographic 
representatives ... of one stock. This assumption, however, 
leaves the extreme size disparity of these allopatric species with- 
out easy explanation." At the time this statement was written, 
the largest known insolitus had a snout-vent length of 34 mm 
and the holotype of darlingtoni has a snout-vent length of 
72 mm. The allusion of WilHams and Rand to these two species 
as "geographic representatives" is due to the fact that one {dar- 
lingtoni) occurs on the Hispaniolan south island whereas the 
other (insolitus) occurs on the Hispaniolan north island. These 
two terms have come into common usage among herpetologists 
who deal with Hispaniolan amphibians and reptiles, since they 
apply to two island masses, formerly separated, but now joined 
by the low-lying Cul de Sac-Valle de Neiba plain. These two 
islands have, to a large extent, distinctive faunas; there has 
naturally been some invasion and interchange of species, but this 
has been primarily of lowland forms. The montane faunas of 
these two paleoislands remain remarkably distinct today, and it 
is only reasonable to assume that these montane faunas, despite 
a common origin in many cases, have been completely discon- 
tinuous for a very long period. 



1974 Anolis sheplani 3 

Williams and Rand (1969: 10) also pointed out that of the 
21 Hispaniolan species of Anolis, seven had been described 
within the last ten )ears; they also stated that they felt that the 
list of species presented in their summary was incomplete and 
that ''the fund of new information and of new taxa is not nearly 
exhausted, and the need for further collection and study is 
abundantly clear." 

Under the sponsorship of two National Science Foundation 
o-rants (G-7977 and B-023603) between 1968 and 1972, I col- 
lected in the Republica Dominicana; comparable collections 
were made by Richard Thomas in Haiti. In the former country, 
we were successful in securing specimens of two new species of 
Anolis. The description of one of these (Schwartz, 1973) has 
already been completed. Although this species, from the Cordil- 
lera Central, is a large and exceptionally handsome lizard, it 
does not add materially to our knowledge of the Antillean history 
of the genus Anolis. It is a species living in deciduous forest of 
the Central uplands at elevations above 5400 feet (1647 meters), 
and as far as present evidence indicates, it is an endemic Cordil- 
lera Central species of the monticola complex. 

The second species is far more interesting and intriguing. 
This anole is an inhabitant of hardwood forests in the Sierra de 
Baoruco, the easternmost massif of the chain of three montane 
masses on the Hispaniolan south island. It is in the Massif de la 
Hotte, the westernmost of this chain of three ranges, that A. 
darlingtoni occurs. Thus, we now know of two species of this 
group of anoles from the Hispaniolan south island. The doubts 
expressed by Williams and Rand concerning the geographical 
equivalence of darlingtoni and insolitus have been shown to have 
a sound basis, since there is little question that this new species 
is the south island analogue of the north island insolitus, and 
that the larger darlingtoni stands alone among other members 
of the group as a much larger lizard. Details of the relationships 
between all four species will be presented by WiUiams and 
Eth'eridge in a separate publication; it is my aim herein to 
describe the new species, give details of its variation, and com- 
pare it with the three remaining species, as well as to present 
field observations made during 1971. 

The first specimen of this new taxon was obser^^ed by myself 
on the night of 29 August 1971, as it slept on a dry hanging 
\ine under a low \'ine canopy shelter adjacent to the road in the 
Sierra de Baoruco. Its sleeping posture and general configura- 
tion, despite the fact that it was some ten feet (3.1 meters) above 



4 BREVIORA No. 423 

me, attested that it was a species related to A. insolitus and A. 
occultus. Because of the peculiar situation where the lizard slept, 
I was reluctant to make the attempt to secure it. This reluctance 
was due to the fact that I and my companions have spent many 
nights and days collecting in the Sierra de Baoruco since 1963 
without seeing a lizard of this sort. Bruce R. Sheplan was in- 
vited to make the attempt at retrieving the lizard, and he very 
carefully ascended the muddy road cut, crawled gingerly beneath 
the vine canopy without disturbing the vegetation, and handily 
secured the lizard. We later learned that there was no need for 
such care in dealing with this Anolis, since, like insolitus and 
occultus, it is extremely tolerant of any sort of nocturnal disturb- 
ance and determinedly clings to its perch despite disturbances. 
A second specimen was secured later the same evening from a 
similar sleeping situation only 15 feet (4.6 meters) from the first 
individual. Two more visits to the same general area yielded a 
total of 16 lizards: it is obvious that at least locallv this new 
species is not rare, but on the other hand its ecological require- 
ments (and these can be deduced only from its sleeping sites) 
may be extremely rigid. The locality itself is not difficult of ac- 
cess and to my eye is little different from many other regions irt 
the Sierra de Baoruco uplands, areas such as the Las Auyamas- 
Valle de Polo region which have been extensively collected. Still, 
the new species is known only from one fairly circumscribed 
area. In honor of Mr. Sheplan, whose care and interest not only 
were responsible for the first two specimens but also for most of 
the subsequent material, I propose that the new species be named 

Anolis sheplani new species 

Holotype. National Museum of Natural History (USNM) 
194015,' an adult male, from 13.0 mi. (20.8 km)'SE Cabral, 
3200 feet (976 meters), Barahona Province, Republica Domi- 
nicana, taken by Bruce R. Sheplan on 29 August 1971. Original 
number Albert Schwartz Field Series (ASFS) V30309. 

Paratypes. ASFS V30310, same data as holotype; Carnegie 
Museum (CM) 52300, same locality as holotype, 30 August 
1971, D. C. Fowler; ASFS V30326,' USNM 194016-17, CM 
54140-41, American Museum of Natural History (AMNH) 
108822, Museum of Comparative Zoology (MCZ)' 125641-42, 
12.3 mi. (19.7 km) SE Cabral, 3300 feet (1007 meters), Bara- 
hona Province, Republica Dominicana, 30 August 1971, D. C. 
Fowler, A. Schwartz, B. R. Sheplan; MCZ 125691, ASFS 



1974 Anolis sheplani 5 

V30824-26, 12.3 mi. (19.7 km) SE Cabral, 3300 feet (1007 
meters), Barahona Province, Republica Dominicana, 9 Septem- 
ber 1971, A. Schwartz, B. R. Sheplan. 

Diagnosis. A species of the darlingtoni-occultus-insolitus group 
of anoles, distinguished from all other species by the combina- 
tion of: 1) small size (males to 41 mm, females to 40 mm 
snout-vent length) and strong lateral compression; 2) modally 
2 rows of loreal scales (modally 3 or 4 in other species) ; 
3) supraorbital semicircles modally separated by 1 row of scales 
(3 rows in occultus, 1 row in darlingtoni and insolitus) ; 4) su- 
praocular semicircles separated from interparietal scale by 1 
scale on each side (4 scales in occultus, 1 scale in darlingtoni 
and insolitus) ; 5) modally 1 enlarged scale in supraorbital disk 
(no enlarged scales in occultus, 2 in insolitus, 5 in darlingtoni) ; 

6) rostral scale in contact posteriorly with 5 small scales (9 
scales in occultus, 5 scales in insolitus, 6 scales in darlingtoni) ; 

7) 4 distinct canthal scales (10 indistinct small canthal scales in 
occultus, 4 distinct canthals in insolitus, 5 in darlingtoni) ; 8) su- 
pralabials to center of eye 8 ( 10 in occultus, 7 in insolitus, 7 or 8 
in darlingtoni) ; 9) 4—6 scales (mode 5) between second canthal 
scales (9—14 in occultus, 2-6 in insolitus with a mode of 4, 5 in 
darlingtoni) ; 10) a distinct supraciliary row of scales but no 
scale enlarged (no differentiated supraciliaries in occultus) ; 
11) no postorbital, supratemporal, or occipital spines (present 
in insolitus); 12) no distinct supratemporal line of enlarged 
scales (present and the series enlarged and terminating in a spine 
in insolitus); 13) interparietal scale ovoid, much larger than 
external auditory meatus (equal in occultus) ; 14) canthal ridge 
strong (weak in occultus); 15) middorsal scales small, smooth, 
subequal, with a longitudinal series of isolated spine-like scales 
separated by about 6 to 8 small flat scales, no specialized spine- 
like scales on neck (no modified middorsal scales in occultus; 
nape scales slightly smaller than middorsals and no specialized 
spine-Hke scales in darlingtoni; nape scales forming a low nuchal 
crest as far posteriorly as about insertion of forelimbs, followed 
by low rounded and isolated bosses, composed of about 8 small 
rounded scales, the bosses separated by about 5 or 6 small dorsal 
scales in insolitus) ; 16) ventral scales smooth and distinctly larger 
than dorsal scales (about equal in darlingtoni), juxtaposed, in 
often poorly defined transverse rows; 17) dewlap large, slotted 
(= inset), in both sexes, pale peach in males, brown with a 
cream border in females (pinkish gray in both sexes of occultus; 
rich mustard, brown, orange or orange-ocher in both sexes of 



6 BREVIORA No. 423 

insoUtus; color unknown and dewlap not slotted in darlingtoni) ; 
18) limb scales smooth, those on anterior face of thigh as large 
as ventrals (smaller than ventrals in occultus, weakly carinate in 
darlingtoni) \ 19) supradigital scales smooth (multicarinate in 
darlingtoni) ; 20) tail round with a continuation of the e\enly 
spaced middorsal spines, dorsal caudal scales larger than xentrals, 
smooth to weakly unicarinate, ventral caudal scales much larger, 
strongly unicarinate (no dorsal caudal scale modification in 
occultus, dorsal scales very small, granular, ventral caudal scales 
larger, smooth, and smaller than ventrals; dorsal caudal scales 
modified into a series of irregularly spaced large triangular scales 
in insolitus, dorsal and ventral caudal scales unicarinate and ven- 
tral caudals larger than ventral scales) ; 21) a pair of enlarged 
postanal scales in males (none in occultus) ; 22) general colora- 
tion \'ery pale (almost white) but capable of pale tan to dark 
brown phases, or lichenate blotching of these two colors with a 
row of tiny dark brown dots down middorsal line, these dots 
the enlarged median dorsal spinose scales; a small black to dark 
brown nuchal dot and a broad dark sacral U in the pale phase: 
two black radiating lines from the eye onto the temporal region 
and a ventral radiating line from the eye which, \'entrally, forms 
one of a maximum series of five incomplete transverse dark 
brown to black lines crossing the throat, the most posterior at 
the anterior end of the slotted dewlap; venter white. 

Description of holotype. An adult male with the following 
measurements and scale counts: snout-\Tnt length 40 mm, tail 
length 43 mm; 4 canthal scales; 5 snout scales at level of second 
canthal scales; 3 vertical rows of loreals; supraorbital semicircles 
separated by 1 row of scales; 1 scale on each side between the 
interparietal and the supraorbital semicircles; subocular scales 
and supralabial scales in contact; 1 large scale in the supraocular 
disk ; 2 postmental scales ; 6 small scales in contact with the ros- 
tral scale posteriorly; 8 supralabials to center of e^e; 14 sub- 
digital lamellae on phalanges II and III of fourth toe. Colora- 
tion of holotype. When collected at night, very pale tan (almost 
white), but capable of limited metachrosis to pale tan at one 
extreme and dark l^rown at the other; often assuming a lichenate 
blotched pattern of pale tan and dark brown, with a row of tiny 
dark brown dots down the dorsal midline, these dots correspond- 
ing to the indi\idual enlarged and spaced spinose middorsal 
scales; in the pale phase, a black to dark brown nuchal dot and 
a dark broad sacral U; tail banded red-brown and tan, the 
red-brown bands narrow, fi\'e in number including the tail tip, 



1974 Anolis sheplani 7 

and separated by tan interband areas that are twice the width 
of the dark bands; a pair of fine black lines radiating onto the 
temples from the eye on each side, and a fine black line extend- 
ing \'entralh from the eye across the supralabials onto the throat 
where it forms the central of five incomplete dark crossbands 
across the throat, the most posterior of which is at the angle of 
the jaws; dewlap large, slotted, very pale peach, venter very pale 
tan laterally, white centrally. 

Variation. The series of A. sheplani consists of 16 specimens 
of which one (MCZ 125691) has been skeletonized and upon 
which no external counts or measurements were taken. Of the 
remaining 15 lizards, nine are males and six are females. The 
largest male has a snout-vent length of 41 mm (MCZ 125641) 
and the largest female 40 mm (ASFS V30310). Both sexes thus 
seem to reach about the same adult size; males are easily dis- 
tinguished at any age by the presence of a pair of enlarged post- 
anal scales. The series includes four young lizards with snout— 
\'ent lengths between 20 mm and 25 mm. The canthal scales are 
large and clearly delimited and always 4. There are between 
4 and 6 scales across the snout at the level of the second canthals 
( mode 5 ) . The loreal rows are either 2 or 3 ( mode 2 ) . The 
supraocular semicircles are either in contact or separated by 
1 or 2 rows of scales ( mode 1 ) . The scales between the inter- 
parietal and the supraocular semicircles are almost always 1 
bilaterally, although two specimens have 2 scales in this position 
unilaterally. The subocular scales are always in contact with the 
supralabial scales, of which there are between 7 and 10 (mode 
8) to the center of the eye. There is modally only 1 enlarged 
scale in the supraorbital disk, but three lizards have 2 scales 
(the second enlarged but much smaller than its companion) in 
the disk. The postmental scales vary between 2 and 5 (mode 4) 
and there are 4 to 8 small scales (mode 5) in posterior contact 
with the rostral scale. In further discussion of scutellar charac- 
ter§, I follow the schema established by Williams and Rand 
(1969) for this group of anoles. 

Head: Narrow, elongate. Head scales large, smooth, smallest 
anteriorly. Nostril circular, nasal scale separated from rostral by 
3 small oval scales. Rostral scale wide, low, in contact with 4 
to 8 small scales posteriorly. 

Supraorbital semicircles large, weakly con\'ex, the scales 
slightly boss-like, either in contact or separated by 1 or 2 rows of 
smaller scales. A much less distinct row of many small oval 
scales along the supraciliary margin on each side, no elongate 



8 



BREVIORA 



No. 423 




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Anolis sheplani 







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BREMORA 



No. 423 







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1974 Anolis sheplani 11 

siipraciliary scale. Posterior and interior to the supraciliary row, 
3 or 4 rows of small scales or granules of which the most interior 
are largest, surrounding the single (occasionally two) enlarged 
scale in the supraorbital disk. Canthal ridge of 4 scales well 
defined, second canthal longest, diminishing in size anteriorly, 
anteriormost posterior to nostril and separated from it by the 
posterior portion of the nasal scale. Loreal rows 2 or 3, the scales 
varying in shape between elongate rectangular and quadrangu- 
lar. No distinct supratemporal Hne or row of scales. Temporal 
scales small, flat, about 14 between the enlarged postocular 
scales and the external auditory meatus. Supratemporal scales 
flat and gradually larger than temporals, not forming a U-shaped 
crest behind the interparietal region. Interparietal ovoid, very 
much larger than tiny external auditory meatus, separated on 
each side usually by 1 (occasionally 2) scale from the supra- 
ocular semicircles. Scales surrounding interparietal flat, without 
prominent tubercles or spines. External auditory meatus very 
tiny, elliptical, placed far ventrally, just dorsal to the comissure 
of the mouth. 

Suboculars directly in contact with supralabials, anteriorh 
grading into loreals, posteriorly continuous with the enlarged 
postoculars. Seven to 10 supralabials to center of eye. 

Mental large, semidivided, wider than deep, in contact with 
2 to 5 small granular postmental scales; 1 infralabial and 1 sub- 
labial in contact with mental on each side. Throat scales smooth, 
elongate anteriorly, becoming more granular and ovoid posteri- 
orly, gradually merging with the ventral scales. 

Trunk: Dorsal scales small, smooth, slightly larger on flanks, 
and merging with the \entral scales; a middorsal series of in- 
di\idual spinose crest scales, separated by about 6 to 8 unmodi- 
fied dorsal scales, this middorsal series of spinose scales continued 
onto the dorsal caudal midline. Ventrals larger than dorsals, 
smooth, rounded, and in transverse rows that may be slightly 
irregular. 

Dewlap: Large; present in both sexes, slotted (= inset), pale 
peach in males, brown with a cream border in females, scales 
lar2:e and arranged in rows, larger than throat scales and about 
the same size as ventrals; marginal dewlap scales crowded and 
about the same size as throat scales adjacent to dewlap. 

Limbs and digits: Limbs short, tibial length about equal to 
distance from tip of snout to center of eye. Thirteen to 17 lamel- 
lae under phalanges II and III of fourth toe. Scales of limbs 



12 BREViORA No. 423 

smooth, those of anterior surface of thigh sUghtly smaller than 
ventrals. Supradigital scales smooth. 

Tail: Round non-verticillate, with a median series of widely 
spaced spinose scales, their apices directed posteriorly, separated 
from each other bv about 3 to 5 smaller, smooth to weaklv uni- 
carinate dorsal caudal scales. A pair of enlarged postanal scales 
in males. Scales behind vent and around base of tail smooth. 
Four to 6 ventral rows of much enlarged unicarinate caudal 
scales. 

Color in life: The coloration and pattern of A. sheplani have 
been given both in the diagnosis of the species and in the descrip- 
tion of the holotype and need not be repeated in detail. The 
lizards are capable of limited metachrosis (they have no green 
phase) between very pale tan (almost white) while sleeping and 
brown when disturbed or active. In the pale phase there is a 
brown nuchal dot, a broad dark sacral U, and a median dorsal 
series of dark brown to black dots. An intermediate pigmental 
condition involves a lichenate tan-and-brown phase. The dew- 
lap is pale peach in males, dark brown with a cream border in 
females; although the dewlap is well developed in both sexes, it 
is slightly larger in males than in females. 

Comparisons. The diagnosis gives details of comparisons be- 
tween sheplani and the three remaining species of the group 
{darlingtoni, occultus, insolitus) , and these need not be repeated. 
However, there are some salient differences that I wish to em- 
phasize. Of the four species, sheplani most closely resembles 
occultus in snout-vent length; females of both species reach a 
snout-vent length of 40 mm, whereas the largest male occultus 
(ASFS V5489) I have examined has a snout-length of only 
35 mm; Williams and Rand (1969: 13) noted maximally sized 
occultus at 34 mm snout-vent length (sex not stated), but 
Williams and Rivero ( 1 965 : 7 ) gave 42 mm as the size of the 
largest occultus (sex not stated) examined by them. A. sheplani 
is smaller than A. insolitus (maximally sized male 47 mm — 
ASFS V22502; female 44 mm — ASFS V31614), and much 
smaller than A. darlingtoni (holotype male, 72 mm). Of the 
four species, only occultus males lack enlarged postanal scales. 
The spinose or tuberculate head scales, and the supratemporal 
line of enlarged scales which terminates in a spine, are absent in 
sheplani, as well as occultus and darlingtoni; these features are 
distinctive of insolitus. Scales between the second canthals are 
very numerous in occultus (9-14) and very many less in the 
other species, with insolitus hciving 2-6 (mode 4) and sheplani 



1974 Anolis sheplani 13 

4-6 (mode 5). A. darlingtoni has 5 scales between the second 
canthals. Loreal rows are modally 2 in sheplani, 3 in darlingtoni 
and in insolitus, and 4 in occultus. The supraorbital semicircles 
are modally separated by 3 scales (2-5) in occultus, by 1 row 
of large scales in insolitus, by 1 row of small scales (0-2) in 
sheplafii, and by 1 row of small scales in darlingtoni. Scales 
between the interparietal and the supraorbital semicircles are 
modally bilaterally 4 in occultus (range 2-6), and 1 scale in the 
other species (range 0-2 in insolitus, 1-2 in sheplani, 1 in dar- 
lingtoni). The supraocular disks in occultus have no enlarged 
scales, whereas in sheplani there is 1 (occasionally 2) enlarged 
scale in this area, in insolitus 1 to 6 ( mode 2 ) , and 5 in darling- 
toni. Scales posteriorly in contact with the rostral are 6-10 in 
occultus (mode 9), 4-7 in insolitus (mode 5), 4-8 in sheplani 
(mode 5), and 6 in darlingtoni. The canthal scales are poorly 
defined and very numerous (7-12; mode 10) in occultus, 
whereas all sheplani have 4 distinct canthals, insolitus modally 
has 4 distinct canthals (range 3-6), and darlingtoni has 5. 
There are 9-11 supralabials to the eye center in occultus (mode 
10), 6-8 (mode 7) in insolitus, 7-10 (mode 8) in sheplani, and 
7 or 8 in darlingtoni. 

The dewlap color in occultus is pinkish gray, whereas that of 
insolitus varies between rich mustard, brown, orange or orange- 
ocher; in neither of these species is the dewlap color sexually 
dichromatic, whereas the dewlap is strongly sexually dichro- 
matic in sheplani. 

Thomas (1965: 15-16) gave a resume of the color repertory 
of occultus; the pattern of this species consists of a dark cephalic 
figure or interocular trangle; dark radiating eye lines; four zones 
of transverse body banding (scapular, dorsal, lumbar, sacral) ; 
a single or paired lumbar spot; and a fine reticulum of dark lines 
which frequently appears as small ocelli. The ground color of 
occultus varies through shades of gray through olive-brown, 
olive, yellow-green to dirty orange, to a lichenate off-white or 
very light gray and black or very dark gray. In insolitus, the 
dorsum is grayish green or grayish brown, irregularly marbled, 
with a distinctive pale green supra-axillary crescent, a white 
subocular spot, and a black postorbital spot. In life, the supra- 
axillary crescent is extremely clear, and it, plus the black post- 
orbital spot, are ready recognition features of the species. At 
night while asleep, insolitus may often be a very pale tan or 
white, very much in the fashion of sheplani. The coloration of 
darlingtoni in life is unknown, but Williams and Rand (1969: 



14 BREVIORA No. 423 

1 1 ) have an excellent figure showing the basic design of the 
holotype. Conspicuous details of the pattern are a large dark 
postocular blotch and a generally transversely banded (about 
five fragmented bands) dorsal pattern. 

One structural feature is interesting. A. occultus has the 
median dorsal scales unmodified into any sort of spines or crest 
scales. In sheplani, there are isolated spinose scales along the 
dorsal midline, the scales separated widely by small dorsal scales. 
In insolitus, there are low raised bosses that are coxered by 
"rosettes" of scales, slightly larger than their surrounding scales, 
the bosses separated by unspecialized dorsal scales. These raised 
"bosses" with the rosettes of scales become slightly less conspicu- 
ous posteriorly, and on the tail are replaced by laterally com- 
pressed and spaced individual triangular scales as part of the 
same dorsal series. A. darlingtoni lacks specialized middorsal 
scales. 

Field observations. All specimens of A. sheplani were taken 
in a very circumscribed area between 3200 and 3300 feet (976 
and 1007 meters) in the Sierra de Baoruco. The immediate area 
where the lizards were secured is high mesic deciduous forest, 
somewhat modified by the cultivation of coffee and cacao. The 
high original forest trees have been retained as shade cover for 
the cultivated plants. The general aspect is rich, wet, and very 
well wooded. A newly constructed highway ascends the north- 
ern slope of the Sierra de Baoruco between Cabral in the Valle 
de Neiba and the settlements of Las Auyamas and Polo in the 
Baoruco uplands. At a distance of 10.4 miles (16.6 km) south 
of Cabral, an unpaved but quite good road takes ofT to the 
southeast of the main highway and terminates abruptly at the 
settlement of La Lanza. The road apparently formerly went 
from La Lanza to the coastal town of Paraiso, but this section 
is no longer passable. At a distance of between 1.9 and 2.6 miles 
(3.0 and 4.2 km) from the intersection, the road has been cut 
into a gradually sloping mountain side. Below the road there 
are high-canopied cajetales and cacaotales; abo\'e the road, and 
separated from it by a road-cut bank that varies from 2 to 10 
feet (0.6 to 3.1 meters) in height, is an area of second-growth 
trees, saplings, shrubs, and weed and grass patches, the arbores- 
cent vegetation heavily interlaced with li\'ing and dead \ines, 
primarily those of a purple-flowered member of the Con\ol\ula- 
ceae. In many places along this limited stretch of road, there 
are dense mats and curtains of vines; it was within and under 
these mats that A. sheplani was encountered. The species is far 



1974 Anolis sheplani 15 

outnumbered by Anolis hendersoni Cochran, which sleeps in pre- 
cisely the same situations, and one Anolis singularis Williams 
was also found sleeping syntopically with A. sheplani. 

Sleeping sites of A. sheplani are bare twigs and vines within 
and beneath the curtains and mats of vines. The lizards sleep 
exposed and are easily seen since they are very pale. They are 
not easily disturbed by movement of the collector, jostling of the 
\ines, or flashlight. On those rare occasions when an individual 
was disturbed, it opened its eyes, clutched the twig or vine more 
tightly, and, if pressed, moved unhurriedly away from the source 
of disturbance. We never saw A. sheplani either scurry away or 
drop to the ground in the fashion of other anoles when disturbed 
at night. Rather, their reaction to complete disturbance (for 
instance, touching the lizard or breaking the twig or vine to 
collect it) only caused the lizard to cling more tightly to its sub- 
strate. The lowest Hzard was taken at a height of 3 feet, the 
highest 14 feet, above the ground; this gives a sleeping range of 
3 to 14 feet (0.9 to 4.3 meters). It is probable that A. sheplani 
sleeps even higher on vines in the canopy, but at this location 
the trees in general are fairly low (perhaps 20 feet — 6.1 meters 
— average height) and thus the vines are low. It is significant 
that we never encountered A. sheplani below the road in this 
same area, despite suitable vine mats and curtains; on the lower 
side of the road the forest is much less disturbed and the canopy 
is much higher. In neighboring situations, even within a few 
meters, A. cy botes, A. coelestinus and A. distichus were also 
found sleeping. 

It is instructive to compare the sleeping sites and general be- 
havior of A. sheplani with that of A. insolitus and A. occultus. 
I have the impression that insolitus is an inhabitant of much less 
disturbed situations than sheplani. The known localities for in- 
solitus, which now number seven, are invariably gallery forest 
along rixers or streams. At some localities for insolitus, the forest 
has been slightly disturbed by planting of coffee and cacao, but 
in 'general the canopy is high and dense, and vines and lianas 
are abundant and conspicuous (but often quite high). Conse- 
quently, sleeping sites of insolitus are not restricted to sheltered 
spots beneath vine mats or curtains. Regularly, specimens of 
insolitus have been taken completely exposed on the tips of twigs, 
vines, and branchlets, at heights above the ground between Z 
and 25 feet (0.6 and 7.6 meters). On occasion, A. insolitus 
ha\e been taken sleeping on green leafy shrubs rather than on 
bare twigs and vines. At the type locality, however, during a 



16 BREvioRA No. 423 

verv heavy and continuous rain, most insolitus were secured in 
sheltered situations under vine mats or curtains, and two indi- 
viduals were found sleeping on top of each other on a pendant 
vine. In summary, the sleeping sites of A. insolitus are regularly 
much more exposed than are those of A. sheplani. 

Thomas (1965) and Webster (1969) have both commented 
upon the habits of A. occultus in Puerto Rico. Northeast of 
Guayama, Thomas reported occultus "sleeping at night in tangles 
of dead (or leafless) vines and twigs along both sides of the 
path, four to ten feet abo\'e the ground" on a forested hillside, 
and north of Sabana Grande Thomas recorded this species sleep- 
ing at heights of 4 to 15 feet (1.2 to 4.6 meters) on dead vines. 
Finally, south-southeast of Villa Perez, A. insolitus was en- 
countered asleep in the same sorts of situations 5 to 1 2 feet ( 1 .5 
to 3.7 meters) above the ground. Webster reported sleeping 
sites of seven A. occultus at a locality south of Palmer as "long, 
exposed twigs, . . . twigs near leaves, . . . and the upper surface 
of a broad, stiff leaf." Webster also located six additional A. 
occultus sleeping on H\ing twigs near leaves, one on a long dead 
twig, and at the tip of a very long descending branch, and a 
juvenile on a dead fern. Both Thomas and Webster commented 
on the habit of occultus of clinging tightly to twigs when dis- 
turbed; this habit is shared with A. sheplani as noted above. 
The same is true of A. insolitus; on one occasion, we cut from 
the tree the small branch upon which an insolitus slept, and the 
lizard remained clinging to the branchlet during the entire 
operation. On another occasion, a pendant vine upon which an 
insolitus slept was dehberately broken above and below the lizard 
and then accidentally dropped onto the ground in leaf litter and 
herbaceous growth. When the vine was located, the now wide- 
awake insolitus was seen to be still clinging tightly to the vine! 

Remarks. I have little doubt that A. sheplani is more closely 
related to A. insolitus than to A. darlingtoni, despite the fact 
that the latter species occurs on the south island along with 
sheplani (although the sole darlingtoni locality is removed some 
310 kilometers to the west of those for sheplani). It is truly 
puzzling, considering the intensive (albeit local) collecting ac- 
tivity on the Hispaniolan south island in Haiti, most especially 
in the mountains above Port-au-Prince ( Montague Noire, Mome 
I'Hopital) and in the Massif de la Hotte (Les Platons, Castillon) 
that no further specimens of A. darlingtoni have been encoun- 
tered. I suspect that the habits of this species will be found to 
be very like those of the remaining members of the complex; if 



1974 Anolis sheplani 17 

so, then nocturnal collecting with emphasis on dead vines, 
branches, twigs, etc., in sheltered locales may well be the secret 
of securing more A. darlingtoni. Considering the apparently 
very narrow ecological situations that A. sheplani favors, and 
the fact that the uplands of the Sierra de Baoruco in the Las 
Auyamas-Polo region have presumably been well collected since 
the 1920's, there is always the possibility that A. darlingtoni has 
equally stringent ecological requirements that have been over- 
looked or that may be very restricted in the Massif de la Hotte. 
Likewise, I have little doubt that A. sheplani will be encountered 
elsewhere in the Sierra de Baoruco and (or a related form) in 
the Massif de la Selle and its associated ranges. 

The knowledge that the darlingtoni group of anoles occurs on 
both the north and south Hispaniolan islands should spur interest 
in ascertaining the presence of similar species of this small group 
in other Hispaniolan ranges. Most pertinent is the Sierra de 
Neiba, that range which borders the Valle de Neiba on its north- 
ern side, just as the Sierra de Baoruco borders the low-lying 
\'alley on its southern side. If insolitus and sheplani are more 
closely related to each other than either is to darlingtoni, it would 
seem likely that some member of this group of anoles occurs in 
the uplands of the intervening Sierra de Neiba. On this premise, 
we visited that range both during the day and at night during 
1971, but to no avail. The forests are mesic and viney, alto- 
gether suitable situations for members of this group of lizards. 
The canopy is generally high, however, and this may make it 
more difficult to secure related anoles if they occur in this range. 
However, in similar high-canopied forests south of El Rio in the 
Cordillera Central, A. insolitus was easily observed. It may well 
be that there is no member of the darlingtoni group in the Sierra 
de Neiba, but this range is so poorly known herpetologically that 
one cannot with certainty dismiss the absence of a related species 
there. 

The elevational distributions of the four members of the dar- 
lingtoni complex are interesting. A. occultus in Puerto Rico is 
known to occur between elevations of 2300 and about 4389 feet 
(702 and 1338 meters), whereas the known altitudinal ranges 
of the other species are: darlingtoni, 5000 feet (1525 meters); 
sheplani, 3200-3300 feet (976-1007 meters) ; and insolitus, 
3500-5800 feet (1068-1769 meters). Although the data on 
darlingtoni and sheplani are limited, insolitus seems to reach 
higher elevations in the Cordillera Central than any species does 
elsewhere. This may at least in part be due to the fact that no 



18 BREVIORA No. 423 

mountains in Puerto Rico or the Sierra de Baoruco reach such 
high ele\ations as do the mountains within the area known to 
be inhabited by insolitus. 

WilHams and Rand (1969: 9) noted that "It would be a pos- 
sible argument against the close affinity of the two species that 
darlingtoni (72 mm) is approximately twice the snout-vent 
length of insolitus (33 mm). Differences in size between closely 
related species, particularly if they are sympatric, are not un- 
usual, but as far as known, these two species are widely allo- 
patric, and the size difference is extreme." More recently col- 
lected and larger numbers of A. insolitus show that the supposed 
extreme difference in size (= snout-\'ent length) between dar- 
lingtoni and insolitus is not so striking as Williams and Rand 
supposed. In fact, insolitus, which reaches a maximum known 
snout-vent length of 47 mm (not 33 mm) but which is none- 
theless still smaller than darlingtoni, rather bridges the size gap 
between smaller occultus and sheplani and larger darlingtoni. 
The size discrepancy for members of the complex, which Wil- 
Uams and Rand felt might argue against relationships among 
these lizards, is not so striking as they supposed. 

Specimens examined. Anolis occultus: PUERTO RICO, 
20.9 km NNE Guavama, 2300 feet (702 meters) (ASFS 
V4891-92, V4901, V5017-18); 13.7 km N Sabana Grande, 
2800 feet (854 meters) (ASFS V5489-91, V5494) ; 13.7 km 
S Palmer (ASFS V6662-65); 10.6 km SSE Villa Perez, 3400 
feet (1037 meters) (ASFS V6196-97) . 

Anolis insolitus: REPUBLICA DOMINICANA, La Vega 
Province, La Palma, 14 km E El Rio, 3500 feet (1068 meters) 
(ASFS V18739, V18947-19, V22546-53, V31705-10) ; 1.9 mi. 
(3.0 km) SW El Rio, 3900 feet (1190 meters) (ASFS V31656- 
63); 16 km SE Constanza, 5250 feet (1601 meters) (ASFS 
V22502-05); 16.4 km SE Constanza, 5500 feet (1678 meters) 
(ASFS V31614); 18 km SE Constanza, 5800 feet (1769 
meters) (ASFS V19096); 18.5 km SE Constanza, 5800 feet 
(1769 meters) (ASFS V31581-82). Peravia Province, 6.b mi. 
(10.4 km) NW La Horma, 5400 feet (1647 meters) (ASFS 
V31933-37, V31973-74); 8.1 mi. (13.0 km) NW La Horma, 
5800 feet (1769 meters) (ASFS V31927-28). 

Anolis darlingtoni: HAITI, Dcpt. du Sud, Roche Croix, 
Massif de la Hotte, ca. 5000 feet (1525 meters) (MCZ 38251). 



1974 Anolis sheplani 19 

Literature Cited 

Cochran, D. M. 1935. New reptiles and amphibians collected in Haiti by 
P. J. Darlington. Proc. Boston Soc. Nat. Hist., 40 (6) : 367-376. 

Etheridge, R. E. 1960. The relationships of the anoles (Reptilia: Sauria: 
Iguanidae) ; an interpretation based on skeletal morphology. Univ. 
Microfilms, Inc., Ann Arbor, xiii + 236 pp. 11 figs., 10 maps. 

Schwartz, A. 1973. A new species of montane Anolis (Sauria, Iguani- 
dae) from Hispaniola. Ann. Carnegie Mus., 44 (12) : 183-195, 3 figs. 

Thomas, R. 1965. A new anole (Sauria, Iguanidae) from Puerto Rico. 
Part II. Field observations on Anolis occuUus Williams and Rivero. 
Breviora, Mus. Comp. Zool., No. 231: 10-16. 2 figs. 

Webster, T. P. 1969. Ecological observations on Anolis occultus Williams^ 
and Rivero (Sauria, Iguanidae), Breviora, Mus. Comp. Zool., No. 312: 
1-5. 

Williams, E. E., and J. A. Rivero. 1965. A new anole (Sauria, Iguanidae) 
from Puerto Rico. Part I. Description. Breviora, Mus. Comp. Zool., 
No. 231: 1-9, 18. 5 figs. 

, AND A, S. Rand. 1969. Anolis insolitus, a new dwarf anole 

of zoogeographic importance from the mountains of the Dominican 
Republic. Breviora, Mus. Comp, Zool., No. 326: 1-21. 6 figs. 



JUL 8 W74 

B R E V fcvftR A 

Miiseiiin of Comparative Zoology 

us ISSN 0006-9698 

Cambridge, Mass. 28 June 1974 Number 424 

THE LARVA OF SPHINDOCIS DENTICOLLIS FALL 

AND A NEW SUBFAMILY OF GIIDAE 

(GOLEOPTERA: HETEROMERA) 

John F. Lawrence^ 

Abstract. The larva of Sphindocis denticollis Fall is described, and its 
biology is briefly discussed. A new subfamily of Ciidae — the Sphindociinae 
— is proposed for Sphindocis and is formally characterized, while the Ciidae 
and Ciinae are redefined. Speculations are made concerning the phylogenetic 
relationships of the family Ciidae. 

The monotypic genus Sphindocis Fall is based on a very 
interesting fungus-feeding beetle {S. denticollis) that is known 
only from the Transition Zone forests of the northern California 
coast. The genus was originally placed in the family Ciidae 
(Fall, 1917), but it was recently removed from that family and 
tentatively placed in the Tetratomidae (Lawrence, 1971). At 
the suggestion of R. A. Crowson, I made a more detailed study 
of the Sphindocis larva, comparing it and the adult with various 
Ciidae, Tetratomidae, Pterogeniidae, and related Heteromera. 
As as result, I have come to the conclusion that Sphindocis 
represents the closest living relative or sister group of the Ciidae 
and should either be returned to that family or form the basis 
for a new group of equal rank. The former alternative appears 
more reasonable, since the number of families in the Heteromera 
is already excessive. The following treatment includes a descrip- 
tion of the Sphindocis larva, the proposal of a new subfamily 
for the inclusion of this genus, and a recharacterization of the 
family Ciidae and subfamily Ciinae. 

The larval description is based on more than 50 specimens 
collected with adults in the fruiting bodies of Trametes sepium 

^Museum of Comparative Zoology, Cambridge, Mass. 02138. 



2 BREVIORA No. 424 

Berkeley growing on dead branches of madrone {Arbutus Men- 
ziesii) at the following localities in California: Alpine Lake, 
Marin County; 1 mi. N Piercy, 2 mi. N Piercy, 3 mi. S Leggett, 
and 4 mi. W Leggett, Mendocino County. Another eight speci- 
mens were collected without adults in a fruiting body of Poria 
cinerascens (Bresadola) Saccardo and Sydow growing on a 
Douglas fir {Pseudotsuga Menziesii) log at Alpine Lake. A 
single pupa was dug out of madrone wood beneath a fruiting 
body, which may indicate that the beetles require the woody 
substrate for pupation. 

Most of the terms used in the larval description are those 
found in standard works, such as Boving and Craighead (1931) 
and van Emden (1942). For the three labial sclerites, I have 
used the terms prementum, mentum, and submentum, although 
Anderson (1936) has indicated that these are not homologous 
in all groups. Terminology for the ventral thoracic sclerotizations 
follows Watt (1970), while various other terms have been taken 
from Crowson (1955), Glen (1950), Rozen (1958, 1960), St. 
George (1924), and Snodgrass (1935). 

I wish to thank H. B. Leech and the California Academy of 
Sciences, San Francisco, for the loan of specimens; J. T. Doyen 
for collecting adults and larvae of Sphindocis; and R. A. Crow- 
son and E. Mayr for their encouragement. 

DESCRIPTION OF THE MATURE LARVA OF 
Sphindocis denticollis Fall 

Body elongate and subcylindrical, lightly sclerotized except 
for head, anterior part of prothoracic tergum, and pygidium 
(upper part of ninth abdominal tergum). Length about 5 mm; 
width about 0.7 mm. 

Head (Figs. 1-3) exserted, obliquely prognathous, subglob- 
ular, strongly convex dorsally, except for a broad, shallow 
concavity (c) extending from the middle of the epicranial stem 
to the upper part of the frontoclypeal triangle (fc) ; heavily 
sclerotized and yellowish brown in color, with fairly coarse 
and irregular punctation; vestiture consisting of numerous short 
setae and several longer ones, the origins of which are shown 
in Figures 1-3. Epicranial stem (es) about half as long as head 
width; frontal arms (fa) somewhat V-shaped and extending to 
antennal ridges (ar), which conceal antennal insertions; endo- 
carina absent. Frontoclypeal area (fc) bearing two parallel, 
transverse sulci (ts) near epistomal margin (em). Epicranial 



1974 



LARVA OF SPHINDOCIS 







4\^ 





7 






Plate 1 



Figures 1-10. Sphindocis denticollis Fall, larva (1 line = 0.125 mm for 
1-3, 9; 0.063 mm for 4, 7, 8, 10; 0.025 mm for 5, 6) . Fig. 1. Head capsule, 
dorsal view, mandibles and ventral mouthparts removed (dots = setal ori- 
gins) . Fig. 2. Head capsule, ventral view, right mandible and ventral 
mouthparts removed. Fig. 3. Head capsule, lateral view. Fig. 4. Labrum- 
epipharynx, dorsal view. Fig. 5. Epipharynx, median portion. Fig. 6. Left 
antenna, lateral view. Fig. 7. Right mandible, dorsal view. Fig. 8. Left 
mandible, ventral view. Fig, 9. Ventral mouthparts and gular region, ven- 
tral view. Fig. 10. Apex of left maxilla, dorsolateral view. 



4 BREVIORA No. 424 

halves (eh) each bearing a ventral ridge (vr) which extends 
posterad from mandibular articulation, parallel to the hypostomal 
ridge (hr), and forms with the latter a support for the ventral 
mouthparts, which are large and protracted. Ocelli (oc) 5 in 
number, arranged as in Figure 3. Anteclypeus (ac) a short, 
lightly sclerotized band. Labrum (lb) transversely oval, with 
setae and spines as in Figure 4; epipharynx with 4 median 
groups of very short setae or sensillae ( Fig. 5 ) ; tormae ( to ) 
symmetrical, joined posteriorly by a narrow bridge. Antenna 
(Fig. 6) fairly short, less than 1/10 as long as head width, 
3 -segmented, segments about equal in length, II slightly nar- 
rower than I and bearing a sensory appendix (sa) that is longer 
than III and ventral to it, III about half as wide as II and 
bearing a terminal seta almost five times its length; antennal 
insertion separated from the mouth cavity by a narrow bar. 
Gula (gu) not well defined; gular sutures absent and no suture 
between gula and submentum (sm). Posterior tentorial pits (pt) 
and tentorium (tn) as in Figure 2. 

Mandibles (Figs. 7 and 8) symmetrical, large and wedge- 
shaped, with two apical teeth of unequal lengths, an obtuse tooth 
on the cutting edge, and a lightly sclerotized retinaculum (rt) ; 
mola absent; a seta located on the dorsal surface near the middle 
of the lateral edge. Maxillae (Fig. 9) free almost to base of 
mentum; mala (ma) obHquely rounded, its apex armed with 5 
stout spines and several finer setae; inner edge of mala (Fig. 10) 
bearing a dorsal laciniar lobe (la), located at the level of the 
palpifer (pf) and bearing 2 stout apical spines and several long 
setae at base; stipes (st) elongate; cardo (ca) subtriangular ; a 
large, articulating sclerite (as) between stipes and submentum; 
palp 3 -segmented. Labium with a short prementum, a sub- 
quadrate mentum (rne), and a submentum (sm), which is 
raised above the gula but is not separated from it; ligula (li) 
short and rounded, bearing 4 setae at apex; palp 2-segmented. 
Hypopharynx (hy) subquadrate, without a sclerome; hypo- 
pharyngeal bracon (hb) lightly sclerotized except at base of 
hypopharynx. 

Prothorax ( Fig. 1 1 ) slightly longer than meso- or metathorax, 
its tergum (prt) well developed and extending onto lateral sur- 
faces, heavily pigmented anteriorly, becoming very lightly pig- 
mented posteriorly, with a median ecdysial suture; vestiture 
consisting of numerous short setae and 3 transverse rows of 
setae consisting of 12 (anterior edge), 8 (anterior third), and 
10 (posterior third) setae; sternum consisting of a large, tri- 



1974 



LARVA OF SPHINDOCIS 






pap i ^ 



11 





14 





16 




17 




"^'-^ 





Plate 2 

Figures 11-14. Sphindocis denticollis Fall, larva (1 line = 0.063 mm for 
12; 0.250 mm for 11, 13, 14). Fig. 11. Prothorax and mesothorax, ventral 
view, legs removed. Fig. 12. Prothoracic leg, coxa and part of trochanter 
not sTiown. Fig. 13. Apex of abdomen, lateral view. Fig. 14. Apex of 
abdomen, ventral view. Figures 15-21. Sphindocis denticollis Fall, adult 
male (1 line = 0.063 mm for 15, 19; 0.250 mm for 16, 17, 20; 0.125 mm 
for 18, 21) . Fig. 15. Antennal club. Fig. 16. Prothorax, ventral view, right 
coxa removed. Fig. 17. Meso- and metathorax, ventral view, left mesocoxa 
and metacoxae removed. Fig. 18. Metendosternite, dorsal view. Fig. 19. 
Apex of protibia. Fig. 20. Abdomen, ventral view. Fig. 21. Aedeagus, 
ventral view. 



6 BREVIORA No. 424 

angular cervicosternum (cv), a triangular basisternum (bs), and 
vaguely defined sternellum, epistemum, and epimeron; coxal 
cavities (cc) large and obliquely oval, separated by a little less 
than y^ their greatest diameter. Mesothoracic tergum less ex- 
tensive than that of prothorax and lightly pigmented except for 
a transverse carina (tc) at the anterior fifth; several long setae 
scattered on shield; each side w^ith two laterotergites (It), the 
anterior of which bears a biforous spiracle (sp) with the air 
tubes facing dorsad; sternal areas not well defined, coxae slightly 
smaller and broader than those of prothorax. Metathorax simi- 
lar in structure, but with no spiracle on the anterior laterotergite. 
Legs about equal in size, with a large conical coxa, triangular 
trochanter (Fig. 12, tr), the femur (fe) and tibiotarsus (ti) 
about equal in length, and the claw (cl) bearing two setae. 

Abdominal segments 1 to 8 slightly convex dorsally and 
strongly so ventrally; tergal shields lightly pigmented, each with 
an anterior carina and several long setae; each side with a single 
laterotergite (Fig. 13, It), just above which is the spiracle with 
the air tubes facing posterad. Ninth abdominal segment (Figs. 
13 and 14) longer than those preceding it, with a large tergum 
bearing a heavily pigmented, circular, concave, declivous py- 
gidium (py), lined along 34 of its circumference with saw-like 
teeth; ninth sternum reduced in size, bearing at its apex a row 
of anteriorly projecting asperites (asp) ; tenth tergum lunate, 
partly separating ninth tergum and sternum, bearing 3 papillae 
(pap) at its apex; tenth sternum reduced and pygopod-like, 
bearing 5 papillae in front of anal opening (Fig. 14). 

This larva differs from that of any other known ciid in lacking 
an endocarina and having 3-segmented antennae, a maxillary 
articulating sclerite, biforous spiracles, and subanal asperites on 
the ninth sternum. The presence of an endocarina has never 
been noted for the Ciidae, probably because it is directly beneath 
the epicranial stem and does not extend anterad of the frontal 
arms, as it does in various other Heteromera. The epicranial 
stem in Sphindocis is an ecdysial line, whereas in other Ciidae 
it coincides with an internal ridge. The reduced antennal seg- 
mentation in most ciid larvae represents a fusion of the last two 
segments. Symmetrical mandibles also occur in other Ciidae, but 
asymmetry appears to be the more common condition. Biforous 
spiracles appear to be unique to Sphindocis, but a peculiar type 
of accessory air tube has been obserxed in at least one other ciid 
funpubhshed). The concave pygidium of Sphindocis, which 
occurs in other Ciidae, such as Cis melliei (Coquerel, 1849), 



1974 LARVA OF SPHINDOGIS 7 

in the tenebrionid genus Meracantha (Hyslop, 1915), and in 
\arious other substrate-dwelling beetle larvae, represents a type 
of defensive adaptation, which Wheeler (1928) termed phrag- 
mosis. The fruiting body of Trametes sepium is often resupinate 
with a fairly thin context, and the concave and heavily sclero- 
tized pygidium in Sphindocis serves to block the shallow larval 
tunnel against predators or parasites. 

CHARACTERIZATION OF THE FAMILY CIIDAE 

AND ITS SUBFAMILIES 

CiiDAE Leach 

AV^ith the general characters of the Polyphaga: Cucujoidea. 

Adult. Form variable, usually oval to elongate, convex. Size 
0.5-6.0 mm. Head globular, without neck, often strongly de- 
clined, partly concealed by pronotum, without stridulatory files. 
Eye oval, entire, fairly coarsely facetted. Frontoclypeal area 
with a distinct suture, often raised in males to form a ridge, 
horns, or tubercles. Antennal insertion concealed from above 
by frons. Antenna 8- to 1 1 -segmented, with a 2- or 3-segmented 
club, club segments often with multi-pronged sensillae (absent 
in Sphindocis). Mandible bidentate, with a simple cutting edge 
and a quadrangular mola without ridges or tubercles. Maxilla 
with an articulated lacinia and 2-segmented galea {Sphindocis) 
or a fixed lacinia and 1 -segmented galea (Ciinae), palp 4-seg- 
mented, the terminal segment not securiform. Labium with 
ligula reduced, palp 3-segmented. Pronotum margined laterally 
and posteriorly, anterior edge usually produced forward, some- 
times bearing horns in male. Prosternum variable, long or short, 
concave to carinate, coxae globose or transverse, sometimes pro- 
jecting, contiguous to broadly separated, without internalized 
lateral extensions, trochantin usually concealed; procoxal cavities 
open internally, narrowly open or closed externally (posteriorly). 
Elytra not striate, humeri tuberculate, epipleura very narrow, 
extending almost to apex. Scutellum small and subtriangular, 
sometimes absent. Wing venation often reduced, subcubital fleck 
present, anal region with four veins {Sphindocis) or only one 
(Ciinae). Mesosternum transverse, sometimes extremely re- 
duced, coxae globose and narrowly separated, coxal cavities not 
closed outwardly by sterna, trochantins exposed or not. Meta- 
sternum subquadrate, with or without median suture, without 
coxal lines, coxae narrow, transverse, subcontiguous. Metendo- 
sternite with a long median stalk {Sphindocis) or none (Ciinae), 



8 BREVIORA No. 424 

anterior tendons arising near the apices of the lateral arms. 
Tarsal formula in both sexes 4-4-4 (occasionally 3—3—3), tarsi 
simple, the first three segments small and subequal, terminal 
segment elongate, claws simple. Trochanters oblique, completely 
(Ciinae) or only partly {Sphindocis) separating coxa from 
femur. Tibial spurs usually absent; 2 reduced spurs in Sphin- 
docis. Outer edge of protibia often expanded and modified at 
apex. Abdomen with 5 visible stemites, the first 2 (III and IV) 
connate {Sphindocis) or not (Ciinae). First visible sternite 
(III) without coxal lines, often with a median pubescent fovea 
in male. Aedeagus of inverted heteromeroid type, with ventral 
tegmen and dorsal median lobe. 

Larva. Body elongate and subcylindrical, lightly sclerotized, 
except at anterior and posterior ends. Head subglobular, ob- 
liquely prognathous, with well-developed epicranial stem and 
Y-shaped frontal arms, endocarina present (Ciinae) or not 
[Sphindocis) ; ventral epicranial ridge present behind mandib- 
ular articulation. Ocelli usually 5, occasionally fewer or none. 
Antennal insertion concealed from above and separated from 
mouth cavity by a narrow bar. Antenna short, 2- or 3 -seg- 
mented, with a long sensory appendix on segment II and a very 
long terminal seta. Gular area short, sutures present or absent. 
Mandibles large and wedge-shaped, usually somewhat asym- 
metrical, with 2 apical teeth, a simple cutting edge, often with 
a lightly sclerotized retinaculum, mola usually absent. Maxilla 
free at least to middle of mentum, with a narrow articulating 
membrane (Ciinae) or a large articulating sclerite {Sphindocis) 
between stipes and submentum; mala obliquely rounded, inner 
edge with a dorsal laciniar lobe; palp 3-segmented. Labium with 
short prementum, subquadrate mentum, and elongate submen- 
tum, the last separated from gula by suture or not; ligula short 
and rounded, with 2 or 4 setae; palp 2-segmented. Hypo- 
pharynx without sclerome. Thoracic terga well developed and 
extending onto sides; prothorax slightly larger than meso- or 
metathorax; prosternum with a large triangular cervicoster- 
num; procoxae large and fairly close together; spiracle annular 
(Ciinae) or biforous {Sphindocis), located on anterior latero- 
tergite of mesothorax. Legs fairly short and broad, subequal; 
claw with 2 setae. Abdominal spiracles located above latero- 
tergites. Ninth tergum variously modified, usually heavily sclero- 
tized and with urogomphi; tenth sternum reduced and pygopod- 
like; anal opening surrounded by several papillae. 



1974 LARVA OF SPHINDOCIS 9 

Sphindociinae, New Subfamily 

Adult. Antenna 11 -segmented, with 3 -segmented club (Fig. 
15); club segments without multi-pronged sensillae. Maxilla 
with an articulated lacinia and a 2-segmented galea. Pronotum 
(Fig. 16) with lateral margins broadly crenulate, so that several 
round teeth are formed; procoxal cavities with a slight lateral 
extension, which may expose part of trochantin. Mesocoxal 
cavities ( Fig. 1 7 ) with exposed trochantins ( t ) . Metendosternite 
(Fig. 18) with a long stalk (s), a narrow lamina (1), and the 
anterior tendons (at) near the apices of lateral arms. Hindwing 
with well-developed anal region, bearing 4 veins and a wedge 
cell. Trochanter (Fig. 17, tr) of heteromeroid type, obliquely 
joined to femur so that the latter is in direct contact with coxa 
at one point. Tibial apices (Fig. 19) simple, with 2 reduced 
spurs. Abdominal sternites III and IV connate (Fig. 20), III 
with a median pubescent fovea in male. Aedeagus (Fig. 21) 
with a large basal piece (bp), with two apical condyles (cd), 
a well-sclerotized ventral paramere (pm) with 2 pairs of setae 
near its base, and a membranous median lobe with 2 lateral 
struts (Is). 

Larva. Head without endocarina, with 5 ocelli. Antenna 3- 
segmented. Mandibles symmetrical, without mola and with 
lightly sclerotized retinaculum. Maxilla free almost to base of 
mentum, with a large articulating sclerite between stipes and 
submentum. Spiracle biforous. Ninth tergum bearing a concave 
pygidium surrounded by saw-like teeth; ninth sternum bearing 
a row of asperites. 

CiiNAE Leach 

Adult. Antenna 8- to 10-segmented, with a 2- or 3 -segmented 
club; club segments with at least 4 multi-pronged sensillae. 
Maxilla with a reduced and fixed lacinia and a 1 -segmented 
galea. Pronotum with lateral margins never broadly crenulate 
or. toothed; procoxal cavities without lateral extension, trochan- 
tin always concealed. Mesocoxal cavities with trochantins con- 
cealed. Metendosternite with median stalk very short and 
broad, so that arms may appear to arise independently. Hind- 
wing with reduced anal region bearing a single vein. Trochanter 
of normal type, oblique but completely separating coxa and 
femur. Tibial spurs absent on all legs, apices of tibiae, especially 
protibiae, variously expanded and modified. Abdominal sternites 
free, III often with a median pubescent fovea in male. Aedeagus 



10 BREVIORA No. 424 

with a small basal piece, without condyles, paramere variously 
modified at apex but without basal setae, and median lobe 
sclerotized and without lateral struts. 

Larva. Head with endocarina, ocelli 5 or less. Antenna 2- 
segmented. Mandibles often asymmetrical, with or without mola 
and retinaculum. Maxillae free to about middle of mentum, 
without an articulating sclerite at its base. Spiracles annular. 
Ninth tergum variously modified, usually with two urogomphi; 
ninth sternum without asperites. 

This subfamily includes all members of the family except 
Sphindocis. 

DISCUSSION 

The major justification for uniting Sphindocis and the Ciidae 
is the joint possession by the two groups of at least one feature — 
the distinctive laciniar lobe of the larval maxilla — which is 
certainly unique and derived. This particular type of structure is 
found in no other cucujoid beetle, and it is sufficiently complex 
and similar in the two groups to make convergence unlikely. 
There is no reason to believe that the cleft malar apex of the 
Zopheridae, Cephaloidae, and Synchroidae, or the various teeth, 
spines, or hooks (to which the word uncus is often appHed) of 
Anaspis, the Oedemeridae, and various other Heteromera are 
homologous to this laciniar lobe. The loss of the mandibular 
mola and of the hypopharyngeal sclerome in the larva are also 
derived features, but it would be difficult to demonstrate their 
uniqueness. The lightly sclerotized and tooth-like "retinaculum" 
of the larval mandible appears to be unique in the Heteromera, 
but similar structures occur in a number of Clavicornia, sug- 
gesting that the character may be primitive. In the adult stage, 
the reduction of the ligula and the presence of an abdominal 
fovea in the male may both represent synapomophic conditions, 
but most other adult characters are shared by one or more 
Heteromera. The abdominal fovea is rare in this section of the 
Cucujoidea, although some Mycteridae and at least one myceto- 
phagid have abdominal tufts or patches of hairs in the male. 
Foveae similar to those of ciids, however, do occur in certain 
Erotylidae among the Clavicornia (Delkeskamp, 1959). 

The erection of a new subfamily for Sphindocis is based on 
numerous differences between this genus and all of the remaining 
ciids. In larval Ciinae, the antennae are reduced to two seg- 
ments, an endocarina is present, the maxillary articulating area 



1974 LARVA OF SPHINDOCIS 11 

is reduced to a narrow membrane, the spiracles are annular 
without a pair of contiguous air tubes, the ninth sternite lacks a 
row of asperites, and the gula and submentum are not fused, 
while in the adults of this subfamily, the antennae always have 
less than 1 1 segments, the club segments bear multi-pronged 
sensillae, the galea has only a single segment, the lacinia is not 
articulated, the anal region of the hindwing has only a single 
vein, the pro- and mesotrochantins are concealed, the trochanters 
are not heteromeroid, the tibial spurs are lacking, the abdominal 
stemites are free, and the median lobe of the aedeagus is sclero- 
tized. Most of these characters are derived and several are ob- 
viously associated with reduction in size (hindwing, antennal 
segments of adult and larva, adult maxilla ) . The development 
of large and complex hygroreceptor sensillae on the antennal 
club probably represents an improvement in the ability to locate 
fungus sporophores, while the formation of a larval endocarina, 
reduction of the maxillary articulating area, the further enclosure 
of the pro- and mesocoxae, and the loss of tibial spurs may have 
been associated with the utilization of a tougher fungus substrate. 

The relationships of the Ciidae to other heteromerous families 
are still somewhat obscure, and a detailed discussion must await 
a study now in progress on adult and larval Heteromera. Crow- 
son (1966) suggested that the Ciidae, along with the Pteroge- 
niidae, Tetratomidae, and Mycetophagidae, might be direct off- 
shoots from a biphyllid-byturid type of heteromeran ancestor, 
and that the Pterogeniidae might represent the sister group of 
the Ciidae. I have agreed basically with Crowson's views ( Law- 
rence, 1971), while allowing for the possibility that the ciids 
have evolved directly from a clavicorn ancestor, perhaps related 
to Cryptophilus or Setariola in the Languriidae. 

The Pterogeniidae resemble ciids both as adults and larvae, 
but the similarities may be due to the fact that both groups 
inhabit the woodier fungi. Adult pterogeniids differ from the 
Ciidae in having filiform antennae, securiform maxillary palps, 
a '5-5-4 tarsal formula, internally closed procoxal cavities, and 
distinct lateral lobes on the aedeagus. The larvae of Pterogenius 
and Histanocerus, which are being described elsewhere, differ 
from those of ciids in having a characteristically curved epi- 
cranial stem, an extensive mandibular mola with transverse 
ridges, a well-developed and molar-like hypopharyngeal sclerome, 
and no laciniar lobe on the maxilla. 

The row of asperites at the apex of the ninth sternite in the 
Sphindocis larva is found outside the group only in the genus 



12 BREVIORA No. 424 

Prostomis, which has been placed in a separate family of un- 
certain affinities. The row of asperites in the larvae of Pythidae, 
Pyrochroidae, and Othniidae is always at the base of the ninth 
sternite and is apparently not homologous to that of Sphindocis. 
The Prostomidae differ from ciids in having closed front and 
middle coxal cavities in the adult and a simple mala, well- 
developed mola, and hypopharyngeal sclerome in the larva. 

The Tetratomidae have also been considered as a possible 
sister group of the Ciidae, and certain characters of both adult 
and lars^a tend to support this hypothesis. Adults of the Tetra- 
tomidae (excluding Mycetoma, removed by Crowson, 1966, and 
Viedma, 1966) and the related Mycetophagidae are similar to 
ciids in having internally and externally open procoxal and 
laterally open mesocoxal cavities, while the pisenine tetratomid 
Eupisenus elongatus (LeConte) bears a striking superficial re- 
semblance to Sphindocis. The procoxal cavity in all tetratomids 
has a distinct lateral extension that exposes the trochantin; in 
Sphindocis there is a slight extension of the cavity, while in the 
Ciinae it is absent. The hindwing of Sphindocis is similar to 
that of tetratomids in having a wedge cell and subcubital fleck 
and differs in having four rather than five anal veins, while the 
metendosternite is essentially of the tetratomid type with a re- 
duced lamina. In the Ciinae, both the hindwing and the meten- 
dosternite have undergone extreme reduction and modification. 

The male genitalia of the Tetratomidae are variable, and 
Miyatake (1960) has described and illustrated two major types: 
that of Pisenus, with the basal piece ventral and bearing two 
ventral accessory lobes in addition to the parameres, which are 
free; and that of the Tetratomini, with the basal piece dorsal 
and bearing only parameres, which are at least partly fused 
together. In the genus Pent he (Penthini) the genitalia are of 
the tetratomine type, but in Eupisenus, a distinctive type occurs 
with the basal piece ventral and the parameres fused into a 
single piece notched at the apex; moreover, this single paramere 
bears near the base two clusters of six or seven setae, which are 
in the same positions as the two pairs of setae in Sphindocis. 
The median lobe is also like that of Sphindocis in being mem- 
branous with lateral struts that meet at the apex. 

The larv^ae of Tetratomidae are also quite variable, but they 
differ consistently from those of Ciidae in having lyre -shaped 
frontal arms and no laciniar lobe on the maxilla. The mandible 
of Pisenus resembles that of the Mycetophagidae in having a 
mola with transverse ridges grading into tubercles or asperites on 



1974 LARVA OF SPHINDOCIS 13 

the ventral surface (Hayashi, 1971; 1972). In Eupisenus, the 
niola is simple and concave and is bordered by two rows of teeth 
that grade into tubercles both dorsally and ventrally. In the 
Tetratomini (Crowson, 1964) the mola is further reduced with 
only three or four teeth, while in Pent he there is no mola. The 
hypopharyngeal sclerome, which can often be correlated with 
molar development, is well developed and tooth-like in Pisenus, 
consists of a transverse band in Eupisenus and the tetratomines, 
and is barely sclerotized in Penthe. It would not be difficult to 
derive the simple mandible and unsclerotized hypopharynx of 
the Ciidae from a form like Eupisenus, and it is also possible 
that the "retinaculum" of the Ciidae represents a remnant of 
the molar teeth in tetratomids, rather than a carry-over of the 
clavicorn retinaculum. 

LITERATURE CITED 

Anderson, W. H. 1936. A comparative study of the labium of coleopter- 
ous larvae. Smiths. Misc. Coll., 95 (13) : 1-29. 

BoviNG, A. G., AND F. C. Craighead. 1931. An illustrated synopsis of the 
principal larval forms of the Coleoptera. Ent. Amer. (N.S.) , 11: 1-351, 
125 pis. 

CoQUEREL, C. 1849. Observations entomologiques sur divers Coleopteres 
recueillis aux Antilles. Ann. Soc. Ent. France, ser. 2, 7: 441-454, pi. 14. 

Crowson, R. a. 1955. The Natural Classification of the Families of Cole- 
optera. London: Lloyd. 187 pp. 

. 1964. Observations on British Tetratomidae (Col.) , with 

a key to the larvae. Ent. Mon, Mag., 94: 82-86. 

. 1966. Observations on the constitution and subfamilies of 



the family Melandryidae. Eos, 41: 507-513. 
Delkeskamp, K. 1959. Sekundare Geschlechtsmerkmale bei Erotyliden. 

Wiss. Zeit. Martin-Luther-Universitat Halle-Wittenberg, Math.-Nat., 

8 (6) : 1089-1098. 
Emden, F. van. 1942. Larvae of British beetles — III. Keys to families. 

Ent. Mon. Mag., 78: 206-226, 253-272. 
Fall, H. C. 1917. New Coleoptera — VI. Canadian Ent., 49: 163-171. 
Glen, R. 1950. Larvae of the elaterid beetles of the tribe Lepturoidini 

(Coleoptera: Elateridae) . Smith. Misc. Coll., 111(11): 1-246. 
Hayashi, N. 1971. On the larvae of Mycetophagidae occurring in Japan 

(Coleoptera: Cucujoidea) . Kontyu, 39: 361-367. 
1972. On the larvae of some species of Colydiidae, Tetratomi- 
dae and Aderidae occurring in Japan (Coleoptera: Cucujoidea) . Kontyu, 

40: 100-111. 
Hyslop, J. A. 1915. Observations on the life history of Meracantha con- 

tracta (Beauv.) . Psyche, 22: 44-48, pi. 4. 



14 BREVIORA No. 424 

Lawrence, J. F. 1971. Revision of the North American Ciidae (Coleop- 

tera) . Bull. Mus. Comp. Zool., 142: 419-522. 
MiYATAKE, M. 1960. The genus Pisenus Casey and some notes on the 

family Tetratomidae (Coleoptera) . Trans. Shikoku Ent. Soc, 6: 121-135. 
RozEN, J. G. 1958. The external anatomy of the larva of Nacerdes mela- 

nura (Linnaeus) (Coleoptera: Oedemeridae) . Ann. Ent. Soc. America, 

51: 222-229. 

1960. Phylogenetic-systematic study of larval Oedemeridae 

(Coleoptera) . Misc. Publ. Ent, Soc. America, 1 (2) : 35-68. 
St. George, R. A. 1924. Studies on the larvae of North American beetles 

of the subfamily Tenebrioninae with a description of the larva and 

pupa of Merinus laevis (Olivier) . Proc. U. S. Nat. Mus., 65 (1) : 1-22, 

pis. 1-4. 
Snodgrass, R. E. 1935. Principles of Insect Morphology. New York: Mc- 
Graw-Hill. X + 667 pp. 
ViEDMA, M. G. de. 1966. Contribucion al conocimiento de las larvas de 

Melandryidae de Europa (Coleoptera) . Eos, 41: 483-506. 
Watt, J. C, 1970. Coleoptera: Perimylopidae of South Georgia. Pacific 

Ins. Mon., 23: 243-253. 
Wheeler, W. M. 1928. The Social Insects. Their Origin and Evolution. 

New York: Harcourt-Brace. xviii + 378 pp. 



JUL 8 1P74 



B R E V^T-O^ R A 

Miisenni of Comparative Zoology 



us ISSN 0006-9698 



Cambridge, Mass. 28 June 1974 Number 425 

SYSTEMATIGS AND DISTRIBUTION OF 

GERATIOID ANGLERFISHES OF THE GENUS 

LOPHODOLOS (FAMILY ONEIRODIDAE) 

Theodore W. Pietsch^ 

Abstract. The genus Lophodolos of the family Oneirodidae is reviewed 
on the basis of all known material. Two species are recognized, L. acantho- 
gnatlius Regan and L. indicus Lloyd. Lophodolos dinema Regan and Tre- 
wavas is considered a junior synonym of L. indicus Lloyd. The tentative 
distribution of each species is plotted and a key to the species of the genus 
is provided. 

INTRODUCTION 

The genus Lophodolos was erected by Lloyd (1909a) to in- 
clude a single species, L. indicus, on the basis of a specimen 
collected from the Indian Ocean by the Royal Indian Museum 
Survey Ship Investigator. Since that time three additional 
species have been described: L. acantho gnathus Regan (1925), 
to which have been referred more than 60 specimens from the 
Atlantic and western Pacific oceans; L. lyra Beebe (1932), 
synonymized with L. acantho gnathus by Regan and Trewavas 
(1932); and L. dinema Regan and Trewavas (1932), repre- 
sented by a single specimen from the South China Sea. 

The number of female specimens of Lophodolos has doubled 
since the appearance of Bertelsen's ( 1 95 1 ) monograph on the 
Ceratioidei. In spite of extensive information gained from this 
increase in material, taxonomic study of the genus is by no means 
complete. Metamorphosed males are unknown; thus, species 
are based only on females. The separation of species is based 
on only a few characters, the most important being the morphol- 
ogy of the esca and the length of the illicium. Differences in 

^Museum of Comparative Zoology, Cambridge, Massachusetts 02138 



2 BREVIORA No. 425 

these two characters merge in specimens less than 25 mm stand- 
ard length, making differentiation particularly difficult. Never- 
theless, the material presently known appears to represent only 
two forms: L. acanthognathus Regan (1925) and L. indicus 
Lloyd (1909a). 

METHODS AND MATERIALS 

Standard lengths (SL) were used throughout. Measurements 
were taken on the left side of the fish whenever possible and 
rounded to the nearest 0.5 mm in specimens greater than 20 mm, 
and to the nearest 0.1 mm in specimens less than 20 mm. To 
insure accurate fin-ray counts, skin was removed from the pec- 
toral fins and incisions were made to reveal the rays of the dorsal 
and anal fins. lUicium length is the distance from the articula- 
tion of the pterygiophore of the illicium and the illicial bone to 
the dorsal surface of the escal bulb, excluding escal appendages. 
Terminology used in describing the various parts of the angling 
apparatus follows that of Bradbury (1967). Definitions of terms 
used for the different stages of development follow those of 
Bertelsen (1951: 10-11). "^ 

Locality data is given for primary type material only. Com- 
plete locality data for all specimens examined may be obtained 
by writing to the author. 

The generic diagnosis (much of which is taken from osteologi- 
cal evidence presented elsewhere: Pietsch, 1974) and descrip- 
tion are based on 98 metamorphosed females ranging from 6.0 
to 77.0 mm (metamorphosed males are unknown). Larvae were 
described by Bertelsen ( 1 95 1 : 1 06 ) . Study material is deposited 
in the following institutions : 

BMNH British Museum (Natural History), London. 
BOC Bingham Oceanographic Collections, Peabody Mu- 

seum of Natural History, Yale University. 
BZM University of Bergen Zoological Museum. 

CAS California Academy of Sciences, San Francisco. 

FMNH Field Museum of Natural History, Chicago. 
GNM Natural History^ Museum of Goteborg. 
IMC Indian Museum, Calcutta. 

ISH Institut fiir Seefischerei. 

LACM Los Angeles County Museum of Natural History. 
MCZ Museum of Comparative Zoology, Harvard University. 

NIO National Institute of Oceanography, Surrey, England. 

NYZS New York Zoological Society. 



1974 ANGLERFISHES OF THE GENUS LOPHODOLOS 3 

ROM Roval Ontario Museum. 

SIO Scripps Institution of Oceanography, La Jolla. 

SU Stanford University (collections now housed at the 

California Academy of Sciences, San Francisco). 

UMML University of Miami Marine Laboratory. 

USNM United States National Museum, Washington. 

ZMUC Zoological Museum, University of Copenhagen. 

ACKNOWLEDGEMENTS 

I thank Erik Bertelsen and Karel F. Liem for critically read- 
ing the manuscript and offering valuable suggestions. Thanks 
are also due the following persons and their institutions for mak- 
ing material available : Robert J. Lavenberg and Jerry Neumann 
(LACM); Erik Bertelsen and j0rgen Nielsen (ZMUC); Ger- 
hard Krefft (ISH); Richard H. Rosenblatt (SIO); W. B. 
Scott (ROM) ; William N. Eschmeyer and Tomio Iwamoto 
(CAS); Alwyne Wheeler (BMNH) ; C. Richard Robins 
(UMML) ; Nigel Merrett and JuHan Badcock (NIO) ; Robert 
H. Gibbs, Jr. (USNM); Robert K. Johnson (FMNH) ; 
Thomas A. Clarke, Hawaii Institute of Marine Science, Uni- 
versity of Hawaii; and MicheL Legand, Office de la Recherche 
Scientifique et Technique Outre-Mer, Noumea, New Caledonia. 
A. G. K. Menon of the Zoological Survey of India, Calcutta, 
kindly provided information and a sketch of the esca of the 
holotype of Lophodolos indicus. Finally, I thank Patricia Chaud- 
huri for the fine illustrations. 

SYSTEMATICS 
Genus Lophodolos Lloyd, 1909a 

Lophodolos Lloyd, 1909a: 167 (type species Lophodolos indicus Lloyd, 1909a, 
by original designation and monotypy) . Fowler, 1936: 1337, 1339-1340, 
1365, fig. 560 (brief description after Regan, 1926; in key) . Pietsch, 
1974: in press (osteology; relationships) . 

Lophodolus (emended or erroneous spelling of Lophodolos by various 
authors) . 

Oneirodes Murray and Hjort, 1912: 104, fig. 90 (in part; erroneous designa- 
tion; type species Oneirodes eschrichtii Liitken, 1871, by original desig- 
nation and monotypy) . 

Lophodulus (erroneous spelling of Lophodolos by various authors) . 

Diagnosis. The genus Lophodolos is distinguished from all 
other genera of the family Oneirodidae by the following charac- 
ters : dorsal profile of frontal bones concave ; ventromedial exten- 



% BREVIORA No. 425 

sions of frontals absent; posterior end of frontal in contact with 
respective prootic; pterosphenoid absent; pterygiophore of illi- 
cium emerging between or behind sphenotic spines; symphysial 
and sphenotic spines extremely well developed; medial ends of 
hypobranchials II (as well as hypobranchials III) approaching 
each other on the midline (see Pietsch, 1974: in press). 

In addition, Lophodolos is unique in having the following 
combination of characters: snout short, mouth large, cleft ex- 
tending past eye; vomerine teeth absent; anterior end of pterygio- 
phore of illicium exposed, its posterior end concealed under skin ; 
articular spines present, quadrate spine larger than mandibular 
spine; angular spine present; pharyngobranchials I and II ab- 
sent; pectoral lobe short and broad, shorter than longest rays of 
pectoral fin ; operculum bifurcate ; suboperculum slender through- 
out length, its upper end tapering to a point, its lower end 
rounded, with a small anterior projection in some adolescent 
specimens; skin naked, covering caudal fin to some distance from 
fin base. 

Description. Body relatively long, slender, not globular; jaws 
equal anteriorly; lower jaw with an unusually long symphysial 
spine; oral valves well developed, lining inside of both upper 
and lower jaws; two nostrils on each side at end of a single short 
tube; labial cartilage well developed (Pietsch, 1972a: 31); 
angular bone terminating as a well-developed spine; eye sub- 
cutaneous, appearing through a circular, translucent area of 
integument; gill opening oval in shape, situated just postero- 
ventrad to pectoral lobe; skin naked (embedded dermal spines 
cannot be detected microscopically in cleared and stained speci- 
mens) ; lateral line papillae as described for other oneirodids 
(Pietsch, 1969, 1972b) ; ovaries paired; pyloric caeca absent. 

Illicium length 11. 1 to 138.0 percent of SL, becoming longer 
proportionately with growth ( Fig. 1 ) ; anterior end of pterygio- 
phore of illicium exposed, emerging on head between or behind 
sphenotic spines, its posterior end concealed under skin; esca 
with a pair of unpigmented, bilaterally placed appendages arising 
from distal surface. 

Teeth slender, straight, all depressible, and weakly set (easily 
damaged or lost), in overlapping sets as described for other 
oneirodids (Pietsch, 1972b: 5, fig. 2) ; teeth in lower jaw larger 
and more numerous than those in upper jaw; number of teeth 
in lower jaw 200 to 280 (based on five specimens, 57.0- 
77.0 mm) ; pharyngobranchial II absent; pharyngobranchial III 
well developed and bearing numerous teeth. 



1974 ANGLERFISHES OF THE GENUS LOPHODOLOS 



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Figure 1. Relationship of illicial length and standard length for species 
of Lophodolos. 



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Figure 2. Relationship of escal bulb width and standard length for 
species of Lophodolos. 



BREVIORA 



No. 425 



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1974 ANGLERFISHES OF THE GENUS LOPHODOLOS 7 

Color in presentation dark brown to black over entire external 
surface of body except for bulb and appendages of esca (escal 
appendages and unpigmented distal portion of escal bulb silvery- 
white in unpreserved specimens of L. acanthognathus; E. Bertel- 
sen, personal communication) ; oral cavity and guts except for 
outer surface of stomach wall unpigmented. 

D. 5-8, first ray of dorsal fin reduced to a small stub; A. 
4-7; P. 17-21 (Table 1); pelvics absent; C. 9 (2 unbranched 
- 4 branched - 3 unbranched ) ; branchiostegal rays 6 ( 2 + 4 ) . 

Relationships. Lophodolos appears to be the most derived 
genus of the thirteen oneirodid genera. It is extremely special- 
ized in many ways and, although probably derived from a 
Microlophichthys-likt ancestor (a relatively primitive member 
of the family ) , it shows little resemblance to any other oneirodid 
(seePietsch, 1974). 

Distribution. Both species of Lophodolos have a wide hori- 
zontal distribution, and occur in all three major oceans of the 
world. Lophodolos indicus has not been taken in the western 
Atlantic where 82 percent of the material of L. acanthognathus 
has been collected. On the other hand, L. acanthognathus is rep- 
resented in the eastern Pacific by only three specimens ( Fig. 9 ) . 

Since virtually all collections of Lophodolos were made with 
nonclosing nets, vertical distributions are based on the maximum 
depths reached by fishing gear for each capture. Metamor- 
phosed specimens were taken between approximately 650 m 
and an unknown lower limit. All specimens larger than 30 mm 
(37 individuals) were captured by nets fished below 1000 m; 
62 percent of these were captured by nets fished below 1500 m. 
Material of both species from any one geographical area was 
insufficient to show whether there is any vertical separation be- 
tween the two forms. 

Comments. The original spelling of the generic name Lopho- 
dolos (Lloyd, 1909a), is reestablished as the "correct original 
spelling," as provided by Article 32(a) of the International Code 
of Zoological Nomenclature. 

Key to the Females of the Species of the Genus Lophodolos 

lA. Length of illicium less than 25 percent of SL in specimens 30 mm and 
larger (Fig. 1) ; width of escal bulb 4.4-6.7 percent of SL in specimens 
25 mm and larger (Fig. 2) ; length of escal appendages 10.2-20.9 percent 
of SL in specimens 25 mm and larger, 8.7-22.2 (usually greater than 
10.0) percent of SL in specimens less than 25 mm (Figs. 3-4) ; length of 
sphenotic spine 4.1-9.2 (usually greater than 6.0) percent of SL in 
specimens 30 mm and larger (Fig. 5) ; length of quadrate spine 2.9-6.5 



8 BREVIORA No. 425 

(usually greater than 3.5) percent of SL in specimens 30 mm and larger 
(Fig. 6) ; D. 5-7 (Table 1) L. acanthognathus Regan, 1925. 

IB. Length of illicium greater than 25 percent of SL in specimens 30 mm 
and larger (Fig. 1) ; width of escal bulb 2.1-4.0 percent of SL in speci- 
mens 25 mm and larger (Fig. 2) ; length of escal appendages 1.2-5.0 
percent of SL in specimens 25 mm and larger, 4.2-10.5 (usually less 
than 9.0) percent of SL in specimens less than 25 mm (Figs. 3-4) ; 
length of sphenotic spine 1.9-6.0 (usually less than 5.0) percent of SL 
in specimens 30 mm and larger (Fig. 5) ; length of quadrate spine 
1.6-5.0 (usually less than 3.0) percent of SL in specimens 30 mm and 
larger (Fig. 6) ; D. 6-8 (Table 1) L. indicus Lloyd, 1909a. 

Lophodolos acanthognathus Regan, 1925 

Figure 3 

Oneirodes n. sp. Murray and Hjort, 1912: 104, fig. 90 (erroneous designation; 
specimen referred to L. acanthognathus by Nybelin, 1948) . 

Lophodolus acanthognathus Regan, 1925: 563 (original description; two 
specimens; lectotype designated by Bertelsen, 1951, ZMUG P92104, 
12.0 mm; DANA Station 1358 (5), western North Atlantic, 28°15'N, 
56°00'W; 3000 m wire; 1530 hr; 2 June 1922) . Regan, 1926: 30, pi. 6, 
fig. 1 (brief description; one additional specimen) . Regan and Tre- 
wavas, 1932: 83 (description after Regan, 1926; five additional speci- 
mens; L. lyra Beebe, 1932, a synonym of L. acanthognathus) . Gregory, 
1933: 402, 404, figs. 274, 276A, 277 (osteological comments; specific name 
misspelled acanthagnathus in fig. 277) . Beebe, 1937: 207 (45 specimens 
listed from Bermuda) . NybeUn, 1948: 86-89, Text-fig. 9, table 20 
{Oneirodes n. sp. of Murray and Hjort, 1912, referred to L. acanthog- 
nathus; description of an additional specimen; comparison with previous 
descriptions; geographic, bathymetric distribution) . Bertelsen, 1951: 
107, figs. 64-65, tables 21-22 (synonymy; description; comparison with 
all known material; DANA material listed; comments; in key) . Grey, 
1955: 299 (one additional specimen) . Grey, 1956: 255 (synonymy; 
vertical distribution) . 

Lophodolus lyra Beebe, 1932: 96-98, fig. 28 (original description; about 40 
specimens; holotype, USNM 170949, 47.0 mm; GLADISFEN Net 111, 
32°12'N, 64°36'W; 1463 m; 27 July 1931). Koefoed, 1944: 7, pi. 3, 
fig. 3 (misidentifications; description; three specimens including Onei- 
rodes n. sp. of Murray and Hjort, 1912) . 

Lophodolos acanthognathus, Fowler, 1936: 1340, 1365, fig. 560 (corrected 
spelling; brief description after Regan, 1926) . Pietsch, 1972a: 35, 45 
(osteological comments) . Pietsch, 1974: in press (osteology; relation- 
ships) . 

Material. Seventy-six female specimens, 6.0-70.0 mm: 
BMNH 4(18.0-26.0 mm); BOC 3; BZM 3(8.5-51.0 mm); 
FMNH 1(9.5 mm); GNM 1(56.0 mm); ISH 6(46.0-70.0 



1974 



ANGLERFISHES OF THE GENUS LOPHODOLOS 




Figure 3. Esca of Lophodolos acanthognathus, LACM 10011-9, 38.0 mm, 
left lateral view. Drawn by Patricia Chaudhuri. 



10 BREVIORA No. 425 



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Standard Length m mm 

Figure 4. Relationship of escal appendage length and standard length 
for species of Lophodolos. 



mm); LACM 4(22.5-38.0 mm); MCZ 2(18.0-65.0 mm): 
ROM 13(17.0-57.0 mm); SU 32(6.0-32.0 mm); USNM 
2(10.0-47.0 mm); ZMUC 5(8.5-40.0 mm). 
Diagnosis. See key to species. 

Description. Illicium short, 11.1-23.1 (Fig. 1); width of 
escal bulb large, 4.2-9.0 (Fig. 2); escal appendages long, 8.7- 
22.2 (Figs. 3-4); sphenotic spines long, 4.1-9.2 (Fig. 5); 
quadrate spines long, 2.9-6.5 (Fig. 6) ; D. 5-7 (only one speci- 
men had D. 7, ISH 500/73); A. 4-6; P. 17-21 (Table 1) 
(measurements in percent of SL; spine lengths based on speci- 
mens greater than 30 mm, fin ray counts on specimens greater 
than 20 mm). 

Rest of characters as for genus. 

Distribution. Lophodolos acanthognathus is known from 
both sides of the Atlantic. The vast majority of specimens (82 
percent, including all type material) have been collected from 
the western half of this ocean as far east as 26°W, between 58°N 
and 25 °N. In the eastern Atlantic the range extends from ap- 
proximately 48°N, 18°W, southward, off the southern tip of 



1974 



ANGLERFISHES OF THE GENUS LOPHODOLOS 



11 



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species of Lophodolos. 



Portugal and the continental slope of Africa to2°S, 26°W. A 
single record is known from the central South Atlantic at ap- 
proximately 40°S, 26°W. 

In the Indo-Pacific region L. acanthognathus is represented 
by three specimens: one from the Bay of Bengal, Indian Ocean 
(at approximately 7°N, 60°E), and two from the South China 
and Celebes seas. Three records are known from eastern Pacific 
Equatorial waters: on the equator at 139°W and from off the 
coast of Peru. The lectotype was collected from the western 
north Adantic at 28°15'N, 56°00'W (Fig. 9). 

On the basis of maximum depths reached by fishing gear, 
metamorphosed L. acanthognathus are vertically distributed be- 
tween approximately 650 m and an unknown lower limit. All 



12 BREVIORA No. 425 



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Standard Length in mm 

Figure 6. Relationship of quadrate spine length and standard length for 
species of Lophodolos. 



specimens larger than 30 mm (19 individuals) were captured 
by nets fished below 1000 m; 58 percent of these were captured 
by nets fished below 1500 m. 

Comments. Specimens of L. acanthognathus larger than ap- 
proximately 30 mm can easily be separated from L. indicus on 
the basis of illicial and escal appendage lengths alone (see key to 
species). Smaller specimens, especially those less than 20 mm, 
are difficult to identify, and require a combination of meristics 
and counts, all of which overlap between the two species: 
illicial and escal appendage lengths, width of escal bulb, and 
dorsal fin ray counts (See Figs. 1-2, 4, Table 1). In some 
cases, geographic distribution may provide additional data for 
identification; L. indicus apparently does not occur in the western 
North Atlantic where approximately 82 percent (62 indi\iduals) 
of the known material of L. acanthognathus has been collected 
(Fig. 9). 

The holotype L. lyra Beebe (1932) compares well with the 
known material of L. acanthognathus ; the name is retained as a 
synonym of L. acanthognathus following Regan and Trewavas 

(1932). 



1974 ANGLERFISHES OF THE GENUS LOPHODOLOS 13 

Lophodolos indicus Lloyd, 1909a 
Figures 7-8 

Lophodolos indicus Lloyd, 1909a: 167 (original description; single specimen; 
holotype, IMC 1024/1, 53.0 mm; INVESTIGATOR Station 307, off 
Kerala (formerly Travancore) , southwest coast of India: 0-1624 m) . 

Lophodolus indicus, Lloyd, 1909a: pi. 45, fig. 7 (holotype figured) . Regan, 
1925: 563 (comparison with L. acanthognathus) . Regan, 1926: 30 (brief 
description after Lloyd, 1909a; comparison with L. acanthognathus) . 
Regan and Trewavas, 1932: 83 (after Lloyd, 1909a, Regan, 1926) . Ber- 
telsen, 1951: 108 (description after Lloyd, 1909a, Regan and Trewavas, 
1932; comparison with all known material of Lophodolos) . Grey, 1956: 
255-256 (synonymy; vertical distribution) . 

Lophodolus dinema Regan and Trewavas, 1932: 83, pi. 4, fig. 3 (original 
description; single specimen; holotype, ZMUC P92105, 43.0 mm; DANA 
Station 3716(2), South China Sea, 19°18'N, 120°13'E; 3000 m wire; hot- 
tom depth 3225 m; 1400 hr; 22 May 1929). Bertelsen, 1951: 108 (de- 
scription; comparison with all known material of Lophodolos) . Grey, 
1956: 255 (synonymy; vertical distribution) . 

Material. Twenty-two female specimens, 9.5—77.0 mm: IMG 
1(53.0 mm); ISH 5(36.0-75.0 mm); LACM 4(32.5-71.0 
mm) ; MCZ 4(30.0-64.5 mm) ; NIO 1 (57.0 mm) ; SIO 5(9.5- 
77.0 mm); UMML 1(23.0 mm); ZMUC 1(43.0 mm). 

Diagnosis. See key to species. 

Description. Illicium long, 15.2-138.0 (Fig. 1); width of 
escal bulb small, 2.1-5.2 (Fig. 2) ; escal appendages short, 1.2- 
10.5 (Figs. 4, 8); sphenotic spines short, 1.9-6.0 (Fig. 5); 
quadrate spines short, 1.6-5.0 (Fig. 6) ; D. 6-8; A. 5—7; P. 17— 
21 (Table 1) (measurements in percent of SL; spine lengths 
based on specimens greater than 30 mm, fin ray counts on speci- 
mens greater than 20 mm) . 

Rest of characters as for genus. 

Distribution. In the Atlantic Ocean, L. indicus appears to be 
restricted to the eastern side ; seven specimens are known from off 
the continental slope of Africa from 20°N, 21°W, east to the 
Gulf of Guinea and south to approximately 18°S, 10°W. The 
remaining material (15 specimens) is rather evenly distributed 
across the Indian and Pacific oceans between approximately 
4°S and 30°N. The holotype was collected off the southwest 
coast of India ( Fig. 9 ) . 

On the basis of maximum depths reached by fishing gear, 
metamorphosed L. indicus are vertically distributed between 
approximately 750 m and an unknown lower limit. All speci- 
mens larger than 30 mm (18 individuals) were captured by 



14 



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BREVIORA 



No. 425 




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1974 



ANGLERFISHES OF THE GENUS LOPHODOLOS 



15 




figure 8. Esca of Lophodolos indicus, MCZ 47559, 58.0 mm, left lateral 
view. Drawn by Patricia Chaudhuri. 



nets fished below 1000 m; 67 percent of these were captured by 
nets fished below 1500 m. 

Comments. Large specimens of L. indicus (greater than ap- 
proximately 30 mm) are easily distinguished from L. acantho- 
gnathus on the basis of ilHcial and escal appendage lengths alone 
(see key to species). Smaller specimens are more difficult to 
identify (see comments under L. acanthognathus). 

Lophodolus dinema Regan and Trewavas (1932) was de- 
scribed as new on the basis of an escal morphology differing 
from that of L. indicus. These differences, however, are un- 
doubtedly the result of damage. The esca of the holotype of L. 
indicus, originally described by Lloyd (1909a: 167) as being 
''hard but . . . covered with short, shreddy filaments," has lost 



16 



BREVIORA 



No. 425 




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1974 ANGLERFISHES OF THE GENUS LOPHODOLOS 17 

the two bilaterally placed appendages found in the holotype of 
L. dinema and in all known specimens of Lophodolos. Although 
I did not see it, the poor condition of the esca was confirmed by 
a sketch made from the holotype of L. indicus provided by 
A. G. K. Menon of the Zoological Survey of India. Discrepan- 
cies in illicial length (Bertelsen, 1951: 107) are also more ap- 
parent than real. A plot of illicial length against standard length 
( Fig. 1 ) shows the holotype of L. dinema to compare well with 
the material here considered to be L. indicus. In the absence 
of any significant differences, L. dinema is here synonymized 
with L. indicus. 

Species Ingertae Sedis 
Lophodolos biflagellatus Koefoed, 1944, nomen nudum. 
Lophodolus biflagellatus Koefoed, 1944: 7. 

Comments. This name was used by Koefoed in a manuscript 
dated 1918 (not seen by me), and later mentioned in published 
form (Koefoed, 1944: 7) without application to a description 
or type. 

SPECIES RELATIONSHIPS 

Lophodolos acanthognathus and L. indicus are distinguished 
on the basis of five characters: ilHcial length, escal bulb width, 
escal appendage length, sphenotic spine length, and quadrate 
spine length. For most of these characters it is difficult, if not 
impossible, to know whether a character state represents a primi- 
tive or a derived condition. The longer ilHcium of L. indicus 
(Fig. 1), however, is surely a derived state; an increase in illicial 
length is a trend found within other oneirodid genera {Dol- 
opichthys, Oneirodes, and Chaenophryne; Pietsch, 1972b, 1974). 
The width of the escal bulb of L. acanthognathus is like that of 
nearly all other oneirodids; the considerably narrower bulb of 
L. indicus (Fig. 2) is most likely a derived condition. Lopho- 
dolos acanthognathus has significantly longer escal appendages 
than L. indicus (Fig. 4), perhaps representing a derived state; 
longer escal appendages and filaments are found in the more 
derived species of Oneirodes (Pietsch, 1974). The sphenotic 
and quadrate spines of L. acanthognathus are long relative to 
those of L. indicus; either character state, long versus short, may 
represent the derived condition. From this character analysis, it 
is reasonable to speculate that L. indicus is the more derived 
member of the genus. 



18 BREVIORA No. 425 

LITERATURE CITED 

Beebe, William. 1932. Nineteen new species and four post-lan^al deep-sea 

fish. Zoologica (N.Y.) , 13: 47-107. 
1937. Preliminary list of Bermuda deep-sea fish. Zoo- 
logica (N.Y.) , 22(14) : 197-208. 
Bertelsen, E. 1951. The ceratioid fishes. Ontogeny, taxonomy, distribu- 
tion and biology. Dana Rep., 39, 276 pp. 
Bradbury, Margaret G. 1967. The genera of Batfishes (family Ogcoce- 

phalidae) . Copeia, 1967: 399-422. 
Fowler, H. W. 1936. The marine fishes of West Africa. Based on the 

collections of the American Museum Congo Expedition, 1909-1915. 

Bull. Amer. Mus. Nat. Hist., 70 (2) : 607-1493. 
Gregory, W. K. 1933. Fish skulls. A study of the evolution of natural 

mechanisms. Trans. Amer. Phil. Soc., 23: 75-481. 
Grey, Marion. 1955. Notes on a collection of Bermuda deep-sea fishes. 

Fieldiana: Zool., 37: 265-302. 
1956. The distribution of fishes found below a depth of 

2000 meters. Fieldiana: Zool., 36 (2) : 75-337. 
KoEFOED, E. 1944. Pediculati from the "Michael Sars" North Atlantic 

Deep-sea Expedition 1910. Rep. Sci. Res. "Michael Sars" Exped. IV., 

2(1): 11-18. 
Lloyd, R. E. 1909a. A description of the deep-sea fish caught by the 

R.I. M.S. Ship "Investigator" since the year 1900, with supposed evidence 

of mutation in Malthopsis. Mem. Indian Mus., Calcutta, 2(3): 139-180. 
. 1909b. Illustrations of the Zoolog)^ of the Royal Indian 

Marine Survey Ship Investigator under the command of Commander 

W. G. Beauchamp, R.I.M. Fishes, Part 10, Plates 44-50. 
LiiTKEN, Chr. Fr. 1871. Oneirodes eschrichtii Ltk. en ny gronlandsk Tud- 

sefisk. Oversigt over det Kongl. Danske Vidensk. Selsk. Forhandl., 1871: 
56-74. 
Murray, J., and J. Hjort. 1912. The Depths of the Ocean. London: 

Macmillian and Co., Limited, xx + 821 pp. 
NvBELiN, O. 1948. Fishes collected by the "Skagerak" Expedition in the 

eastern Atlantic 1946. K. Vet. O. Vitterh. Samh. Handl., Ser. B, 5(16): 

1-93. 
PiETSCH, T. W. 1969. A remarkable new genus and species of deep-sea 

anglerfish (family Oneirodidae) from off Guadalupe Island, Mexico. 

Copeia, 1969: 365-369. 
. 1972a. A review of the monotypic deep-sea anglerfish 

family Centrophrynidae: taxonomy, distribution and osteology. Copeia, 

1972: 17-47. 

1972b. Ergebnisse der Forschungsreisen des FFS "Walther 



Herwig" nach Siidamerika. XIX. Systematics and distribution of cera- 
tioid fishes of the genus Dolopichthys (family Oneirodidae) with the 
description of a new species. Arch. Fischereiwiss., 23 (1) : 1-28. 



1974 ANGI.ERFISHES OF THE GENUS LOPHODOLOS 19 

. h>74. Osicology and relationships ol deep-sea angleilishes 



ot' the family Oneiiodidae witli a review ol the genus Oneirodes Liitken. 
Bull. Nat. Hist. Mus. Los Angeles Co., Sti., 18: 1 11.'}. 
Reg.\n, C. T. 1925. New ceratioid lishes troin the N. Atlautie, the Caril)- 
beau Sea. and the Gulf of Panama, colleeted by the 'Dana." Ann. Mag. 
Nat. Hist., Ser. 8, 8 {&Z) : 561-567. 

. 1926. The pediculate lishes of the suborder ( .eratioidca. 

Dana Oceanogr. Rep., 2,, 45 pp. 
Regan, C. 1'., and E. Trewavas. 1932. Deep-sea anglerfishes (^Ceratioidea) . 

Dana Rep., 2, 113 pp. 



APR 2 1 1977 



ARVARO 



B R E V I O R'^^A'^^ 

Miiseiiin of Comparative Zoology 



us ISSN 0006-9698 



Cambridge, Mass. 27 November 1974 Number 426 

ASSOCIATION OF URSUS ARCTOS AND 
ARCTODUS SIMUS (MAMMALIA: URSIDAE) 
IN THE LATE PLEISTOCENE OF WYOMING 

BjORN KURTEN^ AND ElAINE AnDERSON^ 

Abstract. The first substantiated association of Ursus arctos and Arctodus 
simus (Mammalia: Ursidae) from a local fauna south of Alaska is reported 
from Little Box Elder Cave, a late Pleistocene site in Converse County, 
Wyoming. Ursus arctos, the grizzly or brown bear, entered the area from 
Alaska at the end of the Wisconsin glaciation, and may have been a factor 
in the extinction of Arctodus simus, the great short-faced bear. 

INTRODUCTION 

The late Pleistocene Carnivora of Little Box Elder Cave, Con- 
verse County, Wyoming, were described by Anderson (1968), 
who noted the presence of the grizzly or brown bear, Ursus arc- 
tos L. The material consists of a number of loose teeth and foot 
bones, most of which belong to a large form of this species. Ex- 
tended comparison has shown, however, that at least one and 
probably two specimens must be referred to a distinct species 
and genus, the extinct short-faced bear, Arctodus simus (Cope). 
This is the first substantiated record of association between these 
two species of bears south of Alaska. The material is in the 
University of Colorado Museum (UCM), Boulder. 

MATERIAL 

Ursus arctos L., Brown bear 

UCM 22289, right Mi. This tooth belonged to a young in- 
dividual and shows hardly any trace of wear. The posterointernal 

^Museum of Zoology, N. Jarnvagsgatan 13, Helsinki, Finland 
'730 Magnolia St., Denver, Colorado 80220 



2 BREvioRA No. 426 

part of the talonid has been lost. The remainder of the tooth is 
well preserved and is similar to the Mi in Recent U . arctos from 
Alaska except for its somewhat larger size ( Table 1 ) . The lower 
carnassial of Arctodus simus, in possessing a powerful trenchant 
trigonid, differs markedly from the specimen at hand, and is also 
considerably larger, as shown in Table 1 . 

UCM 49-iO and 22290, left and right M2. As in No. 22289, 
these two teeth are quite unworn and probably belonged to the 
same individual. The left tooth is much damaged, while the 
right one is intact except for a missing piece of the protoconid, 
and the loss of the anterior root. This root, however, is preserv^ed 
in the left M2. As far as can be seen from the preservation, the 
two teeth are mirror images of each other. 

The occlusal surface is strongly marked, with large, well- 
developed cusps delimited by furrows. Protoconid, metaconid 
and entoconid are all duplicated; the two cusps in a pair are 
subequal in size except for the protoconid, where the anterior 
cusp is noticeably bigger. The posterior rim of the tooth forms 
a small hypoconulid. A well-developed external cingulum curves 
around the hind edge of the tooth; there are no cingula in front 
or internally. 

Despite its large size, approximating to the average in A. 
simus, M2 has typical U. arctos characters. The second molar of 
A. simus differs in being narrow posteriorly, in lacking an ex- 
ternal cingulum, and in having a markedly inward slope to its 
outer wall, as well as in various morphological details of the 
occlusal surface. 

Although these M2 are larger than those of present-day Alas- 
kan Ursus arctos, late Pleistocene specimens of comparable size 
are known from Alaska (Table 2). An analogous decrease in 
size within U. arctos since late Pleistocene times has been docu- 
mented in Europe (Kurten, 1959, 1968). 

USM No. 52-73, first phalanx, probably from the manus. 
The relatively small size of this bone, which has a length of 
37 mm and measures 11.6 mm transversely in the middle, leads 
us to regard it as most probably being U. arctos. It agrees in 
size with those of present-day grizzly bears. 

Arctodus simus (Cope), Short-faced bear 

UCM 22288, left M^ This tooth belonged to an old indivi- 
dual, and the four principal cusps have worn down to the same 
level as the cuspules. The anteroexternal corner of the tooth, the 



1974 ASSOCIATION OF URSUS ARCTOS & ARGTODUS SIMUS 3 

inner and outer roots, and some other portions of the crown have 
been lost; the anterior and posterior roots are preserved. 

In spite of the damage, there can be no doubt about the char- 
acteristic outline of the Arctodus M". It is approximately tri- 
angular in shape, being broad in front and tapering rapidly 
posteriad; the inner wall is straight but the outer wall has a 
rounded bulge at the base of the metacone. In Ursus arctos, M" 
is a relatively longer and narrower tooth, and is not similarly 
tapered towards the hind end of the talon. The specimen 
matches closely the M" in specimens of Arctodus simus from 
Alaska with which it has been compared. Its size is close to the 
average for A. simus from Potter Creek Cave, California (Kur- 
ten, 1 967 ; see also Table 3 ) . 

UCM No. 7-56, left pisiform. The morphological characters 
and relatively slender build of this bone lead us to refer it to 
A. simus. It compares closely with the specimen from Rancho 
La Brea figured by Merriam and Stock (1925), and deviates in 
various respects from a specimen of U. arctos of comparable 
size; the last mentioned is conspicuously heavier in build, as 
shown by the measurements (Table 4). In No. 7-56, the shaft 
is slenderer and the distal boss much more flattened than in 
U. arctos. The size of the specimen is about the same as in ^. 
simus from Rancho La Brea and Frankstown Cave (see Kurten» 
1967: 35, Table 14). 

DISCUSSION 

The bear fossils were found at various levels and locations in 
the cave. As Anderson (1968) pointed out, there has been some 
reworking of the unconsolidated deposit by rodents, especially 
Neotoma cinerea. This probably accounts for the fact that the 
two brovvn bear M2 lay at different levels. The age of the fauna 
as a whole is late Wisconsin. 

As far as we know there is no other locality south of the Fair- 
banks District, Alaska, that shows an association between these 
two species. Ursus arctos has been reported from the Rancho 
La Brea tar pits, which have also yielded A. simus, but as shown 
by Kurten ( 1 960 ) the only specimen definitely referable to the 
former comes from the postglacial Pit 10, where the short-faced 
bear is not present. The ursine bear of the main Rancholabrean 
fauna is the black bear, Ursus americanus Pallas, of which a 
very large form was present in North America during the Wis- 
consin. Its large size has led to confusion with the grizzly bear. 



'4 BREVioRA No. 426 

We suggest that U. arctos entered western United States at the 
end of the Wisconsin glaciation, presumably through the corridor 
between the Cordilleran and Laurentide ice fields, from Alaska, 
which it had colonized some time earlier. Once it had penetrated 
south of the ice sheet it extended its range far beyond its limits 
in historical times, as shown by finds in eastern Canada and the 
United States { Guilday, 1 968 ) . The great short-faced bear may 
have become extinct either as a result of competition with U . 
arctos or because its prey became extinct, or for some other 
reason; but the exact date of its extinction cannot yet be stated. 

ACKNOWLEDGEMENTS 

We would like to thank Peter Robinson, University of Colo- 
rado Museum ; Richard Tedford, American Museum of Natural 
History; and John L. Paradiso, Bird and Mammal Laboratories, 
National Museum of Natural History, for letting us examine 
specimens in their care. We are indebted to National Science 
Foundation Grant No. GB 31287 to Professor Bryan Patterson 
for aid in carrying out this and other work on North American 
Pleistocene mammals. 

ABBREVL\TIONS 

The following abbreviations are used in the tables: 
F : AM — Frick Collection, American Museum of Natural His- 
tory, New York. 

LBEC-UCM ^ Little Box Elder Ca%'e, University of Colorado 

Museum, Boulder. 
LJSNM — National Museum of Natural Histon, AVashington, 

D. C. 
M — Mean 

N — Number in sample 
O.R. — Observed Range 
S.D. — Standard Deviation 



t 



REFERENCES 



Anderson, E. 1968. Fauna of the Little Box Elder Cave, Converse County, 
Wyoming. The Carnivora. Univ. Colorado Stud. Earth Sci., No. 6: 1-59. 

GuiLDAv, J. E. 1968. Grizzly bears from eastern North America. Amer. 
Midi. Nat., 79(1) : 247-250. 

KuRTEN, B. 1959. Rates of evolution in fossil mammals. Cold Springs Har- 
bor Symp. Quant. Biol., 24: 205-215. 



1974 ASSOCIATION OF URSUS ARCTOS & ARCTODUS SIMUS 5 

1960. A skull of the grizzly bear (Ursus arctos L.) from Pit 



10, Rancho La Brea. Contrib. Sci. Los Angeles Co. Mus., 39: 1-7. 

1967. Pleistocene bears of North America. 2. Genus Arctodus, 



short-faced bears. Acta Zoologica Fennica, 117: 1-60. 

1968. Pleistocene Mammals of Europe. London: Weidenfeld 



and Nicholson, and Chicago: Aldine Press. 317 pp. 
Merriam, J. C, AND C. Stock. 1925. Relationships and structure of the 
short-faced bear, Arctotherium, from the Pleistocene of California. Publ. 
Carnegie Inst. Washington, 347 (1) : 1-35. 

Table 1. Measurement of Mi in Ursus arctos and Arctodus simus. 

N O.R. M S.D. 

Trigonid length 
U. arctos 

Recent, Alaska — USNM 40 14.3-17.0 15.90±0.09 0.60 

LBEC UCM 22289 I - 18.0 

A. simus 

Pleistocene 18 21.8-26.1 23.01 ±0.33 1.42 

Trigonid width 
U. arctos 
Recent, Alaska — USNM 40 8.2-11.1 9.94 ±0.11 0.68 

LBEC UCM 22289 1 - U.O 

A. simus 

Pleistocene 20 14.1-16.8 15.50 ±0.16 0.73 

Table 2. Measurements of M2 in Ursus arctos. 

LBEC Pleistocene, Alaska 

UCM 22290 F:AM A-200-6671 
Length 30.6 32.3 

Anterior width 19.5 19.5 

Posterior width 20.0 20.8 

Table 3. Measurements of M2 in Arctodus simus and Ursus arctos. 

N OR. M S.D. 

Length 
A. simus 

Pleistocene 27 33.3-41.4 37.60 ±0.4 2.1 

' LBEC UCM 22288 1 - 35.5 

U. arctos 
Pleistocene, Alaska 1 - 45.0 

Anterior width 
A. simus 
Pleistocene 27 21.3-25.8 23.66 ±0.23 1.20 

LBEC UCM 22288 1 - ca. 22.5 

U. arctos 
Pleistocene. Alaska 1 - 24.0 



6 BREVIORA No. 426 

Table 4. Measurements of Pisiform Bone in Arctodus simus and Ursus arctos. 

A. simus U. arctos 

LBEC UCM 7-56 USNM 199252 

Greatest length 56.0 54.0 

Greatest proximal diameter 31.0 32.0 

Distal boss, long diameter 34.3 30.7 

Distal boss, short diameter 18.5 21.8 

Least width of shaft 15.4 16.8 



'M/i-' APR 2 11977 






B R E V I O R-A 

Museum of Comparative Zoology 



us ISSN 000&-9698 



Cambridge, Mass. 27 November 1974 Number 427 

THE STRATIGRAPHY OF THE 
PERMIAN WICHITA REDBEDS OF TEXAS^ 

Alfred Sherwood Romer'^ 

Abstract. A description is given of the topography of the Hmestones and 
sandstones that form the formation boundaries between the six units com- 
prising the continental redbeds of north central Texas; the results are 
presented in two maps. 

The Early Permian redbeds of Texas, those of the Clear Fork, 
and even more notably those of the stiU earlier Wichita Group, 
are of major importance in the history of vertebrates. These are 
the oldest beds in which there is present an abundant fauna of 
continental type. In earlier. Carboniferous deposits of various 
areas have been found a very considerable number of amphibian 
types, and even, in the late Carboniferous, early reptiles. But 
almost without exception Carboniferous deposits containing tetra- 
pod vertebrates represent coal-swamp conditions, and it is not 
until we reach the Texas Wichita redbeds at the beginning of 
Permian times that we find a truly continental fauna. Speci- 
mens, to the number of several thousands, representing scores of 
amphibian and early reptile types, have been collected in these 
beds for nearly a century. It is clear that these beds, with more 
than a thousand feet of deposits, represent a very considerable 
period of time during which a fair amount of evolutionary 
progress and faunal change took place. Farther to the south 
arid southwest the Wichita beds are mainly marine in nature, 
with identifiable limestones, and there competent stratigraphic 
work has been done. But with the transition to continental beds 
to the north and east the limestones fade out, and almost nothing 

^This paper was in essentially completed form at the time of Professor 
Romer's death in November, 1973. Miss Nelda Wright kindly finished the 
task of preparing the manuscript and maps for publication. (Ed.) 

^Museum of Comparative Zoology, Harvard University. 



2 BREVIORA No. 427 

has been done in the past to sort out the sequence of formations 
in the redbeds portion of the Wichita. 

In default of work here by the geologists, I decided a number 
of years ago (1960) that although not a stratigrapher or proper 
geologist, I myself must attempt to work out the sequence of 
formations in the Wichita beds. 

The task, at first, seemed almost hopeless. Except on the 
fringes of the area, limestones, to serve as formation boundaries, 
were almost nonexistent. Sandstones could be observed here and 
there, but it seemed probable that these were channel sandstones 
of limited extent. The one saving grace was that almost all of 
the area concerned was oil-bearing, and that in consequence 
thousands of well logs were available. In these logs, identifiable 
limestone markers of late Carboniferous age could be located. 
Assuming (hopefully) that deposition of sediments was fairly 
uniform over the area concerned, it would be possible to lay out 
a sequence of formations by calculating the distance to the sur- 
face from such limestones and thus plot out a rough stratigraphic 
sequence. 

A further discouragement lay in the fact that for almost aU 
of the area no topographic maps were available. Apart from 
highway maps and blueprint land-ownership maps of the counties 
concerned ( drawn up for the benefit of oil lease men ) , the only 
sources available were Department of Agriculture air photos, 
which show streams, hills and roads, but do not, of course, give 
any indications of elevation. 

All in all, the prospect was most discouraging. But as I began 
work, I found that both nature and man rendered valuable aid. 
( 1 ) As I said above, surface markers to distinguish formation 
boundaries appeared to be lacking. This proved, however, not 
to be the case. Upon study of the sandstones encountered, many 
of them proved to be wide ranging, and could be followed for 
a considerable distance cross countr)'. Further, in most cases 
limestones that, to the southwest, were used as formation 
boundary markers, were found to change s^radually to the north- 
east into sandy limestones, then into "limey" sandstones and 
straight sandstones, which could be traced across the entire area 
concerned.^ 

^Had I read more carefully Cummins' last paper (1897) on the Wichita- 
Albany problem, I would have seen my discovery of this condition to have 
been anticipated by him. He states: "We found that a limestone in the 
Albany Division . . . gradually changed in composition to a calcareous sandy 
clay. . . . other limestone beds in the Albany division when traced to the 
northeastward would gradually pass into sandstone." 



1974 PERMIAN WICHITA REDBEDS 3 

(2) Major aid came from another source. As noted above, 
almost no topographic maps of the area were available when I 
began to work. At about this time, however, an arrangement 
was made between the Texas Water Development Board and 
the Topographic Branch of the U. S. Geological Survey, to map 
a larger area, including almost every bit of the Wichita redbeds 
region, on a scale of 1 : 24,000. The work proceeded rapidly 
and presently proofs and finally finished sheets of the whole 
area became available. These were of inestimable value to me 
— most notably in giving accurate elevations ( doing elevations by 
aneroid in the highly variable weather conditions of the Texas 
prairies is most unsatisfactory). 

( 3 ) A final aid in this work came as a result of the decision 
of the Texas Bureau of Economic Geology to prepare a geological 
map of the State, at a scale of 1 : 250,000, under the direction 
of Virgil Barnes. One of the first sheeets attempted was the 
Sherman Sheet, along the north border of the State. The Cre- 
taceous covers most of the territory, but much of the western 
margin, in Montague County, lay in the Permian. Almost no 
definite formation markers were available in this area, but it 
was found (as I had found) that certain sandstone beds could 
be traced for a considerable distance. These were followed out 
by J. H. McGowen westward across Montague County and into 
Clay County to the west. These sandstones were merely given 
numbers on the published Sherman Sheet; I found, however, 
that certain of them were identical with formation boundaries 
that I had been following eastward. In almost every instance, 
McGo wen's findings and mine coincided. It was a pleasure to 
have my work independently confirmed and, in fact, in a few 
areas in Clay and Montague Counties, I saved my weary feet 
and accepted McGowen's findings in completing my course over 
to the Cretaceous boundarv. 

I owe thanks to a very considerable number of people and 
institutions for aid during the course of this work. Notably, I 
am deeply indebted to my wife, Ruth Hibbard Romer, who 
accompanied me on almost all of my trips to the area, furnished 
my transportation and day after day picked me up, footsore and 
weary, after a long trek across the cow pastures. John Kay, con- 
sulting geologist of Wichita Falls, who is an authority on the 
geology of the Wichita region, aided throughout with encourage- 
ment, advice, and specific data. The Gulf and Humble Oil 
companies gave me access to their well log collections and to 
unpublished maps, surface and subsurface, and the first-named 



4 BREVIORA No. 427 

company presented me with a large collection of duplicate well 
logs. Robert Roth of Wichita Falls gave useful advice in Wichita 
stratigraphy. Robert Craig, oil geologist of Olney, gave me the 
use of a very valuable series of well logs of Young County. I 
am indebted to Frank Gouin, oil geologist of Duncan, Okla- 
homa, for interesting discussions of the Montague County beds. 
Virgil Barnes aided greatly by making available to me Mc- 
Gowen's tracings. Adolph H. Witte of Clay County, who has 
done much work in archaeology and paleontology, gave much 
helpful advice. The maps here published were drawn by Carol 
Jones. 

I cannot refrain from mentioning the late Fred B. Plum_mer, 
of the University of Texas and the Bureau of Economic Geology, 
who first interested me in the stratigraphy of these beds and who, 
had he not died at an unseemly early age, would have been 
deeply interested in the present work. 

It is impossible in a short space to give thanks to the many 
landowners who have allowed me to wander over their pastures. 
My wife and I are most especially indebted to Mr. and Mrs. 
G. F. Boone and L. D. Boone of Godwin Creek, whom we have 
long cherished as valued friends, to James R. Parkey who has 
given us ready access to various areas that he owns in the Little 
Wichita country, and John Robinson of Archer City, ever hos- 
pitable to "bone hunters." 

I am much indebted to the National Science Foundation for 
support of part of my earlier Texas work, for support of a final 
trip to the Texas beds in 1973, and for publication of this paper. 

WICHITA STRATIGRAPHY 

The first student of the Wichita beds was W. F. Cummins. 
Originally a frontier preacher, he was engaged by Cope to col- 
lect fossil vertebrates in the Texas redbeds, then turned geologist, 
served on the Texas Geological Survey during the few years of 
its existence, and later became geologist for the Southern Pacific 
Railroad. In his early work for the Texas Sur\^ey, Cummins 
(1891) believed conditions to differ north and south of the 
Brazos River. He established a Cisco Division as forming the 
uppermost section of the Carboniferous in the northern area. 
Included in the Cisco were the coal beds (which he lumped at 
that time as "Coal number 7" and, as seen on his plate VII, 
considered the top of the Cisco to lie not far above this coal). 
The typical coals of this area are contained in the Harpers\ille 



1974 PERMIAN WICHITA REDBEDS 5 

Formation of most writers. In the northern region he believed 
the Cisco to be directly overlain by the Wichita beds, which thus, 
as later identified, begin with the Pueblo Formation (in which 
are found the lowest redbeds in southeastern Archer County). 
In this northern area he believed the top of the Wichita beds to 
lie at a double limestone seen along the Big Wichita River a 
few miles west of the Archer-Baylor county line (1891: 402). 
This limestone is clearly the Bead Mountain Limestone, forming 
the boundary between Belle Plains and Clyde formations. Cum- 
mins' original Wichita thus included, in ascending order, the 
Pueblo-Moran-Putnam-Admiral-Belle Plains formations of later 
terminology; the Clyde Formation, later considered an integral 
part of the Wichita, was in this discussion thought to be a lower 
element of the Clear Fork. 

Farther south, beyond the Brazos in Young and Stephens, 
Throckmorton and Shackleford counties, Cummins found a dif- 
ferent situation. Above the Cisco are formations that are mainly 
marine in nature, which he did not realize were identical with 
his Wichita beds to the north. He believed these beds, which he 
termed the Albany Division, to be a terminal part of the Car- 
boniferous intercalated between the Cisco and the Permian red- 
beds. The upper boundary of the Albany beds (1891 : 404) he 
believed to He between California Creek and the Clear Fork, 
about on the Shackelford-Haskell County boundary. He thus 
considered the Lueders as the top of his Albany beds, above 
which lay the Clear Fork redbeds. 

Two years later (1893, especially p. 223) Cummins began to 
suspect that his Albany beds were merely a different facies of 
the Wichita beds. And in 1897 he confirms this suspicion, and 
definitely traces certain "Albany" beds northward into the 
"Wichita" region with a transformation of their character from 
marine to continental in nature. As a result, the term "Albany" 
was abandoned and the pre-Clear Fork Permian beds were 
termed Wichita — although some confusion remained as to 
boundaries between Cisco and Wichita and between Wichita 
and Clear Fork. 

For many years little was added to our knowledge of these 
beds. Adams (1903) and Gordon (1911 (with others), 1913) 
confirmed Cummins' identification of the Wichita and Albany, 
and Gordon reasonably concluded that in the northern area the 
beds from the Bead Mountain Limestone to Lueders should be 
included in the Wichita. 



6 BREVIORA No. 427 

A landmark in the history of the group was the publication 
in 1922 of "Stratigraphy of the Pennsylvanian Formations of 
North-Central Texas" by F. B. Plummer and R. C. Moore. 
While their attention was centered on the late Carboniferous, 
the Wichita formations were discussed as well. The beds which 
Cummins considered to constitute his Cisco division were divided, 
in ascending order, into the Graham, Thrifty, and Harpersville 
formations (the last including the coal beds). Cummins con- 
sidered all higher beds as part of his Wichita. But since at the 
time of publication of Plummer and Moore's paper the Carbonif- 
erous-Permian boundary was believed to be at a considerably 
higher level, three further formations — Pueblo, Moran, and 
Putnam — were included by them in the Cisco, and only the 
formations lying above the Coleman Junction Limestone at the 
top of the Putnam Formation — Admiral, Belle Plains, and 
Clyde formations and, finally the Lueders Limestone — were 
considered to constitute the Wichita Group. 

Subsequent to the publication of Plummer and Moore's basic 
work, the stratigraphy of the Cisco and Wichita has been dis- 
cussed by a number of workers. For example, Sellards, in the 
comprehensive "Geology of Texas" (1933), follows in general 
Plummer and Moore, but since by that time it was generally 
agreed that the Carboniferous-Permian boundary had been 
placed too high in the section, the Moran and Putnam forma- 
tions were included in the Wichita Group. In 1940, M. G. 
Cheney, oil geologist and an able student of Texas geology, pro- 
posed a radical change in treatment. Former "groups" became 
"series"; the former formations became "groups" and were 
subdivided into rather thin formations. Durino^ the years pre- 
ceding this publication the invertebrate paleontologists had estab- 
lished a sequence of marine Permian beds in West Texas, termed 
the Wolfcamp and Leonard Series, the base of the Wolfcamp 
being considered the base of the Permian. Chenev nrooosed 
abandoning the established terms "Wichita" and "Clear Fork" 
and substituting the West Texas local terminolos^v. The evidence 
of foraminifera indicates that the base of the Wolfcamn can be 
equated with a point in the Waldrip shales, somev/hat below 
the top of Harpersville. Cheney solves this problem by abolishing 
the Harpersville "series," the top levels being included in the 
Pueblo, and the rest of the Harpers\ille being lumped with the 
Thrifty. The foraminiferal evidence indicates equivalence of 
the top of the Wolfcamp with about the middle Admiral. Cheney 



1974 PERMIAN WICHITA REDBEDS 7 

hence reduced the Admiral by half, adding the upper part of 
the formation to the Belle Plains. 

Moore returned to the Texas redbeds region in 1949 with the 
study of the geology of the Permian in the Colorado River region. 
He followed Cheney in part, by including the upper part of the 
Harpersville in the Pueblo, and including the upper part of the 
Admiral in the Belle Plains. However, he refused to raise the 
"formations" to "series" level. Furthermore, he retained the 
term "Wichita Group" for formations from the Pueblo Forma- 
tion (expanded) to and including the Lueders, but parallels 
Cheney in also noting "beds of Wolf camp age" and "beds of 
Leonard (?) age" at the levels given by Cheney. 

In this present attempt at interpreting the stratigraphy of the 
Wichita beds, I have essentially follo^ved Plummer and Moore. 
The finer subdivisions proposed by Cheney may be followed in 
the marine section, but are impossible to sleuth out in the con- 
tinental beds. Nor can the subdivision proposed by him within 
the Harpersville and Admiral formations be readily followed 
in the continental areas with which we are concerned. I have 
adopted the base of the Pueblo as the base of the Wichita. This 
is in accord with Cummins' original definition of the Wichita, 
since the actual base of the redbeds type of deposit is at the 
base of the Pueblo Formation. Although I am far from certain 
that the base of the Wolfcamp of West Texas has any neces- 
sary relation to the true Carboniferous-Permian boundary, 
this equivalent is but slightly below the base of the Pueblo. 
It is generally overlooked by invertebrate paleontologists that, 
considering that the extent of the Permian was for a long time 
(and still is) a rather vague and ill-defined matter, the real 
point in question is not the base of the Permian but the top of 
the Carboniferous, a matter for settlement by paleobotanists. But 
both invertebrate and botanical evidence agree that the Permian 
base is a short distance below the base of the Pueblo, and since 
this exact point cannot be accurately determined in the conti- 
nental beds, the slightly higher Saddle Creek Limestone, which 
can be readily followed, seems a satisfactory point for Cisco- 
Wichita division. 

Methods. The results of my field work are shown on the three 
accompanying maps, on which I have attempted to exhibit the 
subdivision of the beds into six successive formations, from the 
underlying Cisco beds of the Carboniferous up to the Clyde 
Formation and the Lueders Limestones, which cap the Wichita 



8 BREVIORA No. 427 

and form the boundary with the overlying Clear Fork. The 
formation boundaries, as traced, were at first entered on the 
air photographs, later on the 1 : 24,000 topographic sheets. It is, 
of course, impractical to publish them on this scale. Maps 2 
and 3 are executed on a two-miles-to-the-inch scale, which will, 
I think, be sufficient for future workers to locate the horizon of 
their finds with reasonable accuracy. 

The method followed was to pick up each successive limestone 
used as a formation boundary where already known and map- 
ped, in the southwestern part of the region, and then follow it 
northward and eastward cross-country as it changed toward and 
to the condition of a sandstone. In some areas a continuous 
tracing was possible. Over much of the region, however, the 
rolling prairie surface makes this impossible, and I have had 
to seek out occasional small outcrops or detached slabs in the 
pasture grass, much in the fashion of a "paper chase.^' Under 
such conditions, of course, it was possible to stray from one 
sandstone to another, above or below. But over most of the ter- 
ritory there exists such a profusion of well logs that a check on 
elevations above the underlying hmestones of the Cisco Group 
was present as a corrective. 

All the stratigraphic studies mentioned earlier have been made 
in the region to the south of the true redbeds area; almost no 
previous attempts at stratigraphic subdivisions of the continental 
beds have been made. The sole exception was that in the 1920's, 
a time at which it was believed that the Coleman Junction Lime- 
stone represented the Carboniferous-Permian bondar\^, a recon- 
naissance was made of the probable course of this horizon from 
the point at which the limestone disappears in southwest Archer 
County north and east to the Red River (Timms, 1928). Some 
years ago (1958) in a general essay on the redbeds and their 
fauna I included a rough sketch of the probable formation 
boundaries in the redbeds area. 

The general area to be considered is bounded on the north by 
the Red River; to the west by the Clear Fork beds above the 
Lueders Limestone, running north to south through Wilbarger, 
Baylor and Throckmorton counties. To the east, in Montague 
County, the Wichita beds disappear beneath the Cretaceous 
deposits. To the south we reach the base of the Wichita beds 
along a line somewhat south of the Jack County boundan'. To 
the southwest the formations of the Wichita Group continue, but 
gradually change from continental to marine beds - — that is, 



( 



1974 PERMIAN WICHITA REDBEDS 9 

from "Wichita" type beds to sediments of "Albany" nature. South 
of the Brazos River vertebrate fossils become scarce, and very 
few have been found in the Wichita beds beyond the southern 
boundary of Throckmorton County. 

The geologic structure of the area is a simple one. The area 
is in general a northern continuation of the Bend arch. In 
eastern Young County and northward the beds dip to the north ; 
west of this line, the dip is to the northwest (Hubbard and 
Thompson, 1926). In the southern part of the region the dip 
is on the order of 40-50 feet to the mile. Farther north the 
dip decreases, and in the upper beds, found on the surface 
toward the Red River, the beds are nearly horizontal. Near the 
river, the deeper beds in certain areas have been strongly affected 
by the east-west Electra arch and, farther east, by the Muenster 
arch. Arch activity, however, appears to have ceased before 
deposition of the surface beds here, and in general, these struc- 
tures have had no effect on the surface stratigraphy. To the east, 
in southern Montague County we encounter the margin of the 
Fort Worth basin, with strong dips to the east and northeast in 
the lower beds. 

One tends to think of the change in the nature of the Wichita 
beds as being a north-to-south shift from continental to marine. 
Actually it seems that it is an east-to-west transition. The general 
redbeds area appears to have been a lowland, with ( presumably ) 
high land to the east and a sea to the west. As is known from 
well logs, the Wichita redbeds formations became mainly marine 
west of a line extending from central Wilbarger County south 
through central Baylor and Throckmorton counties. In the 
eastern parts of these counties there are occasional persistent 
limestones, but redbeds tend to dominate and almost no lime- 
stones persist east of the east line of these counties. 

As an aid to future workers who wish to check — or correct 
— my findings, I herewith add some detail as to the nature of 
my work on the various formation boundaries. 

The Saddle Creek Limestone 

As noted above, I consider the Pueblo Formation to be the 
basal member of the Wichita group; and I consider the Saddle 
Creek Limestone, at the top of the Harpersville, as furnishing a 
close approximation to the Carboniferous-Permian boundary. 

The Saddle Creek Limestone is well developed in the more 
marine sections of the Wichita to the south, and can be followed 



10 BREVIORA No. 427 

north as far as the Clear Fork of the Brazos, not far south of 
the Young County line. It can be traced into southwestern 
Young County only with difficulty and with doubt. Plummer 
and Moore identify it for a distance west of the Salt Fork south- 
west of Newcastle, but it is probable that this is the somewhat 
lower Belknap Limestone, as is also presumably the case of the 
supposed Saddle Creek in this area marked on the 1937 Co- 
operative geological map (Plummer and Fuqua, 1937) . Lee and 
colleagues (1938; cf. Cheney, 1940: 91 and fig. 10) figure the 
Saddle Creek, although with some doubt, at the head of Ratliff 
Branch in southwestern Young County, Here the limestone, 
feebly developed, is part of a thick sandstone layer that can be 
readily followed to the north and east across Young County, 
where it lies in proper relation to the underlying limestones in 
the Harpersville.^ From the point mentioned above, the sand- 
stone beds here accepted as the Saddle Creek equivalent turn 
westward along the south margin of the valley of Gibbens Creek, 
cross that creek and run northeastward along the north side of 
this valley to reach a prominent bluff close to the Brazos and 
directly west of Fort Belknap. The Saddle Creek Limestone 
then turns west, and becoming less well marked, descends down 
the west side of the valley of Postoak Creek and reaches a bluff 
south of the Salt Fork at the mouth of Elm Creek. It continues 
west south of Elm Creek, to disappear into the Salt Fork allu- 
vium about a mile east of Proffitt. The Saddle Creek reappears 
on the north bank, only obscurely west of the mouth of Paint 
Creek (California Creek), but east of that creek capping Deer 
Head Bluff north of the Salt Fork bottoms. East of this bluff 
it turns northward west of Big Skid Creek and can be traced 
with some difficulty eastward across the flat country' at the head 
of this creek and then southward along a low ridge west of 
Peveler Creek. Returning northward to cross this last creek, the 
outcrop continues eastward along the hills north of Newcastle 
to a prominent point about four miles northeast of Newcastle 
and a mile west of Salt Creek. From this point a series of out- 
liers extends northeastward toward Jean, but the main outcrop 

^Galloway, in an interesting study of the Harpersville in subsurface (Gal- 
loway and Brown, 1972) , gives a surface map on which the assumed Saddle 
Creek Limestone is shown for several areas in Young and Jack counties. 
Different areas indicated on this map, however, show the supposed Saddle 
Creek at several different levels, ranging from that of mv assumed Saddle 
Creek up to that of the Camp Colorado, nearly 200 feet higher. 



1974 PERMIAN WICHITA REDBEDS 11 

turns northward along the west margin of the Salt Creek valley, 
descending to cross this creek a mile northeast of True cemetery. 
The outcrop turns southeastward for two miles, swings north- 
ward to cross Little Salt Creek, then southward and again north- 
ward to obscurely circumnavigate a flat area east of Jean. 
The outcrop turns south for about three miles, then north for 
six miles to Farmer, at a level of about 11 50 feet, mainly follow- 
ing the base of the hills west of the road leading from State 
Highway 199 north to Farmer. 

Southeast of this area, the country rises to the Loving region. 
My well records for this area are sparse, but it seems probable 
that there were several outliers of the Saddle Creek in this area, 
the principal ones being at the Loving settlement and along a 
ridge running eastward toward the county line. Galloway (Gal- 
loway and Brown, 1972) considers these beds to lie within the 
underlying Harpersville Formation, presumably because he gen- 
erally places the Saddle Creek member at a higher level strati- 
graphically than I do. 

From Farmer the main outcrop runs eastward two miles along 
a ridge between two tributaries of Brushy Creek, then westward 
south of these tributaries to a point north of Farmer. North of 
this tributary it runs eastward along a ridge, which becomes 
prominently developed, for about three miles, with outliers on 
Rattlesnake Mountain and Bare Mountain, and then turns 
northward, only to turn westward up a further northern branch 
of Brushy Creek. After crossing this branch near its head, the 
Saddle Creek comes east again several miles to Spy Knob. 
Thence the outcrop runs for some miles northwest, then north- 
east, then southeast, in so doing outlining a semicircle around 
the margins of the Prideaux structure (highly important in the 
days of shallow oil production ) . After crossing the Windthorst- 
Loving highway, the Saddle Creek outcrop (now in southeastern 
Archer County) runs eastward along the southern margin of a 
ridge for several miles, almost reaching the West Fork of the 
Trinity River. It then returns westward north of this ridge and 
then turns north and northwest, to subside to the level of the 
West Fork near its crossing by the Windthorst-Loving road, at 
about 1,000 feet. 

We are now entering a wild region, where the West Fork and 
its tributaries have cut deep valleys, capped by sandstones and 
covered by scrub oak and tangles of vines, making a very com- 
plicated pattern. As noted below, the main outcrop of the Saddle 



12 BREvioRA No. 427 

Creek extends eastward north of the West Fork along a general 
line south of the north border of Jack County, with a general 
elevation of about 1,000 feet close to the county boundary, but 
somewhat higher farther south. To the south, beyond the West 
Fork, are large areas of hills and plateaus, sandstone capped, 
which lie at higher levels, and which, by such well-log evidence 
as is available to me, indicate them to be extensive outliers of 
the Saddle Creek. ^ The most westerly of major outliers of this 
sort is one whose southwestern extremity is at Markley and ex- 
tends northeast about five miles to a point south of the mouth 
of Brushy Creek and runs eastward a similar distance alonsr the 
north side of Plum Creek. Much larger is a tableland that oc- 
cupies the area betv/een the valleys of Plum Creek and Cameron 
Creek and extends from three to five miles south of the West 
Fork and includes an area of 20 square miles or so. Farther 
east a smaller outlier lies between Cameron Creek and Roberts 
Prairie Branch and a final, still smaller, outlier is found east 
of this branch. Farther southeast, it is probable that the top of 
the Indian Hills attains the Saddle Creek level. 

After crossing the W^est Fork, the main outcrop of the Saddle 
Creek, as noted above, runs eastward, roughly parallel to the 
Jack-Clay county boundary and some miles to the south. For 
the first mile or so below the crossing- there is little evidence of 
the presence of the Saddle Creek in the alluvial river bottom, 
but east of the Jack County line it is visible as a sandstone low 
down toward the river level. Its eastward course is a zig-zag 
one, the outcrop running to the north up successive creek vallevs 
and rising southward to bluffs north of the "West Fork. A mile 
east of the x\ntelope-Jacksboro highway it extends a mile to the 
north up the valley of Flat Creek, where its elevation drops 
somewhat below 1,000 feet, and then returns southward to a 
river bluff at 1 ,040 feet — an elevation that matches that of the 
outlier south of the ri\'er. Four miles east of the highway cross- 
ing, it runs north a short distance in a \'alley in the Mount Lebo 
region, then returns south to cap a high river bluff at about 
1 ,050 feet. A mile further east lies Lodge Creek, a major north- 
ern tributary of the West Fork; the outcrop extends north up 

^Galloway (Galloway and Brown, 1972) believes these sandstones to lie 
within the Harpersville; but this belief is due to the fact that the outcrop 
to the north, which he indicates as the Saddle Creek, is quite surely the 
Camp Colorado, nearly 200 feet higher in the section. 



1974 PERMIAN WICHITA REDBEDS 13 

this valley to well toward the county line southwest of Shannon, 
dropping below the 1,000-foot level in elevation. East of this 
creek the West Fork tends to swing to the southeast, and the 
main outcrop, continuing eastward, tends to leave the river, 
althouo^h east of Lods^e Creek outliers form bluffs at about 
1,050 to 1,080 feet. The Saddle Creek again extends well to 
the north up Turkey Creek, next to the east, but beyond this 
creek the outcrop turns eastward around the margins of the 
creek valley, sending, however, a high ridge southward and then 
westward to reach an elevation close to 1,100 feet. Next to the 
east is Jones Creek, which the Saddle Creek ascends to Postoak 
settlement. East of Postoak the Saddle Creek extends southward 
several miles along a high but narrow ridge, bifurcate distally, 
with an elevation now over 1,100 feet. East of this ridge the 
Saddle Creek runs northward up the north fork of Crooked 
Creek, to end in a "flat" about two miles in circumference, where 
there are few exposures except in road margins. Descending 
this creek branch, it runs about two miles east to ascend the east 
branch of Crooked Creek to a deep valley north of Galliher 
Mountain. East of this branch it runs southeast and east for 
about four miles along the summit of gentle slopes, past Truce 
church, rising as it goes, to reach a ridge at the southwest corner 
of Montague County at an elevation of about 1,150 feet. It then 
turns northward alon? a bluff for somewhat over two miles, 
losing altitude, to en^er the southeast corner of Clay County at 
about 1,090 feet. There are certainly outHers to the northeast 
of this bluff, and I have mapped sandstone ledges here that are 
probably Saddle Creek equivalents. From the southeast corner 
of Clay County the Saddle Creek turns westward along the foot 
of the hills south of Newport. 

From this point eastward my subsurface data are not sufficient 
for me to be certain of the position of the Saddle Creek. There 
is certainly a sharp dip to the northeast, where we are entering 
the Fort Worth basin. It appears to be represented in hiUs north 
and northeast of Newport along the course of Big Sandy Creek 
toward and to the Montague County line and on northeast 
to Prairie Branch. Crossing this branch it appears to be con- 
tinued by sandstones following the north shores of Lake Amon 
G. Carter, and then following for some distance up the valleys 
of Jones Creek and East Jones Creek, disappears under the 
Cretaceous about four miles south of Bowie. 



14 BREvioRA No. 427 

Camp Colorado Limestone 

The uppermost member of the Pueblo Formation is the Camp 
Colorado Limestone, which separates the Pueblo from the 
Moran Formation. It has long been known farther south, and 
is rather incompletely shown on the southwestern part of the 
geological map of Young County (Plummer and Fuqua, 1937), 
running north close to the Throckmorton County line northward 
toward Elm Creek. From west of Murray in southwestern Young 
County, it runs northward about three miles along the west edge 
of the Fish Creek drainage area, then turns back southwest for 
two miles east of Dr\' Branch of Elm Creek, then traces north- 
ward west of Dry Branch on one side or the other of the county 
line. It follows the west side of Drv Branch almost to Elm 
Creek, ending this course in a prominent bluff. It then turns 
back south along gentle slopes east of Meyers Branch, which it 
crosses about two miles south of Elm Creek. The Camp Colo- 
rado is not exposed along its course down the west side of Meyers 
Branch except at the foot of the bluff west of the branch close 
to Elm Creek. A mile west of this point the Camp Colorado 
can be seen at the bottom of the channels of Elm Creek and its 
tributary Bush Knob Creek. 

North of Elm Creek slopes are gentle, but occasional traces 
of the Camp Colorado can be made out as it runs northeast- 
ward, gaining slowly in elevation and for some distance lying 
close to the state highway from Newcastle to Throckmorton. By 
two miles east of the county line it can be traced along the slopes 
of low hills north of this highway. It then turns northward along 
a low bluff to disappear in the Brazos alluvium near the mouth 
of Boggy Creek. During this segment of its course the Camp 
Colorado is gradually losing its calcareous nature and is in 
process of changing into a sandstone. 

The Camp Colorado reappears on the east bank of the Brazos 
a mile to the north, in a low bluff west of the mouth of Rabbit 
Creek. It is obscure in crossing this creek, but east of this it 
ascends up a small tributary of the creek to the divide between 
Rabbit and Paint creeks, with a large outlier to the south. It 
then runs about three miles to the northeast along the west slopes 
of the Paint Creek valley, crosses this creek and swings east and 
south to a prominent south-facing bluff on the Jeffries ranch. 
Here it sharply reverses direction, and runs north and somewhat 
east, descending to cross Salt Creek somewhat over a mile south 
of Olney. East of Salt Creek it swings for a mile up the valley 



1974 PERMIAN WICHITA REDBEDS 15 

of Willow Pond Creek, then turns back southwest to run east- 
ward along gentle slopes for two miles to Pleasant Valley church. 
It then turns northward and somewhat eastward (poorly ex- 
posed) for two miles to gain the east- west ridge separating the 
Brazos drainage from that of the West Fork of the Trinity River. 
It crosses to the north through a low spot in this ridge, but 
outliers extend eastward along this ridge for about four and 
one-half miles. The main outcrop turns west, not far from the 
Young-Archer County line, to swing around the headwaters of 
the South Fork of the West Fork of the Trinity River. It con- 
tinues northeastward for about eight miles down the west side 
of this fork, with conspicuous outliers on the east side of this 
creek. Crossing the West Fork proper, it continues eastward on 
the side of this small river, keeping at a level of about 1,050 
feet not far from the creek for about 10 miles. Beyond this point 
the West Branch is gradually descending and swinging to the 
southeast and the Camp Colorado, keeping at roughly 1,050 
feet, gradually diverges from the river, running some distance 
up Waters Branch and Darnell Branch as it approaches the 
Archer-Clay County line. It runs eastward north of Antelope 
and here meets the westward end of a line Pss, traced by 
McGowen for the Sherman Sheet of the Texas geological map 
mentioned earlier. From this point eastward my tracing of the 
Camp Colorado outcrop and McGowen's Pss coincide almost per- 
fectly (except that I am doubtful of certain southern outliers of 
his where, I think, the south-to-north dip of the beds is not fully 
taken into account). The outcrop continues eastward close to 
the Jack County-Clay County boundary, at an elevation close 
to 1,050 feet. It dips northward up the valley of Flat Creek, 
just east of Antelope, farther to the north up the valley of 
Willow Creek, west of Shannon and again up a small valley 
near that settlement. The outcrop continues east, at the top of 
low south-facing hills, turning north up the valley of Turkey 
Creek west of Prospect and, to a lesser degree, up a small branch 
east of that settlement. It then runs south two and one-half 
miles to a hiU two miles west of Postoak and then runs north- 
east along the west slopes of Jones Creek for a half a dozen 
miles. Thence it continues eastward in an irregular course, 
again capping south-facing hills, for another half dozen miles, 
entering the drainage of Big Sandy Creek north of Newport. 
Near the Clay-Montague County line it turns west up the valley 
of Prairie Branch; it then follows eastward down the north side 



16 BREvioRA No. 427 

of Prairie Branch to about the county line, then retreats north- 
west up a branch of this creek toward Vashti before returning 
eastward, and, after some miles, turning for some distance up 
East Prairie Branch for about one and one-half miles. East of 
this creek it runs eastward along bluffs well north of Lake Amon 
G. Carter (with a deep "incision" for Trail Creek). West of 
Briar Creek it swings northward for about four and one-half 
miles to a point west of Bowie, and then, after returning' some 
distance down the east bank of this creek, turns eastward to end 
beneath the Cretaceous cover. 

Sedwick Limestone 

Sedwick limestone, being the upper element of the Moran 
Formation is, again, well developed in the counties to the south- 
west of the region with which we are here concerned. It is 
shown, in somewhat incomplete fashion, on the 1937 Throck- 
morton County map (Hornberger, 1937), running north and 
somewhat east toward Elm Creek. I began tracing this lime- 
stone at a point about two and one-half miles west of the Young- 
Throckmorton County line, and about three miles south of Elm 
Creek. The Sedwick here is following north a ridge between 
Mevers Branch and an unnamed small creek to the west. With 
a slight interruption the Sedwick follows this ridge to within 
about half a mile of Elm Creek and then turns back southwest 
to a crossing of this unnamed creek. I could not trace the 
Sedwick down the even slopes west of this creek until, within 
about a mile of Elm Creek, the limestone is seen on a low ridge. 
The Sedwick then turns back southwest, east of Bush Knob 
Creek, to cross that creek at about three and one-half miles 
south of its mouth. Subsurface logs indicate that it again turns 
northward, but I found no surface indication of it until it is 
exposed in the bed of Elm Creek at a ranch road crossing some 
miles to the northwest. 

North of Elm Creek, in a fashion comparable to the Camp 
Colorado a few miles to the east, indications of the limestone 
gradually become apparent, and it gradually ascends the north 
slopes of the Elm Creek Valley in a zig-zag fashion, until, about 
a mile west of the county line, it crosses north out of the Elm 
Creek drainage into that of small western tributaries of the 
Brazos, along which it runs northward to Bogg)' Creek, east of 
Elbert. In this stretch the Sedwick maintains its character as 



1974 PERMIAN WICHITA REDBEDS 17 

a somewhat sandy limestone, and is accompanied by a shale 
layer containing Myalina. At Boggy Creek it turns westward, 
and is traceable to a point south of Elbert. It is not exposed 
north of the creek, although the Myalina bed is definitely present. 
Two miles east of Elbert the Sedwick again becomes visible and 
can be followed to the west for three miles to a point south of 
Leopard Creek. For the next four miles north and northeast to 
a bluff on the west bank of the Brazos, little is seen of the Sedwick 
(now a calcareous sandstone), for a curious reason. A local 
rancher, now deceased, had apparently become deranged from 
his services in the First World War, and seems to have spent 
most of the remainder of his life building beautiful stone walls 
(which have no obvious function) and appears to have incorpo- 
rated in them nearly all sandstones visible in the area. 

The Sedwick appears at the base of the bluff mentioned above, 
and then disappears into the Brazos bottoms. A mile to the 
north, somewhat over a mile below the Spring Creek settlement, 
the Sedwick is seen emerging along a low bluff. From this point 
it runs eastward and northward, crossing Spring Creek and then 
following the north side of Bitter Creek. This is farming country, 
but the general course of the Sedwick can be followed from 
slabs of calcareous sandstones seen here and there in the fields 
and field margins. South of Bitter Creek are low hills, capped 
by sandstones that are obviously Sedwick outliers. More im- 
portant, well logs strongly indicate that the sandstones capping 
the hills west of Padgett, several miles to the south, are also 
Sedwick outliers. 

The Sedwick crosses Bitter Creek about four miles east-north- 
east of Spring Creek settlement and then turns south to become 
clearly visible in slopes lying along the Olney-Spring Creek high- 
way. Farther east the country is quite flat, exposures are rare, 
and were it not for the aid of well logs it would have been 
extremely difficult to follow this bed. The course is slighdy north 
of east, into the northwestern end of the Salt Creek drainage, to a 
point at the west end of the settled Olney area, then north past 
the Lutheran church into Archer County. The course now runs 
north along the west side of a narrow valley which is running 
northward toward the Little Wichita River. East of this valley 
there develops a large outlier bounded (except to the south) 
by well-developed bluffs. The main outcrop follows the valley 
northward to about four miles north of the Young-Archer County 
line, then turns southwest, circling most of the headwaters of 



18 BREVIORA No. 427 

Mesquite Creek and the two Olney reservoirs. Following down 
the west side of these reservoirs, the outcrop continues north close 
to the paved north-south road (farm road 2178) for two and 
one-half miles, then turns east along the low divide between 
Mesquite Creek and the South Fork of the Little Wichita River 
to the region of their junction. Here the outcrop is nearly lost 
in the alluvium, but having crossed Cottonwood Creek, it runs 
southeastward east of that creek ( with outliers to the south ) . 
South of Bobcat Bluff the outcrop swings east and north to the 
region of the former settlement of Anarene. We find here the 
watershed between the West Fork of the Trinitv to the south and 
creeks tending north to the Little Wichita. The divide is marked 
by a west-east line of hills, and a long series of Sedwick outliers 
runs eastward along them to ( and a bit beyond ) the Archer-Clay 
County line. From Anarene the main outcrop (poorly indicated 
for some distance) runs northeastward down the west side of 
Onion Creek. The northern dip of the Sedwick and the gentle 
gradient of the creeks running north to the Little Wichita are 
almost equivalent, and the course of the Sedwick to the east, 
all the way to Montague County, is a complicated one, the 
outcrop dipping to the north in each creek valley, and returning 
south between creeks. The outcrop follows Onion Creek north 
to a point four miles southeast of Archer City, then retreats 
southeast for three and one-half miles, onlv to turn north aeain, 
to follow Little Onion Creek to within a mile of the Archer City- 
Windthorst highway. After a short retreat to the south, it again 
advances northward down the valley of West Little Postoak 
Creek to a Doint north of the highway. It then turns south, 
circling the Windthorst hill, and then (with faint outcrops for 
the most part) follows a tortuous course — for a short distance 
north down a tributary' of East Little Postoak Creek, and, further 
to the east, a mile or more down the valley of that creek. East 
of Windthorst I find the west termination of McGowen's trace 
of his sandstone PI, and his line is thus that of the Sedwick east 
of here. 

The Sedwick sandstone now travels southeastward for half a 
dozen miles, with a major outlier to the south, paralleling the 
course of East Little Postoak Creek upward to its headwaters. 
Turning east, it dips slis^htlv into the headwaters of Deer Creek, 
and then runs eastward to the East Fork of the Little Wichita. 
Here it performs a complicated course. The Sedwick Sandstone 
runs north some miles down the west bank of the fork, then 



1974 PERMIAN WICHITA REDBEDS 19 

turns back west up Joy Creek past the settlement of that name; 
then back down the valley of the Fork five more miles, and up 
a western tributary to Midway School. Finally, after continuing 
obscurely some distance farther down the west side of the Fork, 
it turns southeast and ascends the east side of the East Fork 
Valley for some eight miles, leaving to the west a substantial 
outlier in the region of Friendship cemetery. From a point 
about two and one-half miles northwest of Vashti, it turns 
northward a short distance down Smith Creek, and then east 
across the Clay-Montague County line. The main line of out- 
crop now extends eastward across the headwaters of Belknap 
Creek, a southern tributary of the Red River, dipping down to 
the north along this creek and several of its tributaries before 
reaching the cover of the Cretaceous about five miles north of 
Bowie. 

Coleman Junction Limestone 

Capping the Putnam Formation and underlying the Admiral, 
Coleman Junction Limestone is shown with a considerable degree 
of accuracy on the geological map of Throckmorton County 
(Hornberger, 1937), running north-northeast from a point a 
short distance east of Throckmorton City to cross the Brazos 
west of Spring Creek settlement a few miles south of the Baylor 
County boundary. North of the river the Coleman Junction 
runs eastward, gradually rising in elevation, barely enters Young 
County at its northwest corner, and then continues northeast 
into Archer County rising gently as it goes, crossing Spring Creek 
and the headwaters of Bitter Creek to attain the level of the 
plateau east of Megargel, and, turning north, is present on east- 
ward-facing bluffs about five miles east of Megargel (in an oil 
field that was highly important in the shallow oil days). The 
Coleman Junction has long been known to extend this far north 
and, as noted above, Timms in 1928 attempted to sleuth out 
the general continuation of this unit north, east and north to 
the Red River (cf. Sellards, 1933: fig. 11). Although this was 
hastily done, detailed tracing shows that the line he plotted was 
essentially correct. A sandy lime, turning gradually into sand- 
stone, continues northeastward from this point, high up on the 
west slopes of the valley of the South Fork of the Little Wichita 
River, but gradually descending toward the left bank of the 
South Fork, to reach after 14 miles the west side of the fork 
about two and one-half miles west of Archer City, at the June- 



20 BREvioRA No. 427 

tion of state highway 25 and farm road 210. The outcrop turns 
west and then disappears into the alluvium of the Middle Fork. 
From this point east and northeast the line of the Coleman 
Junction equivalent, as proved by well logs, follows the valley 
of the Little Wichita east and northeast for more than 20 miles, 
to the one-time settlement of Halsell, in Clay County. It is 
possible that in part some of the lowest sandstones north of the 
river are at the Coleman Junction level; on the other hand, 
well logs prove the existence of a number of outliers of this 
sandstone to the south of the main "line of march," extending 
to the neighborhood of Archer City and to high buttes south- 
west of that town; further outliers are present south of the 
river west of Scotland. 

At Halsell, exposures now concealed under the waters of Lake 
Arrowhead show the Coleman Junction equivalent to reappear 
on the east bank of the Little Wichita and run southwest, rising 
gently, for several miles. Emerging above the lake level, it 
swings east, along slopes following the north side of the Deer 
Creek valley which develop into good bluffs north of Deer Creek 
settlement. There I find the western end of McGowen's tracing 
of his sandstone P4, which is thus the Coleman Junction equiva- 
lent. Three miles west of Midway School the outcrop reaches 
a high point at the Myers triangulation marker and enters the 
drainage of the East Fork of the Little Wichita. The Coleman 
Junction now follows down the west side of this valley in an 
irregular northeasterly direction for about nine miles to a point 
opposite Kola siding on the Fort Worth and Denver railroad, 
and about six miles northeast of Blue Grove. From this point 
the main line of Coleman Junction obviously turns east^vard 
past Kola switch and on to the bluffs three miles north of 
Bellevue and two to three miles west of the Clav-Montaffue 
County line. However, the northward dip of the Coleman Junc- 
tion and the gradient of the East Fork are almost identical. In 
consequence the Coleman Junction equivalent extends north- 
ward in a complicated fashion down the vallev of the East Fork 
and an eastern branch of this fork extends as far north as Dick- 
worsham switch. This was obviously mapped competently by 
McGowen and I have not retraced this area. 

At the bluffs north of Bellevue the Coleman Junction leaves 
the East Fork drainas^e for that of Belknap Creek and turns 
northward, gradually descending the western slopes of that valley 
into western Montague County (with a number of outliers to 



1974 PERMIAN WICHITA REDBEDS 21 

the east) and finally, about three miles east of Ringgold, dis- 
appears into the Belknap Creek alluvium and perhaps reaches 
the Red River, only about two miles to the north. 

I have done little work east of Belknap Creek. North of a 
west-east line running past Belcherville and Nocona, bounded 
on the east by the Cretaceous and north by the Red River, is 
a triangular area which McGowen, I am told, found difficult 
to interpret and which I, studying it in more superficial fashion, 
found equally puzzling. A sandstone running eastward along 
the line mentioned is essentially equivalent to the Coleman 
Junction, and hence all of the area under consideration is pre- 
sumably as high as the Admiral Formation, lying above the 
Coleman Junction, and McGowen found here several sandstone 
beds suggesting to him, I am told, that we are here dealing with 
a deltaic condition. On the other hand, Frank Gouin has pointed 
out to me that in the region of Lake Nocona there is a well- 
developed anticline, presumably connected with the Muenster 
arch, which brings relativelv low strata to the surface. On the 
map I have merely indicated the lowest sandstones, which may 
be roughly Coleman Junction equivalents. 

Elm Creek Limestone 

The top member of the Admiral Formation, Elm Creek Lime- 
stone, appears on the 1937 map of Throckmorton County, 
running north-northeast from the neighborhood of Throckmorton 
to the Baylor County line not far west of the Brazos. This 
limestone has not previously been mapped further north. Enter- 
ing Baylor County, this limestone is present in a river bluff across 
the river from Round Timber settlement, and is visible in a 
similar bluff east of the river near Round Timber. In between, 
however, the limestone follows a verv circuitons course. It turns 
westward, gradually descending in elevation along the branches 
of WafTon Creek, and finnllv reaches t^e brpid aHuvial valley 
of the Brazos River at the foot of a bhiff phont two miles north- 
west of Round Timber. Across the river, at t^e month of a small 
creek two miles north of Round Timber, t^e l^mes+^one is seen 
on the north bank of the "Rrazos. The co-'T'^f'^' fmr^-i this point 
north and east toward Westover is flat anrt-Vnltnr-^l land, but 
occasional exposures, mainlv in his^hwav di+r^ps ^how t^e Elm 
Creek to follow a circular course, abon^ t^'^o miVs no^th from 
the river, then abont three mi^es east an-^ i-^^-n V»orV southwest 
toward Round Timber — the limestone p-pininqr some elevation 



22 BREvioRA No. 427 

and becoming more readily traceable in this last part of its 
circuit. 

For several miles east of Round Timber the ground is covered 
by river sands and the Elm Creek Limestone is not visible. 
Beyond this sandy area, however, the limestone can be followed 
(although with some difficulty) northward a bit west of the 
Bavlor-Archer Countv line to reach the west side of Briar Creek, 
about four miles northeast of Westover and just west of the 
county line. From here the limestone runs (rather obscurely) 
northeast, west of Briar Creek and then, a mile or so north of 
the Seymour-Archer City highway, turns west and southwest 
into the valley of Godwin Creek. Here the situation is a con- 
fusing one. The Elm Creek is here a double limestone, and the 
dip of the beds is almost exactly equivalent of the slope down- 
ward to Godwin Creek, so that the two beds, prominently ex- 
posed, form a confusing pattern. The two beds gradually reach 
the creek level about four miles southwest of their first appear- 
ance in the eastern slopes, and then run north, poorly exposed, 
to cross the Little Wichita River above its junction with Godwin 
Creek. North of the river the limestone is better exposed, and 
gradually ascends the slopes, and crosses Slippery- Creek about 
five miles south of Dundee. 

A mile or so east of this creek the limestone disappears and 
(contrary to the usual condition in the Wichita beds) has no 
immediate sandstone continuation. However, well logs clearly 
show that the bed continues east at the foot of the bluffs south 
of Black Flat. East of that settlement the stratum, as shown by 
the subsurface, is continued along the north side of the valley 
of Plum Creek (locally termed Rattlesnake Canyon). However, 
beyond this point, five miles south of Mankins, the bed dis- 
appears into the flat prairies of the Holliday Creek valley and 
for the next six miles can only be traced by well logs, until a 
sandstone at an appropriate elevation appears in the Hull-Silk 
oilfield three miles south of Holliday. This runs eastward for 
five miles, forms a conspicuous bluff, and then turns north to 
disappear into the Holliday Creek alluvium. 

Beyond this point the main outcrop is to be found only north 
of Holliday Creek and, farther on, north of the Big Wichita 
River. However, to the northeast there is a verv extensive series 
of outliers, covering much of northern Clay County. Along the 
divide between the Big ^Vichita and Little Wichita rivers is a 
scattered series of outliers, with elevations somewhat o\'er 1,000 



1974 PERMIAN WICHITA REDBEDS 23 

feet, from the northeast corner of Archer County and the south- 
east corner of Wichita County into the western margin of Clay 
County, just east of the Wichita Falls-Henrietta highway and 
railroad, where the sandstone is present on a low hill at about 
1,030 feet. 

This marks the beginning of a large series of outliers covering 
much of northern Clay County. The beds here are much affected 
by the Electra arch structure, but with one conspicuous excep- 
tion (mentioned later) this structure had become inactive by 
the time of deposition of the Elm Creek equivalent, and the 
beds are almost horizontal, lacking the northern dip seen farther 
south; for the most part the sandstones, which I believe equiva- 
lent to the Elm Creek, average about 950 feet above sea level. 
Except along the Big Wichita River there are few bluffs, and 
exposures are far from continuous along the gently rounded 
hills of the region. The major outlier is one covering the higher 
ground extending northeastward past Dean, Petrolia, and Byers. 
From the southwest corner, at the county line, its borders can be 
followed northward and then eastward around the vallev of Duck 
Creek, eastward and then northwestward to the region of Dean, 
following the upper slopes of the valley of Turkey Creek. After 
running eastward for nearly ten miles, the outcrop turns north- 
west, to circle about the Petrolia oilfield just southeast of that 
town. The outcrop runs eastward again for four miles before 
turning northward again, to run along the upper slopes of small 
creeks running eastward into the Red River. There are further 
small outliers along the high ground east of Petrolia, the last of 
this series only a short distance west of the Stanfield community. 
The east side of the main outlier can be traced as far north as 
Byers. The bed, however, appears to continue about two miles 
north of this town, and then swings sharply southwestward, east 
of the Big Wichita River. Exposures generally close to the 950- 
foot level can be followed along this course for about 14 miles, 
to a point two and one-half miles NNW of Dean. Here the 
supposed Elm Creek Sandstone equivalent, as well as beds above 
and below, are turned up almost vertically, turn sharply to the 
northwest and disappear into the Big Wichita alluvium. Subsur- 
face maps show the presence here of a marked syncline, pre- 
sumably related to the Electra arch structure but representing 
an "adjustment" that took place at a much later date than 
formation of the arch structure. Two miles southwest of this 
area, the presumed Elm Creek Sandstone appears again east of 



24 BREvioRA No. 427 

the Big Wichita and, running south close to the county line, 
reaches the hill mentioned above where the circuit of this major 
outlier was begun. 

The main outcrop of the Elm Creek member, as determined 
by well logs, runs northeastward to Wichita Falls north of Holli- 
day Creek, but is visible only in a few places north of Lake 
Wichita and south of Allendale. Returning westward south of the 
Big Wichita, it is well exposed for most of the way west for ten 
miles, when it disappears into the river alluvium. East of Iowa 
Park it appears north of the river, but there are only occasional 
exposures to plot its course eastward, south of Sheppard Air 
Force Base and the municipal airport, then on eastward north 
of the Big Wichita, past Friberg School and onward past Thorn- 
berry in Clay County to a point south of Charlie. East of this 
point the sequence is interrupted by the course of a former 
channel of the Red River but farther to the east, between the 
Red River and the Big Wichita, Pumpkin Ridge forms a con- 
spicuous outlier. Excellent subsurface logs are present for this 
northernmost part of Clay County, and it is clear that the Elm 
Creek Sandstone turns northward, west of the old river channel 
and then west along the Red Ri\^er bluffs (where possible ex- 
posures are largely covered by soil ) . Coming west into Wichita 
County, this member dips a bit southward into the valley of 
Gilbert Creek and a southern branch of this creek, and then 
vanishes into the Red River bottoms. 

Bead Mountain Limestone 

Bead Mountain Limestone, forming the boundary, has long 
been known to run northeast across Baylor County, and part 
of its course is shown on the 1937 cooperative map of that 
county (Garrett, 1937) and on the similar map of Wichita 
County. Locally it has been termed the Rendham Limestone 
in Baylor Countv and, farther north, the Beaverburk Limestone. 
In contrast to all lower members, it can be traced as a limestone 
all the way to the Red River. In southern Baylor County, it 
crosses the Brazos River about eight miles south of Seymour 
and, rising to the east, crosses Deep Creek and then forms the 
summit of east-facing bluffs as it runs northward on the west 
side of the Godwin Creek \'allev east of the former Endand 
settlement and the England cemetery. It crosses Daggett Creek 
near its head and then swings eastward for some miles (not 



1974 PERMIAN WICHITA REDBEDS 25 

clearly seen) and becomes exposed in bluffs south of the Little 
Wichita River. Turning west, it descends to cross the Little 
Wichita as a limestone ledge about two miles east of Fulda 
station on the Wichita Valley Railroad. Turning eastward it 
can be readily followed for some miles and then, more obscurely, 
it can be seen to cross the Wichita Falls-Seymour railroad and 
highway just east of the Baylor-Archer County line. It now 
turns northward, presently forming a conspicuous bluff which, in 
an outlier, forms the southern margin of the dam of the Diversion 
Reservoir on the Big Wichita River. The limestone turns west 
up the south side of the river, and, since the dip of the beds 
and the slope of southern tributaries of the river are almost 
identical, has an intricate pattern. The outcrop runs southward 
up the valley to two small creeks west of the dam and then, 
west of the county line, strikes the valley of Brushy Creek up 
which it runs almost to the height of land and the Wichita Falls- 
Seymour railroad and highway. It then descends again north to 
the river bluffs, but three miles farther west encounters Boggy 
Creek, up which the Bead Mountain extends for about two and 
one-half miles. Beyond Boggy Creek the limestone reaches the 
river level about a mile west of the bridge leading from Fulda 
to "Sweetly Cruz" camp. North of the river the limestone 
descends to the Diversion Lake dam, keeping (as would be 
expected) close to the lake level. Below the dam the Bead 
Mountain runs to the northeast (Fischer, 1937) along the bluffs 
north of the Big Wichita, for some six miles, then turns west 
to descend into the Beaver Creek vaUey, crossing that creek 
about two miles east of the Wilbarger County line. Its course 
from this point east up onto and along the ridge north of 
Beaver Creek and the Big Wichita, and then back south of 
Beaver Creek, to a point southeast of Fowlkes Station on the 
Fort Worth and Denver railroad, is shown on the 1937 coopera- 
tive map of Wichita County. Until this present study it was 
unknown beyond a point north of Beaver Creek about six miles 
west of Iowa Park. I have, however, been able to trace it north 
to the Red River. In contrast to its strength farther west, the 
Bead Mountain here is thin and sandy in nature. The country 
between this point and the Red River is flat, with few exposures, 
but through occasional small exposures, mainly in road cuts, I 
have been able to plot its general course, northward and then 
eastward around the headwaters of North Buffalo Creek, Lost 
Creek and Stevens Creek, then over a low divide to follow the 



26 BREvioRA No. 427 

north side of the Gilbert Creek valley northeast nearly to Burk- 
burnett. The deeper beds here are much disturbed in relation 
to the Electra arch, but this structure appears to have become 
inacti\'e by the time of deposition of the Bead Mountain, and 
the surface beds here are nearly horizontal. For a short distance, 
near Burkburnett, no exposures of the Bead Mountain Limestone 
are seen, but turning west, it is occasionally visible in the slopes 
south of Wildhorse Creek, which it crosses about two miles 
northeast of Clara. It then attains the south bluff of the Red 
River, where it is clearly visible in the cuts of two roads which 
descend to the river bottoms northeast of Clara. It descends to 
the west, and reaches the level of the Red River alluvium north 
and a short distance west of Clara. 

Leuders Limestone 

The Leuders, now generally regarded as a formation, has 
long been recognized as the top of the Wichita beds, separating 
them from the Clear Fork. I have not studied the Leuders in 
detail. Several members are shown in the 1937 cooperative map 
of Bavlor County, crossing the Brazos in the "canyon" of that 
ri\'er below Seymour and running north past Mavbelle and the 
Kemp Lake dam. I do not 1 now of any detailed mapping of 
the Leuders in Wilbarger County; this limestone senes crosses 
Beaver Creek in the central part of the county and then, as 
stated by Wrather (1917) trends northeast toward Harrold. It 
appears to be represented by sandy lim.estones farther northeast, 
along the lower course of China Creek, toward the Red River. 

REFERENCES CITED 

Adams, G. I. 1903. Strati.^aphic relations of the Red Beds to the Carbon- 
iferous and Permian in northern Texas. Bull. Geol. Soc. Amer., 14: 191- 
200. 

Armstrong, J. M. 1937. Geologic map of Jack County, Texas, revised. Univ. 
Texas, Bur. Econ. Geol. 

Barnes, V. 1967. Geologic atlas of Texas, Sherman sheet, Univ. Texas, 
Bur. Econ. Geol. 

Cheney, M. G. 1940. Geology of north-central Texas. Bull. Amer. Assoc. 
Petrol. Geol., 24: 65-118. 

Cummins, W. F. 1891. Report on the geology of northwestern Texas. 2nd 
Ann. Rept. Geol. Surv. Texas: 359-552. 

. 1893. Notes on the geology of northwest Texas. 4th Ann. 

Rept. Geol. Surv. Texas: 177-238. 



1974 PERMIAN WICHITA REDBEDS 27 
1897. Texas Permian. Trans. Texas Acad. Sci., 2: 93-98. 



Fischer, R. W. 1937. Geologic map of Wichita County, Texas (revised) . 

Univ. Texas, Bur. Econ. Geol. 
Galloway, W. E., and L. F. Brown, Jr. 1972. Depositional systems and 

shelf-slope relationships in Upper Pennsylvanian rocks, north-central 

Texas. Rept. Invest. No. 75, Univ. Texas Bur. Econ. Geol., 62 pp. 
Garrett, M. M., A. M. Lloyd and G. E. Laskey. 1937. Geologic map of 

Baylor County, Texas, revised. Univ. Texas, Bur. Econ. Geol. 
Gordon, C. H. 1913. Geology and underground waters of the Wichita 

region, north-central Texas. U.S. Geol. Surv., Water-Supply Pap., 317: 

1-88. 
Gordon, C. H., G. H. Girty and D. White. 1911. The Wichita formation 

of northern Texas. Jour. Geol., 19: 110-134. 
Hornberger, J., Jr. 1937. Geologic map of Throckmorton County, Texas, 

revised. Univ. Texas, Bur. Econ. Geol. 
Hubbard, W. E., and W. C. Thompson. 1926. The geology and oil fields 

of Archer County, Texas. Bull. Amer. Assoc. Petrol. Geol., 10: 457-481. 
Lee, W., C. O. Nickell, J. S. Williams, and L. G. Henbest. 1938. Strati- 
graphic and paleontologic studies of the Pennsylvanian and Permian 

rocks in north-central Texas. Publ. Univ. Texas, No. 3801: 1-252. 
Moore, R. C. 1949. Rocks of Permian (?) age in the Colorado River 

valley, north-central Texas. U.S. Geol. Surv., Oil and Gas Invest., 

Prelim. Map 80, 2 sheets. 
Plummer, F. B., and F. B. Fuqua. 1937. Geologic map of Young County, 

Texas, revised. Ufiiv. Texas, Bur. Econ. Geol. 
, AND R. C. Moore. 1922. Stratigraphy of the Pennsylvanian 

formations of north-central Texas. Bull. Univ. Texas, No. 2132: 1-237. 
Romer, A. S. 1958. The Texas Permian Redbeds and their vertebrate 

fauna. In Studies on Fossil Vertebrates, Essays presented to D. M. S. 

Watson (T. S. Westoll, ed.) . London: Athlone Press, pp. 157-179. 
Sellards, E. H. 1933. The pre-Paleozoic and Paleozoic systems in Texas. 

In The Geology of Texas. Vol. 1 (Stratigraphy) , pt. 1. Bull. Univ. 

Texas, No. 3232: 15-238. 
TiMMS, V. E. 1928. Cisco-Wichita contact in northern Texas and southern 

Oklahoma. Map, Roxana Petroleum Corporation. 
Wrather, W. E. 1917. Notes on the Texas Permian. Bull. Southwestern 

Assoc. Petrol. Geol., 1: 93-106. 



28 



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1974 



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Cambridge, Mass. 27 November 1974 Number 428 

A DESCRIPTION OF THE VERTEBRAL COLUMN 

OF ERYOPS BASED ON THE NOTES AND 

DRAWINGS OF A. S. ROMER 

James M. Moulton^ 

Abstract. This paper includes an illustrated description of the vertebral 
column and ribs of Eryops megacephalus Cope, based principally on notes 
and drawings prepared by A. S. Romer. The paper examines closely re- 
gional variation in the column. The descriptions, originally written of the 
Eryops now mounted in the Museum of Comparative Zoology (MCZ 1539) , 
are amplified by reference to other specimens. The paper includes data on 
growth stages and regional variation in the vertebral column and ribs, which 
will be useful in interpretation of Eryops postcranial remains. 

INTRODUCTION 

This publication was to have been based on collaborative 
work with Alfred S. Romer, but his untimely death on Novem- 
ber 5, 1973 prevented this. Fortunately, his notes and drawings 
on the postcranial anatomy of Eryops have been available to me 
and are here incorporated; his handwritten descriptive working 
notes are only slightly modified. The paper presents a general- 
ized description of the vertebral column of Eryops, and drawings 
of a set of presacral and postsacral ribs. The principal concern 
in preparing this material has been that Professor Romer's ob- 
servations should be available to paleontologists. To Professor 
Romer's observations, I have added others which appear to be 
of interest. 

Gregory (1951, I: 253) called Eryops "the best known" of 
all rhachitomous labrinthodonts ; Williston (1914) called it "the 
most famous' of the Temnospondyli. But despite the detailed 
descriptions of various parts — skull ( Sawin, 1 94 1 ) , teeth ( Stick- 

^Department of Biology, Bowdoin College, Brunswick, Maine 04011. 



2 BREVIORA No. 428 

ler, 1899), forelimb (Miner, 1925), ilio-sacral attachment f Ol- 
son, 1936a) — no account of the vertebral column as a whole 
is available. 

In familiarizing myself with Eryops material, I gratefully 
acknowledge the help of discussions with Ernest E. Williams, 
Nelda Wright, Robert L. Carroll, Thomas S. Parsons, John R. 
Bolt, Keith S. Thomson, Bryan Patterson and Bobb Schaeffer, 
and to Carroll, Patterson, Wilhams and Wright I extend thanks 
for critical reading of all or of large portions of my manuscript. 
I appreciate the opportunity to study specimens in the following 
institutions : the Redpath Museum of McGill University with Dr. 
Carroll, the Cleveland Museum of Natural History (CMNH) 
through David H. Dunkle, the Field Museum of Natural History 
(FMNH) through Dr. Bolt, the Peabody Museum of Yale Uni- 
versity through Dr. Thomson, the American Museum of Natural 
History (AMNH) ) through Eugene S. Gaffney, and the Pratt 
Museum of Amherst College through Walter P. Coombs; and 
I was aided by valued correspondence with several of those 
mentioned above and also with Robert E. DeMar, Everett C. 
Olson, A. L. Panchen, F. R. Parrington and Peter P. \"aughn. 
A loan of Eryops avinoffi material from the Clex^land Museum 
is gratefully acknowledged. 

The staff of the Museum of Comparative Zoology, and espe- 
cially Professors A. W. Crompton and Parish Jenkins, Jr., Direc- 
tor and Associate Curator of Vertebrate Paleontology, have been 
very generous with their hospitality and have made the Museum 
a most rewarding place to work during spring term of 1973-74. 
I am indebted for travel and research funds to Bowdoin College. 

Eryops material has been described from the Carboniferous 
and Permian of an area extending from New Mexico to Prince 
Edward Island fLangston, 1953, 1963; Olson and Vaughn, 
1970), the bulk of it from the lower Permian of Texas where 
it is the common large form (Romer, 1958). Both the geological 
range occupied by Eryops and the length of time it survi\'ed are 
grounds for suspecting that more than one Eryops species existed 
(Williston, 1914; Romer, 1943, 1947, 1952). But in the ab- 
sence of a sound anatomical basis for separating species (Romer, 
1947, 1952; E. C. Olson, personal communication), the bulk 
of Eryops material from the Permian is now generally assigned 
to Eryops megacephalus Cope, 1877. Appreciation of the extent 
of speciation in Eryops must await a distinction between specific 
differences and those due to growth and accidents of preserva- 



1974 VERTEBRAL COLUMN OF ERYOPS 3 

tion. Recognized as a distinct species, however, is Eryops avinoffi 
(Romer) from the Pennsylvanian of West Virginia and lower 
Permian of Pennsylvanian (Romer, 1952; Vaughn, 1958). 
Photographs of its dorsal vertebrae have been published (Mur- 
phy, 1971). 

It is to Cope then that we are indebted for the original de- 
scription of Eryops from Texas Permian material collected by 
Jacob Boll, his friend and collector (Cope, 1877; Osbom, 1931 : 
486), and himself a recognized scientist (see e.g. Broili, 1899: 
61) and practicing geologist. Bom in Canton Aargau, Switzer- 
land on May 29, 1828, Boll died alone of appendicitis in a tent 
on the Pease River near its confluence with the Red River in 
Texas on September 29, 1880 (A. S. Romer, personal com- 
munication), lamented by his friend Cope (1884). Eryops 
material was given a prominent place in Cope's collection (Os- 
born, 1931: frontispiece; 587) and figured frequently in his 
publications. Cope's paleontological collections, purchased for 
the American Museum of Natural History {idem, Chapter 6), 
included materials Boll had collected. One specimen, AMNH 
4183, from which I believe Cope's most frequently reproduced 
figures of vertebrae were drawn (see, for example, Cope and 
Matthew, 1915), is still accompanied by Boll's penciled, signed 
field label dated 1-12-80 from the North Fork of the Little 
Wichita River, which, together with the Big Wichita, Boll ex- 
plored scientifically for over six months from December, 1879 
(Boll, 1880). While studying this material in the American 
Museum collections on March 28, 1974, I happened to turn 
over the old field label, and there was a penciled poem, also 
signed 'Boll', which read as follows: 

"Nun wirst du mit noch manchen andern 
Zum Sitze des Professors wandern. 
Geistreich denkend wird er dich erwecken, 
Aus deinen Triimmem dich zusammensetzen. 
Der Nachwelt wird er dann erzaehlen, 
Wie du gebaut in deinen Zahnen, 
Wie du gelebt und wie verschwunden, 
Benennen dich und was gefunden." 

For help in transcription, I am indebted to B. Werscheck of the 
American Museum of Natural History. 

Cope's publications dealing significantly with the vertebral 
column of Eryops appeared in the years 1877, 1880 (a,b), 1881, 
1882, 1884, and 1890, a number of them repeating the same 



4 ' BREvioRA No. 428 

left lateral and ventral views of portions of the vertebral column 
which first appeared in 1880 (Cope, 1880b); some of Cope's 
discussions of rhachitomous vertebrae (1878a,b; 1897; 1898) 
omitted them, but they finally appeared in Cope and Matthew 
(1915). Later diagrams of Eryops vertebrae or of generalized 
rhachitomous vertebrae, often drawn to emphasize particular 
points, are seldom more convincing than those Cope drew 'from 
life'. 

Cope (1880a,b; 1881), Broili (1899), Branson (1905), Case 
(1911, 1915), WiUiston (1918), Watson (1919), Olson 
(1936b), Rockwell, Evans and Pheasant (1938), Romer (1947, 
1966), Gregory (1951), Panchen (1967, Parrington (1967), 
Thomson and Bossy (1970), and Williams (1959) collectively 
provide a description of the Eryops vertebral column and its 
evolution, often with special attention to typical dorsal vertebrae. 
The papers of Cope (1880b) and Case (1911) provide the most 
complete accounts. Further, a paper on another rhachitome, 
Edops (Romer and Witter, 1942), makes several points about 
the vertebrae of Eryops and provides a measure of differentiation 
within the rhachitomes. A photograph of Eryops caudal verte- 
brae from the MCZ mount (MCZ 1539) has been published 
(Romer and Witter, 1941) with a description of dermal scales 
(see also Williston, 1915); caudal vertebrae have also been 
illustrated by Cope (1890). Diagrams of Eryops and other 
rhachitomous vertebrae are generally shown in lateral view; it 
is not easy to comprehend the three-dimensional form without 
the actual specimen in hand. The deficiency of anterior and 
posterior views is corrected by several of Romer's figures in the 
present paper. Anterior views of dorsal vertebrae are provided 
by Broili (1899) and Rockwell et al (1938). Branson (1905) 
and Cope (Cope and Matthew, 1915) show the atlas in anterior 
view, while Cope (idem) and Olson (1936b) show side views 
of atlas and axis, articulated and disarticulated respectively; 
Cope [idem) shows a somewhat distorted atlas (AMNH 4183) 
articulated with the axis in anterior view. Photographs of 
mounted Eryops skeletons have been published (Miner, 1926; 
Romer, 1 943 ) , as well as drawings of the entire skeleton ( Case, 
1911; Gregory, 1951). 

An illustrated description of the whole vertebral column and 
ribs had long been planned by Romer (1943, 1947, 1958). His 
drawings with others showing particular points are here pre- 
sented with a description prepared largely from his handwritten 



1974 



VERTEBRAL COLUMN OF ERYOPS 



5 




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Plate L Mounted skeleton of Eryops, MCZ 1539 (from Roraer, 1943) 
X 1/21. 



notes. Observations on variations in size and form in Eryops 
vertebrae are also included. A future study should focus on 
vertebral growth in Eryops megacephalus, a matter of consider- 
able interest only touched on in the present paper. This paper 
examines variation in structure throughout the vertebral colurnn, 
and reconstructs the probable structure in life of the vertebral 
column of Eryops from the dissociated jumble of neural arches, 
pleuro- and intercentra to which the vertebral column of Eryops 
and other rhachitomes is often reduced in the fossil state. 

The Eryops mount in the Museum of Comparative Zoology 
(Plate I), the "most perfect (skeleton) yet discovered" (Romer, 
1943), is a not quite full-grown animal (A. S. Romer, personal 
communication). Vertebrae of larger size and more massive 
construction than those in the mount are not uncommon in the 
collections I have studied. The MCZ mount is however com- 
parable in size to similar mounts in the Cleveland, Field, Pea- 
body, American and Pratt Museums collected over a considerable 
span of years, suggesting that full-grown (or larger species) of 
Eryops for some reason lent themselves less well to preservation 
or were rarer than smaller animals. The specimen in the Pratt 
Museum, from Geraldine, Texas, is probably the youngest of the 
mounts studied; it is somewhat smaller than the MCZ mount 
which measures over the tops of the neural spines 187.5 cm 
muzzle to tail tip, with a presacral vertebral column of 71.9 cm 
and a postsacral length of 80.6 cm. The skull measures 35 cm. 

From well-preserved Eryops material such as that which fur- 
nished the mounts for the MCZ and Pratt Museum, Romer 
(personal communication) was able to "make outlines of the 
whole set of vertebrae, clear to the tip of the tail, and each rib"; 



6 BREVIORA No. 428 

drawings from those outlines illustrate this article. Complete 
tails and even complete presacral series of Eryops vertebrae have 
not been common finds, and understandably controversy has 
arisen over tail lengths and vertebral numbers. The MCZ mount 
is taken to be correct until better information is available; it 
displays 22 presacral vertebrae, two less than the primitive num- 
ber (Romer, 1947; Vaughn, 1971), and 37 postsacral vertebrae, 
a total, with the single sacral, of 60. The paired proatlas atop 
the bisected atlas is well shown in its correct relationships in the 
Field and Pratt mounts ( Fig. 1 ) . Presacral-postsacral counts of 
five other Eryops mounts are: 22 — 44, 21 —51, 22 — 30, 22 
— incomplete postsacral series, and 22 — 46. 

With Case (1915) we are inclined to believe that the bifur- 
cated caudal spines in Eryops provided dorsal accommodation 
for tendons, which in primitive forms are the chief support of 
the axial column (Olson, 1936b) ; the Eryops arrangement sug- 
gests a tail of reasonable length which may have been held off 
the ground. Tail length in Eryops should be resolved because 
it is of significance in understanding locomotion. Former esti- 
mates have varied from Cope's of a medium-length tail (1880b) 
to a stump nearly coccygeal (1884), the latter seconded with 
some reservation by Case (1915), to Williston's admission of 
ignorance and his drawing of Eryops with its tail concealed by 
vegetation (Williston, 1914). Romer's orthometric linear unit 
(Panchen, 1966) has not been applied to Eryops in estimating 
a length for the tail. 

The following descriptions unless otherwise stated are based 
on vertebrae in the MCZ and Pratt Museum mounts of Eryops. 

PRESACRAL VERTEBRAE BEHIND THE AXIS 
(DORSAL VERTEBRAE) 

(Figs. 1-4; 9 I; 10; 11; measurements in Table 1) 

Each vertebra consists of four ossifications : neural arch, paired 
pleurocentra behind the neural arch and a single intercentrum 
ahead and below. The neural arch terminates dorsally in a 
neural spine that, for an amphibian, is of considerable height. 
In a mid-dorsal, the height of the spine above a line through the 
center of the zygapophyses is 56 mm, when the vertebral length 
is 35 mm, a ratio of 1.6. Spine height increases to 73 mm in 
the last presacral, and the height-length ratio approaches 2. 
There is a gradual decrease in spine height anteriorly — it being 



1974 



VERTEBRAL COLUMN OF ERYOPS 



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VERTEBRAL COLUMN OF ERYOPS 



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1974 VERTEBRAL COLUMN OF ERYOPS 15 

57 mm in vertebra 5 — and a rather sharp decrease associated 
with transition to the skull, it being 44 mm at the axis. 

In reasonably mature specimens, the tops of the spines become 
expanded, subcircular and rugose; they surely lay in the dermis. 
The appearance in some cases is of dermal ossifications fused to 
the spine tips (Fig. 14 B), but there is no evidence of separate 
ossifications. Expanded spine tips may be lacking in young 
specimens. The width of the spine shaft is about 2/3 of the 
anteroposterior dimension, although sometimes the neural spines 
are considerably more flattened than this. The spines often 
assume a diamond form in cross-section with lateral ridges in 
the upper part which expand into the sides of the dorsal rugosity. 

Minor spines, spurs and flanges are not uncommon on neural 
spines and elsewhere (Fig. 9 I; two spines on a neural spine, 
AMNH 4183 ; spine on transverse process of vertebra 18, AMNH 
4280; flange on spine of postsacral 10, MCZ 1539). Some of 
these may be artifacts of preservation, as is undoubtedly the 
flattening observed in some neural spines. A remarkable flexi- 
bility of Eryops skeletal material either shortly after death be- 
cause of drying cartilage (see p. 22) or changes during preserva- 
tion is suggested by the twisted neural arches and spines one not 
infrequently encounters in collections (Fig. 9 D; sacral vertebra 
of MCZ 2669, for example) . 

The upper part of the neural spine is keeled both anteriorly 
and posteriorly. In the lower part of the spine, the keel bifurcates 
into two divergent ridges which pass into the zygapophyses ven- 
trally. Secondary ridges may be present within the groove en- 
closed by the ridge pairs. Both grooves tend to become reduced 
in depth in very large vertebrae. The anterior groove may extend 
more than halfway up the spine, more so in the anterior part of 
the vertebral column than posteriorly. In the last presacrals, the 
anterior groove is limited to 1 /3 of the spine height and becomes 
relatively shallow. The point of bifurcation of the ridges at the 
top of the grooves is often recognizable in side view by a marked 
angularity in the contour of the spine, and the spine shaft is 
broadest between these points. The posterior groove deepens 
ventraUy into a deep pit between the posterior zygaphophyses. 

The zygaphophyses are of the normal primitive tetrapod type 
and are readily comparable with, for example, those of many 
pelycosaurs in size, contours, inclination and relative position. 
As usual in labyrinthodonts and pelycosaurs, but in contrast to 



16 



BREVIORA 



No. 428 




Figure 9. Based mainly on Eryops MCZ 1539 and 1883, all X .5. (A) 
Atlas and axis with their intercentra, in anterior view, proatlas removed. 

(B) Eryops occipital region, atlas, axis and right proatlas, anterior at top. 

(C) Eryops occipital region from below showing anterior intercentra. (D) 
Eryops axis MCZ 1883, anterior view. (E) Eryops axis MCZ 1883, right 
lateral view, anterior flange reconstructed. (F) Eryops axis MCZ 1883 in 
dorsal view. (G) Eryops atlas and proatlas, left elements from medial side, 

(H) Eryops vertebra 4, posterior (above) and anterior views. (I) Eryops 
vertebra 6, posterior (1.) and anterior views. 



1974 



VERTEBRAL COLUMN OF ERYOPS 



17 




Figure 10. All X .5. (A) Eryops vertebra 13, posterior (1.) showing 
position of notochord and anterior views. (B) Eryops vertebra 13, posterior 
views, with (1.) and without reconstructed cartilages surrounding bony cen- 
tra. (C) Eryops vertebra 21, posterior view. (D) MCZ 1828, left view, show- 
ing matrix (dark stippling) occupying position postulated for cartilage about 
centra of presacral vertebrae. (E) Reconstruction of two dorsal vertebrae 
showing cartilage reconstructed about centra and rib head. (F) Eryops 
vertebrae 23 and 24, right view, showing facets for rib articulation (large 
stippling) . 



18 



BREVIORA 



No. 428 



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1974 VERTEBRAL COLUMN OF ERYOPS 19 

cotylosaurs, the zygaphophyses are situated close together with 
but a short interval between the medial surfaces of the com- 
ponents of each pair. The typical dorsal zygapophyses are tilted 
so that the posterior zygaphophyses face about 45° out from the 
median plane and 45° up from the horizontal plane, and diverge 
30° laterally from the median plane; the anterior ones face 45° 
in, 45° down and diverge 30° laterally. The angles of the zyga- 
pophyses vary somewhat throughout the length of the column, 
the posterior zygapophyses tending to be nearer the horizontal 
and smaller anteriorly than posteriorly. The face of the posterior 
zygapophyses is quite flat throughout, the anterior concave. 

Continuing to consider a mid-dorsal vertebra, below the level 
of the zygapophyses the neural arch divides into two pedicels; 
between them these form a well-defined roof and lateral walls 
for the neural canal, which is subcircular in outline, as the center 
of the floor is unossified. The degree of closure of the pedicels 
below the neural canal, however, is a function of age and size 
or both (Fig. 11). One can demonstrate sacra (MCZ 2604, 
4305) and a caudal vertebra (MCZ 3316, Fig. 11) with a 
completely ossified neural canal, and a whole series of dorsal 
vertebrae in which it is nearly closed ventrally (MCZ 3316, 
Fig. 11). Where the floor is unossified, cartilage probably 
formed a ventral apex to the neural arch between intercentrum 
and pleurocentrum in life. 

Laterally, the surface between the anterior and posterior zyga- 
pophyses is smooth, but there is a depression, usually rather 
shallow, behind and below anterior zygapophysis. At about 
the midpoint of the length of this depression a ridge develops 
that swings down and back into the dorsal edge of the transverse 
process, presumably associated with the passage of a segmental 
blood vessel. 

The anterior and posterior margins of adjacent vertebrae, 
below the zygapophyses, form the posterior and anterior margins 
respectively for the intervertebral gaps that afforded exit for the 
spinal nerves. These margins do not, however, form ventral 
boundaries for the gaps. 

The posterior surface of the neural arch on each side, from 
the level of the neural canal floor down over the pedicel, in- 
cludes a very large unfinished area which faces as much inward 
and downward as backward. It is subquadrate in form, but 
rounded in the dorsolateral margin. This surface corresponds 



20 BREvioRA No. 428 

to that on the anterior surface of the pleurocentrum and is 
articulated with the anterior face of that element, although 
obviously with an intervening thickness of cartilage. The rough- 
ened anterior face of the pedicel, continuous with the posterior 
face at the ventral edge, is much smaller and irregularly shaped. 
The upper portion, adjacent to the spinal canal, is subcircular 
with a pronounced convex mass of bone projecting backward 
and inward. The more ventral portion of this surface slants 
downward and outward, narrowing rapidly, becoming concave 
rather than convex, and twisting so as to face a little inward. 
This surface matches the posterior face of the next anterior 
pleurocentrum to a moderate degree and undoubtedly apposed 
it; there must have been a considerable thickness of cartilage 
between the two. 

The transverse process is rather variably developed. It is 
typically wedge-shaped in section and at the distal articular sur- 
face broad above, narrower below. Typically, the dorsal margin 
arises in a ridge projecting laterally beyond the surface of the 
arch pedicel. It faces backward and downward so that the 
articular surface in a mid-dorsal vertebra faces back about 40° 
and about 30° downward, in anterior vertebrae more directly 
laterally. 

In a mid-dorsal, the articular surface for the rib extends down- 
ward to form the most ventral part of the arch ossified; typical 
anterior vertebrae are similar. Posteriorly the articular area 
becomes reduced to the dorsal part of the articulation. In more 
anterior dorsals, there are two distinct portions : ( 1 ) a broader 
oval dorsal area meeting the tubercle; (2) a thinner ventral 
extension. Posteriorly, the ventral part disappears and the upper 
part becomes thin; anteriorly the upper part remains thick and 
the ventral part tends to thicken as well, until the articular sur- 
face becomes a unit. 

The measurements of Eryops dorsal vertebrae presented in 
Table 1 are based on AMNH 4280, which includes a set of 
dorsal vertebrae to which definite numbers can be assigned, and 
MCZ 1539, the mounted specimen. From the information pro- 
vided by these two specimens, it has been possible to estimate 
the position of isolated Eryops presacral vertebrae through the 
size ranges most abundant in collections I have studied. Meas- 
urements of isolated Eryops vertebrae have been published by 
Cope (1877, 1878a,b) and Case (1911). 



1974 



VERTEBRAL COLUMN OF ERYOPS 



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22 BREVIORA No. 428 

THE INTERCENTRA OF PRESACRAL VERTEBRAE 

(Figs. 1-4; 9 I; 10; 12; 13 A-C) 

The dorsal intercentra are of the usual rhachitomous type, 
being crescents as seen in anterior and posterior view, convex 
side down. They are wedge-shaped in side view, apex upward. 
Concavities on their external surfaces may mark the paths of 
blood vessels. The inferior surfaces tend to descend as flanges 
anteriorly and posteriorly, least so in the posterior dorsals. A flat 
longitudinal ridge tends to develop mid-ventrally, best seen in the 
dorsal region. The surface may be notched posteriorly at the 
area of rib capitulum articulation. This is not well seen in young 
individuals and may be lacking in fairly large animals. It is most 
emphasized anteriorly in the presacral column, and at the sacrum 
(Fig. 12). 

The anterior, posterior and dorsal surfaces are rough and un- 
finished, and presumably were continued in cartilage. The dorsal 
notch is a rounded longitudinal depression, occupied in life by 
the notochord and surrounding tissues. Four hummocks of bone, 
two fore and two aft, are arranged on either side of the depres- 
sion and may represent centers of ossification ( Fig. 1 3 A ) . These 
hummocks show with varying clarity, sometimes are completely 
obscured, and are illustrated as ridges by Broili (1899). Seen in 
side view the anterior pair of hummocks is slightly more ventral 
than the posterior in dorsal intercentra; the posterior hummocks 
are closer to the top of the intercentra. 

Cartilage, with which the intercentrum was continuous, may 
have surrounded the notochord in life (Romer, 1947), but no 
ring intercentra have been found. Coossification of the pleuro- 
centra occurs below the neural canal (Fig. 13 E), above the 
notochord (MCZ 2622 and 1652). Such a coossified piece may 
in turn coossify with the intercentrum to form a type of ring 
centrum in which all three elements are distinguishable (MCZ 
2604 and 2562). A completely coossified vertebra has also been 
studied (FMNH UR745). Such remains are perhaps the best 
evidence of a vertebral column of ossified pieces embedded in a 
matrix of cartilage in Eryops. 

Intercentra that were broken during life are rarely found. Two 
dorsal intercentra have been found (MCZ 2621, 4306; Fig. 13 
B, G), which I think were so broken; a third (MCZ 4305) is 
cracked diagonally on the dorsal surface. Each break is at an 
angle clockwise to the anteroposterior axis (2621, 8°; 4306, 30°; 



1974 



VERTEBRAL COLUMN OF ERYOPS 



23 




Figure 12. The presacral and sacral (23) intercentra of Eryops in ventral 
view, anterior uppermost, X .6. 



24 



BREVIORA 



No. 428 




B 




(^ 










H 



Figure 13. All X .5. (A) Eryops presacral intercentrum showing paired 
protuberances, anterior uppermost. (B) MCZ 2621, presacral intercentrum, 
ventral view, anterior at top, showing inclination of healed break. (C) MCZ 
4306, intercentrum, as in (B) . (D) MCZ 4307, a left pleurocentrum in 
anterior, lateral, posterior and medial views. (E) MCZ 2591, anterior view 
of coossified pleurocentra. (F) MCZ 4325, left and right sacral rib central 
articulations in ventromedial views. (G) MCZ 2085, right sacral rib central 
articulations in ventromedial view. (H) MCZ 2621, right sacral rib central 
articulations in ventromedial views. (I) Sacral vertebra and right sacral rib 
of Eryops, right view, pleurocentra not shown. 



1974 VERTEBRAL COLUMN OF ERYOPS 25 

4305, 30°). That these breaks occurred in younger animals is 
evidenced by the small size of one intercentrum (MCZ 4306) 
and the appearance of extensive growth after healing in the 
other (MCZ 2621). 

A fragment of the atlas intercentrum still clings to the left 
element of the atlas in AMNH 4183 (omitted by Cope and 
Matthew, 1915: pi. 12). 

THE PLEUROCENTRA OF PRESACRAL VERTEBRAE 

(Figs. 1^; 9 I; 10; 13 D, E) 

The pleurocentra are paired ossifications, the centers for which 
are situated dorsal to the notochord rather close to the midline. 
Study of articulations of components of the vertebrae indicate, 
however, that they must have been situated in pleurocentral 
cartilages of much larger size. Such cartilages would have ap- 
peared rhomboidal in side view, their longer sides articulating 
anterodorsally with the arch of the same vertebra, anteroventrally 
with their own intercentrum, posterodorsally with the next pos- 
terior neural arch, and posteroventrally with the next posterior 
intercentrum. 

Their contours indicate that the ossified pleurocentral elements 
came close to the ventral margin of the column but did not reach 
it externally; restoration of the cartilage suggests that the car- 
tilaginous pleiirocentra probably did not gain contact with each 
other ventrally ( Fig. 1 B ) . Dorsally, however, they were ob- 
viously in broad contact beneath the spinal cord; occasional 
coossifications in old specimens would suggest that the cartilages 
may have been continuous below the floor of the neural canal. 
The conjoined elements would have given in end view the ap- 
pearance of an inverted crescent with the two horns closely 
approximated ventrally. The cartilaginous pleurocentra could 
have closely approximated those seen in ossified form in Tri- 
merorhachis. 

' The paired centers of ossification of the pleurocentra appear 
to have been situated far dorsally where there is a globular mass 
of bone from which ossification proceeded slowly toward the 
ventral part of the element. The pleurocentra appear to be 
feebly ossified, and much of their surface area is unfinished in 
aU but very old specimens. The more anterior pleurocentra are 
in general less ossified, and far anterior ones are almost unknown 
(see also Branson, 1905). A fifth pleurocentrum in the MCZ 



26 BREvioRA No. 428 

mount is finished on almost none of its surface, a fourth is a tiny 
nubbin on one side only and coossified with the arch, and there 
are no traces in material known to me of pleurocentra 1 and 2. 

Exceptionally the two pleurocentra may abut medially, as they 
do in sacral vertebrae in two mature specimens (MCZ 2669 and 
4305 ) . There are cases in which the pleurocentrum has coossi- 
fied with the neural arch, as on one side in two different sacra 
(MCZ 4305, 2604), and cases of coossification with the inter- 
centrum behind ( FMNH 60 ) , or at one level with intercentrum 
and at another with neural arch (MCZ 1387), or with both in 
the same vertebra (FMNH UR745). Such cases are suggestive 
of a continuum of cartilage, the vertebral pieces embedded in it, 
similar to what Parrington has proposed. 

The pleurocentra are likely to abut in the caudal region ( MCZ 
1787 and 2634), even to the point of occluding the notochordal 
canal (Fig. 15 F). The anterodorsal face of a pleurocentrum, 
that which articulates with the neural arch of its vertebra, is 
nearly flat and forms essentially a quadrant of a circle with a 
curved margin laterally and ventrally. In life this surface faced 
somewhat up and out as well as anterior and was apposed to 
the neural arch, although separated by at least a film of cartilage 
from it. The posterior surface is irregular, convex above, and 
apposed to but rather far from the anterior margin of the neural 
arch. The medial and posterior surfaces present a continuous, 
rough, curving form. 

The external surface is in great measure finished. It is wedge- 
shaped in external view, narrow above, broadening and then 
tapering below. The margins curve up sharply anteriorly and 
posteriorly so that the pleurocentrum is externally concave in 
section; the curved margins are best defined above. The groove 
between the margins conveyed a spinal nerve. It narrows dor- 
sally and at the very top turns anteriorly above the anterior 
articular surface to blend smoothly into the lower wall of the 
neural canal. The constant mismatch between the large surfaces 
on the neural arches for articulation with pleurocentra and cor- 
responding anterior articular facets of the pleurocentra collected 
at the same time and place is a measure of the extent of cartilage 
beyond the borders of the ossified pleurocentra. 

THE ATLAS-AXIS COMPLEX 
(Figs. 1; 9 A-G; 14; PL I) 

The neural arch of the atlas is highly specialized. The two 



1974 VERTEBRAL COLUMN OF ERYOPS 27 

sides may be separate (MCZ 1883) or coossified (AMNH 4183; 
Case, 1911). In the former case, each side consists of a stout 
pedicel and slender half arch and neural spine directed dorso- 
posteriorly. The pedicel is wedge-shaped with two broad articular 
surfaces, anteroventral and posteroventral. The anterior surface 
is for articulation with an exoccipital; the posterior is finished 
above (MCZ 1883), rough below where it articulated with the 
intercentrum of the axis. Each articular surface is a quadrant 
of a circle with a common straight ventral margin. The posterior 
surface is somewhat concave, not flat as usual. Internally there 
is a well-marked curved area for the side wall of the neural canal. 
At the base of the spine on each side is a flat tubercle, a well- 
defined anterior zygapophysis to seat the proatlas. Each half- 
spine is a thin rod, posteriorly and dorsally directed close to the 
axis spine. A tubercle or slight flange on the lower edge of the 
half -spine rested in life on the corresponding anterior zygapophy- 
sis of the axis. 

The atlas intercentrum, seldom preserved, appears to ossify 
late. That associated with Sawin's (1941) specimen is a very 
flat crescent, with the outline of a slight notochordal space above, 
and the anterior edge with a central depression. There is only 
one pair of mounds, and the back surface is unexceptional. The 
front is subdivided into two articular areas facing rather laterally 
as well as anterodorsally, and obviously covered with much car- 
tilage in life. The intercentra of atlas and axis have no capitular 
facets. 

Each proatlas is a small neural arch, the short neural spine 
slanting back and upwards, its tip being irregularly rugose. At 
its base is an articular facet for the atlas tubercle. The anterior 
limb defines the upper edge of the foramen for the first spinal 
nerve and appears to barely touch the exoccipital region of the 
skull above and lateral to the foramen magnum; there is no 
formed facet. 

There was undoubtedly restricted motion of the head, in the 
absence of a neck ; the atlas-skull joint probably acted as a dorso- 
ventral hinge. 

The axis neural arch is in many respects an ordinary one 
(Fig. 10). The neural spine is however elongated anteroposteri- 
orly. The spine slants backward and then angles up in its longer 
dorsal portion, relative to a plane through the zygapophyses. 
The spine is wedge-shaped in frontal section, and is generally 
thicker posteriorly than anteriorly. There is a variable but gen- 



28 



BREVIORA 



No. 428 










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1974 VERTEBRAL COLUMN OF ERYOPS 29 

erally prominent angle posteriorly, toward which a ridge is di- 
rected on either side from the widest point of the dorsal surface. 
Development at the front of the neural spine is very variable, 
depending in part on preservation. It is likely that a well-devel- 
oped thin flange occurred on the front of the axis spine for a 
median ligament to the occiput. The anterior zygapophyses are 
much reduced to small flattened areas for articulation with the 
arch of the atlas. The pedicel and transverse processes are not 
specialized. The intercentrum of the axis is flat-bottomed, broad, 
and the posterior end has a rounded projecting keel. The axis 
is the most anterior vertebra to bear a rib. Constancy of form 
of the axis spine is illustrated in Figure 14 A. 

VERTEBRA FOUR 

Figs. 1; 9 H; PI. I) 



This vertebra, with its specialized neural spine and anterior 
zygapophyses, makes up for restrictions in movement at the 
occiput. The posterior zygapophyses are normal, but the 
anterior ones are greatly expanded and nearly horizontal, thus 
permitting freedom of motion in the horizontal plane, together 
with some rotation vertically. The spine is much reduced ( Case, 
1911; Romer, 1943), a fact apparently not revealed by Cope's 
material. The spines of vertebrae 3 and 5 are inclined toward 
each other above that of 4; they are therefore distinctive. Their 
neural spines like that of the axis are somewhat elongate antero- 
posteriorly, and their facing edges are thinned, suggesting a spe- 
cial connection taking up the movement between vertebrae 3 
and 4. These features are illustrated in Figure 1. In the Field 
Museum mount the spine of vertebra 4 curves slightly forward. 

THE SACRUM 

(Figs. 4; 10 F; 15 A; 12; 13 F-I) 

The spine of the sacral vertebra is high and slants backward; 
in the MCZ mount the highest spine is that of vertebra 26, three 
behind the sacral (Table 2). The anterior zygapophyses are 
quite large, being the most posterior of an increasing size series. 
The posterior zygapophyses comprise approximately half the area 
of the anterior. The transverse process is enormously developed 
for articulation with the large tuberculum of the sacral rib, and 
the intercentrum bears a large facet for the capitulum. The facet 
may impinge upon the pleurocentrum (Fig. 15 A; FMNH 



30 



BREVIORA 



No. 428 




1974 



VERTEBRAL COLUMN OF ERYOPS 



31 



Table 2. Some measurements of Eryops Anterior Caudal Vertebrae 

(^fCZ 1539) 



Vertebra 



Hei 


gilt of 


Neural 


Spine 


75 


ram 


78 


mm 


80 


mm 


73 


mm 


71 


mm 


65 


mm 


59 


mm 


59 


mm 


52 


mm 


51 


mm 


47 


mm 


41 


mm 


44 


mm 


38 


mm 


36 


mm 


40 


mm 


39 


mm 


40 


mm 


33 


mm 


33 


mm 



Greatest 
Length of 
Vertebra 



1 
2 
3 
4 

5 

6 

7 

8 

9 

10 

II 

12 

13 

14 

15 
16 

17 

18 

19 

20 



35 mm 
35 mm 

35 mm 
38 mm 

36 mm 

35 mm 

35 mm 
31 mm 
31 mm 



29 mm 



26 mm 



Figure 15. All X .5. (A) Eryops sacral vertebra (23) , spine omitted, in 
posterior (1.) , anterior and left views, the latter of MCZ 4305. (B) Eryops 
vertebra 27 (caudal 4) , posterior (1.) and anterior views. (C) Eryops 
vertebra 33 (caudal 10) , posterior (1.) and anterior views. (D) Eryops 
vertebra 43 (caudal 20) , posterior (above) and anterior views. (E) MCZ 
2634, right view, showing matrix (dark stippling) occupying position postu- 
lated for cartilage about centra of postsacral vetebrae. (F) MCZ 1787, 
posterior view, spine missing, showing closure of notochordal canal by 
pleurocentra. (G) AMNH 4183, left view, showing fusion of two successive 
chevrons. (H) MCZ 4325, left lateroanterior view of one to three caudal 
vertebrae showing perforation of dorsal expansion of neural spine on the 
left side for segmental blood vessel. 



32 BREVIORA No. 428 

UC60 and UC117), this being a characteristic of old and of 
very large specimens. The sacral rib may fuse to or coossify 
with its central articulations (FMNH UC117). The coossifica- 
tion of elements is not uncommon at the sacral vertebra, al- 
though the degree of fusion may differ on the two sides (MCZ 
4305,2669,2604). 

THE CAUDAL VERTEBRAE 

( Figs. 5-8 ; 1 5 B-H ; 11 ; the measurements in Table 2 ) 

The total number of caudal vertebrae in Eryops is about 40. 
The number of vertebrae may vary, but the possession of ribs on 
the first eight caudals with chevrons beginning on the eighth 
vertebra is taken as typical. The proximal caudal neural arches 
are closely comparable to the presacral ones in their general fea- 
tures, with less anteroposterior extension at the top, and with the 
zygapophyses placed more closely together. In the trunk region, 
the shaft of the neural spine tends to curve back and then up, 
whereas in the caudal the longer part reaches upward before the 
backward bend, this curvature being more pronounced pos- 
teriorly. The heights of the caudal spines gradually decrease and 
the tops change from an oval outline and become bifurcated, at 
about caudal 4, into two abbreviated horns with rounded sum- 
mits, one on each side, directed first posterolaterally (4-10), 
then laterally (11, 12), and then anterolaterally (13-20). Be- 
hind caudal 20, bifurcation is not noticeable. The horns are not 
always symmetrical; one may be anterior to the other. They 
were covered by skin in life (Romer and Witter, 1941). Near 
vertebrae 20 to 22, the neural spine tips are altered, becoming 
single again. By this point, the spine is much shortened with a 
strong back-and-up curve, is thin from side to side, and is rather 
long anteroposteriorly. 

The zygapophyses are closer together and more sharply tilted 
than in the dorsal vertebrae, and there is a reduction in size. 
In the first dozen caudals, the sides of the neural arch tend to 
be somewhat concave between the zygapophyses, as in the dorsal 
vertebrae. After that they are quite flat. In the MCZ mount 
transverse processes with broad but thin ends that gradually 
narrow occur on the first seven caudals and exceptionally on one 
side of the eighth. Behind the eighth, the pedicels are smooth, 
although convex and swollen along their posterior borders. Each 
vertebra, and hence its pedicels, becomes relatively and increas- 
ingly narrow in the tail, so that the sides of the pedicels are more 



1974 VERTEBRAL COLUMN OF ERYOPS 33 

vertical. The surfaces facing the pleurocentra and intercentrum 
are similar to those in the trunk for most of the length. In old 
specimens, the floor of the neural canal may be complete (Fig. 
11), suggesting that cartilage extended through the area in 
younger specimens. The pedicels narrow below the spinal nerve 
foramina. 

In the proximal part of the caudal column, each pleurocen- 
trum tends to broaden at the top, flatten on the lateral surface, 
and extend relatively far down. They tend to become relatively 
large and more important, and distally may approach the em- 
bolomerous ring type (MCZ 2634). In the sacral region espe- 
cially, the two bony pleurocentra become closely approximated 
dorsally, and the ventral ends tend to approach one another more 
closely than elsewhere. It is possible that in mature specimens 
they fused into a ring, but no such specimens have been seen, 
although intercentrum and pleurocentra together may coossify 
into a ring centrum. Pleurocentrum enlargement and coossifica- 
tion of vertebral elements in the sacral region may be adaptations 
for terrestrial life. 

In the MCZ mount, the first seven intercentra of the tail lack 
a haemal arch; the first chevron is on the right side of vertebra 
8, the left side presenting a transverse process and rib. This 
count may have varied depending on the extent of the coelom 
in the cloacal region. The proximal intercentra are like those of 
the trunk, but capitular facets are well marked and the inter- 
centra are more convex ventrally than dorsal intercentra. A 
medial ventral groove appears in intercentrum 7 for the caudal 
blood vessel which posterior to vertebra 7 courses through the 
foramina of the haemal arches. These arches tend to develop a 
keel on the front and to be flat behind, and to develop small 
terminal cartilages. The shafts gradually become shorter, the 
foramina occupying a progressively greater extent of their length. 
Distally, the ends become flattened and tend to become antero- 
posteriorly oriented, shoe-shaped expansions. 

'To a greater or lesser extent, the neural spines of Eryops ver- 
tebrae show lateral grooves where segmental blood vessels have 
coursed. On each of three caudal vertebrae of MCZ 4325, near 
the front of the bifurcated spine series, a shallow groove appears 
on the left side of the neural spine perforating or indenting the 
dorsal tuberosity of the neural spine (Fig. 15 H). These three 
are unique in the collections I have studied ; presumably all came 
from the same animal. 



34 



BREVIORA 



No. 428 




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VERTEBRAL COLUMN OF ERYOPS 



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VERTEBRAL COLUMN OF ERYOPS 



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38 BREVIORA No. 428 

THE RIBS 

(Figs. 13F-I; 16-19) 

Of the 22 presacral vertebrae, the first (atlas) lacks a rib; in 
some mounts the last presacral rib, that of vertebra 22 has been 
omitted, while in others a misplaced iHum spans too many ribs. 

The head of aU presacral ribs is expanded, with only a con- 
striction separating capitulum and tuberculum. The tubercular 
part is somewhat thicker than the capitular. The articular sur- 
faces are somewhat concave and unfinished, suggesting a carti- 
laginous surface coat. The proximal rib ends are inclined clock- 
wise from the vertical, as are the corresponding articular surfaces 
of the transverse processes (Table 1). The ribs are flat distally. 

There are thickenings of the shaft continuous with capitulum 
and tuberculum, and there may have been considerable variation 
in the form of the uncinate processes. The distal rib ends are 
unfinished, except those of the posterior presacrals, and presum- 
ably ended in cartilage, but this is uncertain. In the MCZ 
mount, uncinate processes are shown on the 2nd through the 
13th ribs, reducing in size and disappearing as the ribs shorten 
posteriorly. Caudal ribs lack these structures. 

DISCUSSION 

It is clear that — distortion apart — individuals of Eryops 
were variable in the following details of their spinal columns: 
extra processes and exostoses; closure of neural canal; degree of 
definition of capitular facets ; relative sizes of neural arches, inter- 
centra and pleurocentra ; degree and asymmetry of coossification ; 
shapes of neural spines and of atlas, axis and the special fourth 
vertebra; angles of inclination of the neural spines, and details 
of configuration of their dorsal expansions. Nevertheless, a clear 
picture emerges of a repeated series of ventral intercentra, dorsal 
neural arches and paired dorsolateral pleurocentra probably 
separated or held together in life by cartilage, which may have 
been continuously woven among the centra or interrupted be- 
tween vertebrae anterior to each intercentrum ; it is not clear 
from the fossil record which was the case. Presumably cartilage 
was more extensive in younger than in older animals. The un- 
finished articular surfaces of vertebral elements clearly reflect 
their continuation in cartilage. 

Arrangement of vertebral elements varies considerably in exist- 
ing Eryops reconstructions. Fossilized pieces, even when found 



1974 VERTEBRAL COLUMN OF ERYOPS 39 

adjacent, are, unless coossified, often difficult to fit exactly to each 
other, presumably due to the missing cartilage. We have found 
no reason to quarrel with Cope's (1890) description, which is 
an excellent guide to vertebral arrangement in Eryops: "The 
neural arch rests exclusively on the pleurocentrum, which in 
turn adheres to the intercentrum behind it by its long side, and 
to that in front by its short side or end", and of caudal vertebrae 
"... the pleurocentra descend further than in the dorsal region, 
rarely to the inferior face of the column, and separating the 
intercentra from mutual contact." These points are illustrated 
in Figures 10 and 15. 

As regards the function of the rhachitomous vertebral column, 
two views have been advanced. Cope (1884) proposed a coat 
sleeve on a semiflexed arm as a model of the flexible cylinder to 
which he earlier (1883) had likened the column of Eryops. He 
saw the osseous elements of the rhachitomous vertebral column 
distributed through a sheath of softer tissue around the noto- 
chord, like segments of the skin of an orange — segments of a 
sphere, as it were. "If you take a flexible cylinder, and cover it 
with a more or less inflexible skin or sheath, and bend that 
cylinder sidewise, you of course will find that the fractures of 
that part of the surface will take place along the line of the 
shortest curve, which is on the side; and, as a matter of fact, 
you have breaks of very much the character of the segments of 
the Permian batrachia" (1883: 276). In a coat sleeve cover- 
ing the semiflexed arm, the folds represented to Cope the 
fractures in the flexible cylinder, the intervals between elements, 
and the spaces between folds the elements themselves. Cope left 
it to future investigations to determine the applicability of his 
model to the history of the vertebral column (1884: 32). 

Parrington (1967) suggested a geodetic spiral, presenting the 
rhachitomous vertebral column as a series of discrete ossicles in 
a cartilage continuum, allowed to twist by virtue of the embed- 
ding of the rather rhomboidal osseous elements interdigitated in 
a cartilage matrix. Such twisting, Parrington suggested, would 
have been essential for amphibious tetrapods like labyrinthodonts 
on coming ashore in order to maintain a center of gravity upon 
a triangle of three legs while bringing the fourth leg forward for 
the next step. Coalescence of neural arches and neural spines in 
certain armored rhachitomes has led Vaughn (1971) to question 
whether or not Parrington's model can have applied to locomo- 
tion in these particular labyrinthodonts. On the other hand, the 



40 BREvioRA No. 428 

flexibility in vertebral column which Parrington's model provides 
would, it seems to me, lend itself ideally to the stereotyped loco- 
motion probably imposed upon a large, tailed amphibian such 
as Eryops by extension of the supracoracoideus muscle, between 
coracoid and humerus, to the forearm through the coraco-radialis 
proprius, as I have discussed it for living urodeles (Moulton, 
1952). While the arrangement may have relieved Eryops from 
decisions leading to more complicated locomotory patterns, the 
simultaneous adduction of the forelimb and flexing of the fore- 
arm, re-establishing at each step the triangle of three legs as 
envisoned by Parrington, would have abetted the twisting of a 
spirally organized vertebral column and vice-versa. It is noted 
that Miner ( 1925) questions the occurrence of the coraco-radialis 
proprius in Eryops. Thomson and Bossy have argued (1970) 
that the temnospondyl and anthrocosaur amphibian lineages 
represented different experiments in a terrestrial vertebral column, 
both based on the principle of a geodetic spiral enunciated by 
Parrington. 

The spiral pattern suggested by Parrington seems reasonable 
as a device for strengthening a vertebral column like that of 
Eryops subject to the stresses of locomotion on land. Are there 
evidences of the proposed torsion in fossil material? I believe so. 
Two intercentra broken and healed during life (MCZ 2621, 
4306 ) , and one that developed a shallow dorsal split also during 
life (MCZ 4305) have been encountered (p. 22). Inasmuch 
as each occurred at an angle clockwise from the primary axis 
(MCZ 2621, 8°; 4306, 30°; 4305, 30°), I suggest that these 
breaks may have occurred in young animals and that they may 
reflect the twisting hypothesized by Parrington in his spiral model. 
Such breaks are not common in fossil collections, the ones de- 
scribed being unique among the intercentra I have studied. 

At present, the detailed pattern of evolution of vertebral centra 
is unsettled. Recent papers of special significance are those of 
Williams (1959), Panchen (1967), Thomson and Vaughn 
(1968) and Thomson and Bossy (1970). Despite gaps in our 
knowledge of the details, there is a general concensus that some 
form of the rhachitomous vertebra was the primitive amphibian 
type; however, increasing evidences of variation in vertebral 
pattern among primitive amphibians greatly complicate the pic- 
ture (R. L. Carroll, personal communication). Eryops itself has 
moved along the temnospondylous line from the most primitive 
labyrinthodont condition (Romer, 1947). In suggesting that the 



1974 VERTEBRAL COLUMN OF ERYOPS 41 

amphibian centrum is homologous throughout, but differently 
subdivided in different hneages, Panchen (1967) introduced an 
idea open to examination by determining the attachments of 
myosepta to the vertebrae, for in all tetrapods, it is clear since 
the important review by Williams (1959), caudal and cranial 
half sclerotomes of successive somites unite, resulting in alterna- 
tion of vertebrae and primary muscle segments. Panchen saw 
the vertebral margin of the myoseptum with its segmental blood 
vessel providing the dividing line between intercentrum and pleu- 
rocentrum. In temnospondyls he saw the myoseptum moving 
posterodorsally, ultimately to the stereospondyl condition, leaving 
an increasingly large intercentrum ahead of the myoseptum until 
the pleurocentrum disappeared. Anteroventral movement of the 
myoseptum on the anthrocosaur line would have resulted ulti- 
mately in the loss of the intercentrum, and in an amniote centrum 
formed from the pleurocentrum posterior to the myoseptum. 

While I have no new evidence on the course of the interseg- 
mental blood vessels in relation to the centra in labyrinthodonts, 
the pathway for the blood vessels and myosepta postulated by 
Panchen (1967: 28) as applicable to fossil material is supported 
by the three neural arches of caudal vertebrae (p. 33) which 
are grooved and perforated on the left side almost certainly for 
the passage of segmental blood vessels. A similar pathway on 
dorsal vertebrae of Eryops could easily have been continued 
along the tops of the transverse processes (p. 20), behind the 
well-defined ridge already described, then dropping behind the 
rib blades almost exactly as Panchen describes and illustrates 
(1967: fig. 5A). Since the courses of segmental blood vessels 
have rarely been preserved in labyrinthodont vertebrae (Pan- 
chen, 1967: 28), these three clearly marked caudal vertebrae 
assume a special significance to our understanding of vertebrae 
and muscle segments in Eryops. 

The broadly flat form and orientation of most of the trunk 
ribs in Eryops probably did not allow for much lateral undula- 
tion, such as suggested by Thomson and Bossy (1970: 11) for 
Ichthyostega. The tail, however, would have served as an excel- 
lent swimming organ ; reconstructions that show it as flexible and 
leaning toward one side on land may be close to the truth. That 
it was strengthened by dorsal tendons seems likely from the 
bifurcate nature of some of the spines. 



42 BREvioRA No. 428 

LITERATURE CITED 

Boll, J. 1880. Geological examinations in Texas. Amer. Natur. 18: 26-39. 
Branson, E. B. 1905. Structure and relationships of American Labyrintho- 

dontidae. J. Geol., 13: 568-610. 
Broili, F. 1899. Ein Beitrag zur Kenntniss von Eryops megacephalus 

(Cope) . Palaeontographica, 46: 61-84, 
Case, E. C. 1911. Revision of the Amphibia and Pisces of the Permian of 

North America. Publ. Carnegie Inst. Wash., No. 146, pp. 1-179. 
. 1915. The Permo-Carboniferous red beds of North America 

and their vertebrate fauna. Publ. Carnegie Inst. Wash., No. 207, pp. 1-176. 
Cope, E. D. 1877. Descriptions of extinct Vertebrata from the Permian and 

Triassic formations of the United States. Proc. Amer. Phil. Soc, 17: 

182-193. 
. 1878a. Descriptions of extinct Batrachia and Reptilia from the 

Permian formation of Texas. Proc. Amer. Phil. Soc, 17: 505-530. 

1878b. The homology of the chevron bones. Amer. Natur., 



12: 319. 

1880a. Second contribution to the history of the Vertebrata 



of the Permian formation of Texas. Paleontological Bulletin No. 32 
(June 5, 1880), pp. 1-22. 

. 1880b. Same title. Proc. Amer. Phil. Soc, 19: 38-58. 

1881. Same title, figures. Paleontological Bulletin No. 32 



(May 2, 1881) , pp. 162-164. 
. 1882. The rhachitomous Stegocephali. Amer. Natur., 16: 



334-335. 

1883. The evidence for evolution in the history of the extinct 



Mammalia. Science, 2: 272-279. 
. 1884. Batrachia of the Permian period of North America. 



Amer. Natur., 18: 26-39. 
. 1890. On the intercentnim of the terrestrial Vertebrata. Trans. 



Amer. Phil. Soc, 16: 243-253. 

-. 1897. Recent papers relating to vertebrate paleontology. Amer. 



Natur., 31: 314-323. 

1898. Syllabus of lectures on the Vertebrata, with an intro- 



duction by H. F. Osborn. Philadelphia: University of Pennsylvania. 
xxxv + 135 pp. 

-, AND W. D. Matthew. 1915. Hitherto unpublished plates of 



Tertiary Mammalia and Permian Vertebrata. Monograph Series No. 2, 
Amer. Mus. Nat. Hist. 

Gregory, W. K. 1951. Evolution emerging, vol. I and II. New York: The 
Macmillan Co. xxvi + 736 pp., 1013 pp. 

Lancston, W., Jr. 1953. Permian amphibians from New Mexico. Uni- 
versity of California Publications in Geological Sciences, 29: 349-416. 

. 1963. Fossil vertebrates and the late Palaeozoic red beds 

of Prince Edward Island. Nat. Mus. Canada, Bull. No. 187. 



1974 VERTEBRAL COLUMN OF ERYOPS 43 

Miner. R. W. 1925. The pectoral limb of Eryops and other primitive 
tetrapods. Bull. Amer. Mus. Nat. Hist., 51: 145-312. 

MouLTON, J. M. 1952. Studies on the derivatives of inverted heteropleurally 
transplanted forelimb buds of Ambystoma maculatum, with particular 
attention to the heterotopic shoulder region. Ph.D. Thesis, Harvard 
University. 379 + xii pp. 

Murphy, J. L. 1971. Eryopsid remains from the Conemaugh Group. Brax- 
ton County, West Virginia. Southeast Geol., 13: 265-273. 

Olson, E. C. 1936a. The ilio-sacral attachment of Eryops. J. Paleontol., 
10: 648-651. 

. 1936b. The dorsal axial musculature of certain primitive 

Permian tetrapods. J. Morphol., 59: 265-311. 

, AND P. P. Vaughn. 1970. The changes of terrestrial verte- 



brates and climates during the Permian of North America, forma et 
functio, 3: 113-138. 

OsBORN, H. F. 1931. Cope: master naturalist. Princeton, N.J.: University 
Press, xvi + 740 pp. 

Panchen, a. L. 1966. The axial skeleton of the labyrinthodont Eogyrinus 
attheyi. J. Zool., 150: 199-222. 

. 1967. The homologies of the labyrinthodont centrum. Evo- 
lution, 21: 24-33. 

Parrington, F. R. 1967. The vertebrae of early tetrapods. In Probleraes 
actuels de paleontologie, ed. by J.-P. Lehman. Paris: Centre Nat. Rech. 
Sci., pp. 269-279. 

Rockwell, H., F. G. Evans and H. C. Pheasant. 1938. The comparative 
morphology of the vertebrate spinal column: its form as related to func- 
tion. J. Morphol., 63: 87-117. 

RoMER, A. S. 1943. Recent mounts of fossil reptiles and amphibians in the 
Museum of Comparative Zoology. Bull. Mus. Comp. Zool., 92: 331-338. 

. 1947. Review of the Labyrinthodontia. Bull. Mus. Comp. 

Zool., 99: 1-368. 

. 1952. Late Pennsylvanian and early Permian vertebrates of 



the Pittsburgh — West Virginia region. Ann. Carn. Mus., 33, Art. 2: 
47-110. 
. 1958. The Texas Permian redbeds and their vertebrate 



fauna. In Studies on fossil vertebrates. Essays presented to D. \L S. 

Watson, ed. by T. S. Westoll. London: The Athalone Press, pp. 157-179. 

. 1966. Vertebrate paleontology, 3rd ed. Chicago: University 



Press, viii + 468 pp. 
, AND R. V. Witter. 1941. The skin of the rhachitomous am- 



phibian Eryops. Amer. J. Sci., 239: 822-824. 

-. 1942. Edops, a primitive rhachitomous 



amphibian from the Texas red beds. J. Geol., 50: 925-960. 
Sawin, H. J. 1941. The cranial anatomy of Eryops megacephalus. Bull. 

Mus. Comp. Zool., 125: 43-107. 
Stickler, L. 1899. Ueber den microscopischen Bau der Faltenzahne von 

Eryops megacephalus Cope. Palaeontographica, 46: 85-94. 



44 BREVIORA No. 428 

Thomson, K. S., and K. H. Bossy. 1970. Adaptive trends and relationships 
in early Amphibia, forma et functio, 3: 7-31. 

, AND P. P. Vaughn. 1968. Vertebral structure in Rhipidistia 

(Osteichthyes, Crossopterygii) with description of a new Permian genus. 
Postilla No. 127: 1-19. 

Vaughn, P. P. 1958. On the geologic range of the labyrinthodont am- 
phibian Eryops. J. Paleontol., 32: 918-922. 

. 1971. A Platyhystrix-like amphibian with fused vertebrae 

from the upper Pennsylvanian of Ohio. J. Paleontol., 45: 464-469. 

Watson, D. M. S. 1919. The structure, evolution and origin of the Am- 
phibia. — The "orders" Rharhitomi and Stereospondyli. Philos. Trans. 
Roy. Soc. Ser. B, 209: 1-73. 

Williams. E. E. 1959. Gadow's arcualia and the development of tetrapod 
vertebrae. Quart. Rev. Biol., 34: 1-32. 

Williston. S. W. 1914. Restorations of some American Permocarboniferous 
amphibians and reptiles. J. Geol., 22: 57-70. 

. 1915. Trimerorhachis, a Permian temnospondyl am- 
phibian. J. Geol., 23: 246-255. 

. 1918. The evolution of vertebrae. Contr. Walker Mus.. 



2: 75-85. 



^^ ^-^ L. APR 2 11977 



lARX^ARO 
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Cambridge, Mass. 27 November 1974 Number 429 

AN O LIS RUPINAE NEW SPECIES 

A SYNTOPIG SIBLING OF 

A. MONTICOLA SHREVE 

Ernest E. Williams^ 

AND 

T. Preston Webster^ 

Abstract. A new species, Anolis rupinae, is distinguished from sibling 
A. monticola by its larger size and different coloration. These two species 
and A. koopmani, which is smaller than either and somewhat different in 
coloration, scale characters, and habitus, constitute a subgroup in the larger 
monticola species group. All three occur on the western end of the Tiburon 
Peninsula of Haiti and have karyotypes derived by fission of one or more 
macrochromosomes from the primitive iguanid complement. The remaining 
four species of the monticola species group are morphologically more diverse 
and occur north of the Cul de Sac depression. Three have the primitive 
karyotype. Anolis rupinae is known only within the habitat of A. monticola, 
but is allotopic to A. koopmani. Chromosome change may have been im- 
portant in the evolution of this distinctive miniradiation. 

As Schwartz ( 1973) has commented, it is clear that the roster 
of Hispaniolan Anolis species is not yet complete. Webster and 
Bums (1973) have just demonstrated that the A. brevirostris 
complex in Haiti must be divided into three species, and Schwartz 
(1973, 1974a) has described two striking new species in the 
Dominican Republic. In addition Schwartz (1974b) has shown 
that the Hispaniolan giant anoles heretofore considered a single 
species, A. ricordi, are better interpreted as three species. 

The key feature of all the recently described Hispaniolan 
anoles is that they are local species. They may or may not be 
abundant where they occur but they all have restricted distribu- 
tions, often montane, sometimes in very arid regions, often less 

^Museum of Comparative Zoology, Cambridge, Massachusetts 02138 



2 BREvioRA No. 429 

obviously circumscribed. Sometimes they are known from a 
single locality, more often from a number of localities relatively 
close together. The species of the ricordi complex have the 
widest ranges of any of the newly recognized forms, but again 
these are allopatric or parapatric, none islandwide. 

We here add still another local species, the major peculiarity 
of which is that it is syntopic with its closest relative. 

Anolis rupinae^ new species 

Holotype. MCZ 121740, an aduh male. 

Type locality. 1.3 km SSW Castillon, Departement du Sud, 
Haiti, T. P. Webster and A. R. Kiester, collectors, 6 September 
1969. 

Paratypes. All Departement du Sud. From the type locality: 
MCZ 121737-39, same data as the type: MCZ 124475-87, 
124612-15, 124851, T. P. Webster collector, 2 July 1970. 

Diagnosis. Close in all scale characters and counts to Anolis 
monticola but differing in larger size and in color. 

Head. Head moderate, head scales rugose or keeled. 9 to 15 
scales across snout between second canthals. Frontal depression 
shallow, scales within it as large or larger than those anterior and 
lateral to it. Anterior and ventral nasal scales (or these plus the 
anteriormost of the lowest loreal row) in contact with rostral. 
7 to 11 scales in contact with rostral posteriorly. Supraorbital 
semicircles separated by two rows of scales. 10 to 17 keeled 
scales in supraocular disk, which is separated from the supra- 
ciliaries by five or more rows of granules. Two elongate supra- 
ciliaries ending at about mid-eye, continued by granules. Can- 
thals distinct; about 6 to 7 canthals, the first three elongate, 
strongly overlapping, first sometimes as long as second. Loreal 
rows 6 to 9, lower row slightly larger, supratemporal rows slightly 
enlarged. Temporals granular, scales behind interparietal very 
slightly enlarged, those anterior and lateral to it markedly larger. 
Interparietal smaller than ear, separated from supraorbital semi- 
circles by 3 to 6 scales. Suboculars separated from supralabials 
by one row of scales. Six supralabials to center of eye. Lower 
eyelid with a window of granular scales. 

Mental much broader than long, in contact with 4 to 8 scales 
between the large sublabials. Only one or two sublabials on each 
side clearly defined, posterior to these there are two to three rows 

^from the Latin rupina: a rocky chasm. 



1974 



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Figure 3. Anolis rupinae, MCZ 124857. Ventral view of chin. 

of enlarged scales alongside the narrow infralabials. Throat 
scales smaller, slighdy elongate anteriorly. 

Trunk. Two to three middorsal scale rows enlarged, keeled. 
Flank granules keeled. Ventrals larger than middorsals, weakly 
keeled, imbricate, subimbricate or rarely juxtaposed. 

Dewlap. Small, in males only but extending to the level of 
the axillae, the largest scales about as large as ventrals, weakly 
keeled. 

Limbs and digits. Dorsal scales of arm and anterior scales of 
thigh and of lower \^g unicarinate. Those of digits and of knee 
multicarinate. 16 to 21 lamellae under phalanges ii and iii of 
fourth toe. 

Tail. Compressed, four middorsal scales per verticil. Postanal 
scales large in male. 

Size. Males to 56 mm in snout-vent length, females to 42 mm. 

Color in life. Webster, 6 September 1969: Adult male type 
from Castillon: "Snout uniform olive green above. Neck subtly 
mottled with shades of olive and pale green. Five pale green 
transverse bands from neck to base of tail. Middorsally the 
nuchal and dorsal crests have alternating areas of pale blue-green 
and olive. More laterally the transverse bands separate olive 
brown blotches with yellowish spots in them. Dorsum of base of 



6 BREVIORA No. 429 

tail with areas of olive alternating with pale green. Distally, tail 
black alternating with greenish cream. 

"Side of snout pale dull green. Eyelids yellow-orange. Iris 
turquoise. Pupil black. Behind eye very dark green. Below it 
pale green. From shoulder along flank a bright green stripe, 
broadening where it crosses the transverse bands, which are 
lighter green on the lower flanks. 

"Below, chin pure bright yellow. Dewlap scales yellow. Skin 
sky blue. Chest scales yellow, those of belly not so bright and 
with the yellow intermingled with areas of dull orange. Under 
tail red orange spots surrounded by yellow scales, the spots be- 
coming more diffuse and vanishing toward the tip. 

"Limbs dorsally with alternating light yellow green and light 
brown. Two green bars on upper and lower arm and tibia but 
three such bars on the femur. Hand and foot similarly cross- 
barred. Ventrally, limbs mottled yellow brown." 

Webster, 1 July 1970 (Castillon) : "All sizes and both sexes 
of rupinae can be distinguished from monticola by the red-orange 
color on the ventral surface. Males are larger, lack the scapular 
patch and have a blue (sky blue) dewlap and a brilliant green 
lateral stripe. The edges of the middorsal band in females are 
straight without scalloping. In both sexes bright yellow around 
the eye." 

Color as preserved. The green stripe so conspicuous in life is 
usually absent in preserved specimens. The red of the ventral 
surfaces also vanishes and the dorsal banding is less vivid. In 
preserved male rupinae the most marked difference from A. mon- 
ticola is the absence of any scapular spot. Females are more 
difficult but the red spots under the base of the tail in life are 
seen in preserved specimens as very white spots which may coa- 
lesce to an undulating bright line under the first part of the tail. 
(In monticola light pigment under the tail is weakly developed 
or present as a straight-edged line. ) 

Karyotype. Diploid chromosome numbers are known for two 
male paratypes (MCZ 124612-13). In diakinesis one has five 
macrochromosomal bivalents and one trivalent, while the other 
has six bivalents and one trivalent. Both have 13 small bodies 
interpreted as microchromosomal bivalents. On the basis of this 
minimal sampling of the one known population, diploid numbers 
in A. rupinae should vary from 38 to 42. 



1974 



ANOLIS RUPINAE NEW SPECIES 




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COMPARISONS 

A. rupinae requires comparison only with certain members of 
the monticola group, and only nominate monticola is known to 
co-occur with it. 

In scale characters rupinae (Table 1) is either identical with 
monticola or (as the snout scales) overlapping. However, though 
both are richly, even gaudily colored, the two species are sharply 
distinct in color (Table 2). The bright flank stripe of rupinae 
is missing in monticola while the two (nuchal) or four (nuchal 
and occipital) black patches with blue ocelli of monticola monti- 
cola and monticola quadrisartus are absent in rupinae. 

In dewlaps, although small in both species, there is a contrast 
also. At the Castillon ravine, monticola has a yellow to reddish 
orange dewlap while that of syntopic rupinae is sky blue. 

Adult size also distinguishes A. rupinae from syntopic A. mon- 
ticola. However, on this point there is a confusion in the litera- 
ture. Thomas and Schwartz (1967) cite the maximum size of 
monticola males as 55 mm (they do not mention the specimen) 
and that of females as 39 mm. They comment on the strong 
sexual dimorphism. We have at hand Thomas Schoener's meas- 
urements for specimens referred to monticola in Schwartz's col- 
lection, the earlier collections of the Museum of Comparative 
Zoology and the American Museum of Natural History. A single 
specimen is reported by Schoener to reach 52.5 mm (AMNH 
49845 from "25 mi N Aux Cayes, Jeremie Road" [corrected by 
Thomas and Schwartz to "32 miles from Aux Cayes on the 
Jeremie Road" from Hassler's field notes] ) . This locality is well 
within the range of monticola monticola and is one of the Hassler 
specimens reported by Williams (1962) as A. monticola and so 
regarded also by Thornas and Schwartz. It is this specimen that 
provided the 55 mm record (Schwartz, personal communica- 
tion). It is now clear that this specimen is not monticola {stt 
below). 

In the relatively large series that the Museum of Comparative 
Zoology now possesses from the Castillon ravine and from other 
localities no male monticola monticola exceeds 45 mm in snout- 
vent length; this size is exceeded by female rupinae (46 mm 
snout-vent length) from Castillon. The Schwartz collection of 
monticola monticola has no male with a snout-vent length greater 
than 42 mm. A. ju. quadrisartus is somewhat larger: Schwartz 
(personal communication) reports males of 48 mm snout-vent 
length. Thus no veritable specimens of monticola or quadrisartus 



1974 ANOLIS RUPINAE NEW SPECIES 9 

are known to reach the 55 to 57 mm snout-vent length of Cas- 
tillon rupinae or of AMNH 49845. 

The latter specimen has been a source of confusion in more 
than size. It was cited by Williams (1962) as the basis of a 
description in life for male monticola. We quote again the de- 
scription which is taken from W. G. Hassler's field notes: 

"General dorsal color Hooker's Green. Saddles brown green, 
three in number, narrowest middorsally, one across shoulder, two 
between fore and hind legs. A light crescent in the temporal 
region. Throat and belly dark olive green. Legs barred. Tail 
barred. Eyes Antwerp Blue, sometimes changing to greenish. 
Edge of orbit yellowish brown. Skin of fan (which is relatively 
small) blue, scales light and dark green. Occurring also in a 
dark phase almost without pattern." 

From the vantage point of present knowledge this description 
cannot be matched with either rupinae as known from Castillon 
or monticola or quadrisartus. Unmentioned are such diagnostic 
elements of color pattern as the flank stripe of rupinae and the 
two or the four ocelli of m. monticola and m. quadrisartus. The 
specimen itself as now preserved shows no pattern at all. 

We may mention here two other difficult specimens (MCZ 
124537-38). Both are males (43 mm and 49 mm in snout-vent 
length) collected by Webster at Catiche within the range of 
quadrisartus. Both are without ocelli and hence are clearly not 
m. quadrisartus or m. monticola. However, they were obtained 
in a lizard market, along with numbers of m. quadrisartus, and 
no detailed notes on color in life exist for them, nothing beyond 
the fact that one had a yellow belly and the other a red one. 

We cannot on present evidence confidently refer either these 
two specimens or AMNH 49845 to rupinae. As preserved, one 
of the Catiche specimens shows the subcaudal white spots char- 
acteristic for rupinae; the other Catiche specimen does not, nor 
does AMNH 49845. Since the one Catiche specimen which had 
a red venter has also the white subcaudal spots in preservation, 
it .may be truly rupinae. In the case of the other two, we call 
attention to the possible existence of still undescribed taxa and 
make no assignment of these specimens. We emphasize that our 
concept of rupinae rests solely upon the animals from the Castil- 
lon ravine. 

It is worth noting that for neither rupinae nor the two sub- 
species of monticola is sexual dimorphism so marked as Schwartz 
assumed it to be for monticola when he included xAMNH 49845 



10 



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No. 429 




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in that species. His ratio of maximum male size to maximum 
female size (55 mm to 39 mm) approximates 1.4. Our revised 
data show monticola monticola with maximum cT size 45 mm, 
maximum ? size 42 mm, equivalent to a ratio of 1.07. The 
comparable data for m. quadrisartus are d 48 mm, $ 42 mm, 
ratio 1.14, and for rupinae d 57 mm, ? 46 mm, ratio 1.24. 

One other species of the monticola group appears very close 
to rupinae. In fact, the resemblances of koopmani to rupinae 
seem as close or closer than those to m. monticola or m. quadri- 
sartus ( Tables 1 and 2 ) . Particularly striking is the red ventral 
coloration found in both rupinae and koopmani, but similar also 
is the presence of a flank stripe, the bluish dewlap, the throat 
spotting and the yellow or orange chin. The major color differ- 
ence between rupinae and koopmani is the absence of trans- 
verse banding in koopmani; only in this aspect of color is rupinae 
closer to m. monticola and m. quadrisartus. 

However, A. koopmani is a grass anole, and the adaptation 
has required a body shape different from that of rupinae or 
monticola (Fig. 5). In size also A. koopmani is distinctive; it 
is the smallest of this group of three related forms ( d maximum 
size 42 mm, 9 maximum size 35 mm, with a ratio therefore 
of 1.2). 

A. koopmani has not before been explicitly referred to the 
monticola group. Rand (1961), however, in describing the spe- 
cies, did suggest that A. monticola, darlingtoni [now etheridgei], 
christophei, hendersoni, baharucoensis, and Xiphocercus [now 
Anolis darlingtoni] might, some or all of them, be closely related 
and that koopmani s> relationship might lie with these. We would 
certainly agree that koopmani has rather close affinities with all 
the species Rand named. However, from rupinae's resemblances 
on the one hand to monticola and on the other to koopmani, it 
is now obvious that these three South Island species are a very 
tight group or subgroup of their own. That they are only a little 
less close to A. rimarum and related but more distantly to A. 
etheridgei, A. christophei and newly described A. fowleri, all 
North Island species (Tables 3 and 4), we will also affirm. We 
now, however, would distinguish between a monticola group 
sensu lato including both North and South Island species and a 
monticola group sensu stricto containing only the South Island 
species. The intimate relationship of the latter clearly separates 
them as a unit, as opposed to the significantly more diverse North 
Island set. 



12 BREVIORA No. 429 

It is clear, therefore, that the description of rupinae (like 
Schwartz's recent discoveries of South Island A. sheplani and 
North Island A. fowleri) does nothing to diminish the intriguing 
differences between North and South Island montane faunas that 
were commented on by Williams and Rand (1969). 

It is too early to do more than draw attention to a problem 
still unsolved. We are in no position to make dogmatic state- 
ments about the montane fauna or faunas. To cite only one 
example, the genus Chamelinorops, which on reasonable grounds 
was thought to be a South Island endemic or even autochthon 
(Thomas, 1966) is now known by a single juvenile from the 
middle of the Cordillera Central (MCZ 126708 from Limoncito, 
southwest of Constanza, La Vega Province, Dominican Repub- 
lic) collected by T. P. Webster. In such cases of rare or local 
species, no safe judgments will be possible until montane His- 
paniola is much better known than it is now. Nevertheless it is 
worth noting that at present no parallel is known in the North 
Island montane fauna to the South Island close-knit triplet of 
monticola, rupinae and koopmani. The North Island set of spe- 
cies are each very distinct from one another morphologically and 
in color and in ecology. The discontinuities are very sharp, so 
sharp that their association as a group is not beyond question. 
This is very different from the South Island series. 

HABITAT, CONGENERS, ECOLOGY 

The type locality. 

Castillon is a market place and a diffuse village at a low point 
in one of several ridges extending north from the Massif de la 
Hotte. The surrounding country is dry and highly disturbed. 
Land not used for subsistence agriculture or pasture is covered 
by brush. Within this area A. rupinae occurs in the small pocket 
of damp and shady habitat in a ravine visible from the hill north 
of Castillon. About 200 meters south of the market stalls the 
road bends sharply, and at this point there is a well-worn trail 
along the side of the ridge. At first it traverses generally open 
slopes, but after a little more than one kilometer the trail enters 
the ravine near the base of a cliff. Between the cliff and the trail 
there is a fairly level area 12 to 15 meters long and 4 to 6 meters 
wide, where all specimens of A. rupinae were collected. 

Only a few medium to large trees grow within the ravine. The 
rocky ravine floor and surrounding slopes are, however, covered 



1974 ANOLIS RUPINAE NEW SPECIES 13 

by a thick growth of brush. Because of the cliff and the steep 
hillsides, the ravine floor is sheltered from the sun. On July 2, 
1970 sunlight did not reach the cliff base until 9:30. Water 
trickles over and seeps from the base of the rock wall. Mosses 
and similar plants flourish on moist and shaded rocks. Below 
the trail the ravine is steep and filled with broken rock. It soon 
widens and becomes more exposed. 

The anoline lizards of the Castillon area. 

In September, 1969 and in June, 1970 the fauna of this area 
was sampled by organizing lizard markets in the Castillon market 
place and by collecting during the day and night around and 
within the ravine. Only A. distichus and A. coelestinus are 
abundant and generally distributed in the region. Both occur on 
the exposed slopes around the ravine but not within it. A third 
widespread and essentially lowland species, A. cy botes, is much 
less common. It does occur in some numbers on rocks along the 
trail entering the ravine and in the ravine itself. Two specimens 
of A. ricordii were procured from a lizard market. 

Four species occurring here are considered montane, since they 
are unknown from coastal localities. (1) A. hendersoni is un- 
common around Castillon, at least along the trail to the ravine. 
A single specimen was collected near the market place, and two 
were taken in trail-edge vegetation near the ravine. (2) On the 
ravine floor and along its approaches A. monticola is abundant. 
While this species occurs throughout the brush in the ravine up 
to the periphery of some bordering garden areas, it is absent from 
drier brush patches on the hillsides. (3) A single Chamelinorops 
barbouri was found along the trail near the ravine. (4) The 
total area inhabited by the population of A. rupinae is probably 
quite small. All specimens were collected from a very short seg- 
ment of the ravine floor. Perhaps it also occurs on the surround- 
ing cliff and slopes of broken rock. It seemed much less common 
in 1969 than in 1970. 

' Of these anoline species, A. rupinae seems to have the strong- 
est requirement for cool, moist conditions. Anolis monticola is 
the only other species common on the ravine floor, but it also 
occurs on the sides of the ravine. Anolis cy botes occurs within 
the ravine close to A. rupinae, but the two species seem to have 
exclusive microdistributions. The other species seem to be intol- 
erant of the ravine environment or were observed too infrequently 
for any statement on co-occurrence with A. rupinae. 



14 BREVIORA No. 429 

A syntopic sibling? 

In one regard A. rupinae appears to be unique among anoles. 
This may be a defect of our present information, but rupinae is 
currently known only within the immediate habitat of A. monti- 
cola. 

It is worth emphasizing that, if confirmed, this is a special 
situation. A. rupinae is close enough structurally to A. monticola 
to be called a sibling of the latter, that is some museum specimens 
and perhaps females in the field have been (see above) or could 
be confused. Many such sibling pairs are known in the West 
Indies, sometimes sibling only in the sense of closest relatives, 
sometimes in the more usual sense of both close relatives and 
barely distinguishable ( under some, usually museum, conditions ) . 
However, such siblings ordinarily are either distinct in climatic 
preference and hence allotopic or they are para- or allopatric 
(as ^. rupinae appears to be to ^. koopmani) . 

Possibly A. rupinae does occur somewhere separately from A. 
monticola. Certainly A. monticola is known from a number of 
localities at which A. rupinae is not known. However, it can be 
pointed out already that the sharply different color patterns of 
these two species (and the dewlap difference at Castillon) and 
the striking difference in size are the kinds of adaptations — the 
color patterns for species recognition, the size difference for 
avoidance of competition for food — that syntopic or widely 
overlapping anoles have evolved in many instances (the Schoener 
rules, Schoener 1970, WiUiams 1972). That rupinae appears to 
be even more rigidly tied to shaded and moist situations than is 
monticola does not damage the suggestion that rupinae and 
monticola are consistently syntopic. On the contrary, this pre- 
sumed greater shade and moisture preference of rupinae makes 
it all the more likely that its preferred habitat is within the habi- 
tat range of monticola. (From the evidence of Castillon rupinae 
does not exclude monticola.) 

The monticola group sensu strict o — an unusual miniradiation 

The status of A. rupinae and A. monticola as unusual siblings 
is compounded by the close relationship of both to A. koopmani. 
While certainly not a sibling — divergence in scale counts, habi- 
tus and size are all reasons for its previously uncertain affinities 
— • the presence of this third species in the same small mountain 
mass is evidence that the monticola group sensu stricto has 



1974 



ANOLIS RUPINAE NEW SPECIES 



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16 BREvioRA No. 429 

evolved differently from most other anole species groups. All 
three are known from moderate elevations (1000' to 3000') 
( Fig. 6 ) , although the lower bound is far more meaningful than 
the upper one. Even with the inclusion of A. koopmani, climatic 
divergence in the monticola group seems relatively limited. 

Unfortunately, distributional and ecological information is so 
scant that interactions among these species are an open problem. 
Only A. monticola has an extensive distribution. A series of 
samples taken along the Les Cayes to Jeremie road indicates that 
the subspecies monticola and quadrisartus are separated by the 
Riviere Glace, a stream originating south of Duchity and flowing 
north, disappearing into limestone hills. While A. rupinae as 
described is known only from Castillon, the unassigned specimens 
from two collections on the Les Cayes to Jeremie road suggest 
the possibility of a broader distribution and contact with both 
subspecies of monticola. 

The scarcity of records for A. rupinae is understandable, since 
its deep shade habitat is limited and very patchy in the highly 
disturbed mid-elevations of the Massif de la Hotte. The apparent 
restriction of A. koopmani to the Les Platons region is more 
enigmatic. It can be common in a shaded coffee patch or in the 
open brush growing in an abandoned citadel. Even on the Les 
Platons plateau it does not always occur in such vegetation and 
it appears to be absent also in comparable areas along the Les 
Cayes to Jeremie road. T. C. Moermond has studied the anoles 
of the Les Platons area and discovered A. monticola, but as yet 
it has not been collected syntopically with A. koopm.ani. (Recall 
that as A. rupinae is larger than A. monticola, A. koopmani is 
smaller (Fig. 5)). Moermond (MS) has documented structural 
habitat and foraging differences for the two. 

The unusual karyology of the monticola group sensu stricto 
has special interest in the context of the morphological, geo- 
graphic and ecological relationships of its members. Departures 
from the ancestral anoline condition that occur in the comple- 
ments of all three can be attributed to centric fission (Webster, 
et al., 1972) , a process that is known in few alpha anoles. Of the 
six ancestral pairs of metacentric macrochromosomes, five or six 
have fissioned in A. monticola to yield diploid numbers of 46 
to 48. Two pairs fissioned to produce the diploid number of 40 
in A. koopmani. As in A. monticola, in A. rupinae there is 
polymorphism for macrochromosomal number with an inferred 
range from six to eight pairs (i.e. none to two pairs fissioned). 



1974 ANOLIS RUPINAE NEW SPECIES 17 

In addition, A. rupinae seems to have one more pair (thirteen) 
of microchromosomes than the ancestral complement (twelve), 
a condition not previously reported. Whether this additional pair 
originated by microchromosomal fission or in the course of change 
in macrochromosomal number and morphology is unknown. 

In addition to supporting the obvious close relationships within 
the monticola group sensu strict o, the shared class of chromosome 
change — fission — may have been critical in the origin and 
di\'ergence of these species. A role for karyotypic differentiation 
in the partial or complete genetic isolation of two populations 
has been suggested by several authors (see Mayr, 1970; White, 
1973; Hall, MS). In addition, chromosomal changes are key 
elements in more complex evolutionary scenarios which envision 
"cascading revolutionary speciation" (Hall, MS) or a genetic 
release that accompanies extensive fissioning and favors adaptive 
radiation (Todd, 1970). The components of these more elabo- 
rate hypotheses — genetic revolutions, genetic effects of fission, 
chance karyotypic change in small populations — are at present 
individually such poorly documented phenomena that the larger 
constructs are particularly open to criticism (see White, 1973 on 
Todd, 1970). We suggest that the derived and complex karyol- 
ogy of this small assemblage of anoles merits further study, both 
as a possible aid to understanding their miniradiation but more 
importantly as a system that may be relevant to larger evolu- 
tionary issues. 

ACKNOWLEDGMENTS 

The discovery and study of Anolis rupinae have been sup- 
ported by NSF grants B 019801X and GB 37731X to E. E. 
Williams. We owe warm thanks to Lamy Camille of Port-au- 
Prince for help with field work and to A. Ross Kiester for com- 
panionship and assistance during the trip which first obtained 
rupinae. 

REFERENCES CITED 

Hall, W. P. III. 1973. Comparative population cytogenetics, speciation 

and evolution of the iguanid lizard genus Sceloporus. Ph.D. Thesis, 

Harvard University. 
Mayr, E. 1970. Populations, Species and Evolution, xv + 453 pp. Harvard 

University Press. 
MoERMOND, T. 1973. Patterns of habitat utilization in Anolis lizards. 

Ph.D. Thesis, Harvard University. 



18 BREVIORA No. 429 

Rand, A. S. 1961. Notes on Hispaniolan herpetology. 4. Anolis koopmani, 

new species, from the southwestern peninsula of Haiti. Breviora, No. 

137: 1-4. 
Rand, A. S. and E. E. Williams. 1969. The anoles of La Palma: aspects 

of their ecological relationships. Breviora, No. 237: 1-19. 
ScHOENER, T. W. 1970. Size patterns in West Indian Anolis lizards. II. 

Correlations with the sizes of particular sympatric species — displacement 

and convergence. Am. Nat. 104: 155-174. 
Schwartz, A. 1973. A new species of montane Anolis (Sauria, Iguanidae) 

from Hispaniola. Ann. Carnegie Mus. 44: 183-195. 
. 1974a. A new species of primitive Anolis (Sauria, Iguanidae) 

from the Sierra d Aboruco, Hispaniola. Breviora, No. 423: 1-19. 

1974b. An analysis of variation in the Hispaniolan giant 



anole, Anolis ricordi Dumeril and Bibron. Bull. Mus. Comp. Zool., 146: 

89-146. 
Thomas, R. 1966. A re-assessment of the fauna of Navassa Island. J. Ohio 

Herp. Soc. 5: 73-89. 
Thomas, R. and A. Schwartz. 1967. The monticola group of the lizard 

genus Anolis in Hispaniola. Breviora, No. 261: 1-27. 
Todd, N. 1970. Karyotypic fissioning and canid phylogeny. J. Theor. Biol. 

26: 445-480. 
Webster, T. P. and J. M. Burns. 1973. Dewlap color variation and elec- 

trophoretically detected sibling species in a Haitian lizard, Anolis hrevi- 

rostris. Evolution 27: 368-377. 
Webster, T. P., W. P. Hall and E. E. Williams. 1972. Fission in the 

evolution of a lizard karyotype. Science, N.Y. 177: 611-613. 
White, M. J. D. 1973. Animal Cytology and Evolution. Third Edition. 

viii + 961 pp. Cambridge University Press. 
Williams, E. E. 1962. Notes on the herpetology of Hispaniola. 7. New 

material of two poorly known anoles: Anolis monticola Shreve and 

Anolis christophei Williams. Breviora, No. 164: 1-11. 
. 1972. The origin of faunas. Evolution of lizard congeners 

in a complex island fauna. In Dobzhansky, Hecht and Steere, eds.. 

Evolutionary Biology 6: 47-89. 



1974 



ANOLIS RUPINAE NEW SPECIES 



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B R E V I O R A 

Vluseiiiii of Comparative "Zoology 



us ISSN 0006-9698 /iDn o 



JST^ 



CAMBRroGE, Mass. 28 March 1975 Number 430 

—n 

A NOUS MARC AN 01 NEW SPEGIESr 

SIBLING TO AN O LIS CYBOTES: 

DESCRIPTION AND FIELD EVIDENCE 

Ernest E. Williams^ 

Abstract. A new species, Anolis marcanoi, very close to A. cy botes, is 
described from the southern slopes of the Cordillera Central in the Domini- 
can Republic. Differing from A. cy botes primarily in the species recognition 
character of a red rather than a white or grey dewlap, it appears to be 
surrounded by populations of A. cy botes and is also sympatric with that 
species in a considerable part of its known range. Ecological differences 
between the two species are not obvious, and it is possible that neither is 
able to displace a resident population of the other. 

In December 1966, Joel D. Weintraub, collecting in the 
Dominican Republic, brought back from San Jose de Ocoa 
two small lizards which in general morphology and in scale 
characters appeared to be assignable to the species Anolis cybotes. 
These specimens, although clearly juvenile, had rudimentary 
reddish dewlaps. The color of the dewlaps immediately at- 
tracted attention, since all the then known populations of A. 
cybotes, a species widely distributed throughout Haiti and the 
Dominican Republic, had yellow or grayish, more rarely orang- 
ish pigmentation in the dewlap but never red except in popula- 
tions at the extreme end of the Southwest Peninsula of Haiti, 
which, while having a reddish dewlap, have also more or less 
keeling on chest and belly scales, while the red-dewlapped form 
from San Jose de Ocoa had perfectly smooth chest and belly 
scales. 

A search for the population from which Weintraub took his 
specimens began in 1968, and over several subsequent summers 
the evidence has built up that the red-dewlapped cybotes-Yikt 

^Museum of Comparative Zoology, Cambridge, Mass. 02138 



2 BREVIORA No. 430 

Anolis is a new species quite distinct from A. cyhotes in electro- 
phoretic characters but nearly indistinguishable in squamation 
and identical in karyology\ The two species overlap spatially in 
a complex way. 

The new species is named for Professor Eugenio de Jesus 
Marcano F., who helped so much in early investigations in the 
Dominican Republic. 

Type. MCZ 131837, an adult male from ca 5 km N La 
Horma, Peravia Pro\'ince, Dominican Republic, collected by 
Jonathan Roughgarden and local inhabitants, 18 July 1972. 

Paratypes. All from Peravia Province, Dominican Repub- 
lic. Same localitv as tvpe: MCZ 131846-75, J. Roughgarden 
and local inhabitants collectors, 18 July 1972; MCZ 143437-43, 
P. E. Hertz and R. B. Huey collectors, 2 August 1974. Lizard 
markets vicinity of La Horma: MCZ 131824-42, local inhabi- 
tants collectors, 19 July 1972; 1 km N Malaqueta on road to 
Valle Nue\'o, W. E. Hall, E. J. Marcano and E. E. Williams 
collectors, 1 Julv 1969; below pines, Sabana Larga, N of San 
Jose de Ocoa: MCZ 117810, W. E. Hall, E. J. Marcano and 
E. E. Williams collectors, 1 Julv 1969; San Jose de Ocoa: MCZ 
104402-03, J. Weintraub coUector, 21 December 1966; 1.3 mi 
S San Jose de Ocoa, 1400 feet: V 34068-79, A. Schwartz and 
local inhabitants collectors, 19 November 1971; bridge over the 
Rio Ocoa S San Jose de Ocoa: MCZ 107072-76, A. S. Rand, 
E. J. Marcano and E. E. WilHams collectors, 27 Julv 1968; 
MCZ 117809, 118606, W^ E. Hall, E. J. Marcano and E. E. 
Williams collectors, 1 Julv 1969; MCZ 143247, P. E. Hertz and 
R. B. Huev collectors, 22 Julv 1974: 3-5 km S San Jose de 
Ocoa: V 21392-95, R. K. Bobilin and R. Thomas collectors, 
24 July 1969; 16 km N Cruce de Ocoa: MCZ 143246, P.E. 
Hertz and R. B. Huev collectors, 21 Julv 1974; 12 km N Cruce 
de Ocoa: MCZ 143245, P. E. Hertz and R. B. Huev collectors, 
22 Julv 1974; 3 km N Cruce de Ocoa, 500 feet: V 35815, A. 
Schwartz and local inhabitants collectors, 27 December 1972; 
coconut grove near Las Carreras on road to San Jose de Ocoa, 
MCZ 115640, W. E. Hall, E. J. Marcano and E. E. W^illiams col- 
lectors, 1 Juh 1969; Las Mayitas, 27 km S San Jose de Ocoa, 

'Like A. cyhotes the new species has the 12 niaciochromosoine, 24 micro- 
chromosome karyotype that occurs so frequently in iguanids and other 
lizards (\V. Hall, personal communication) . 



1975 ANOLIS MARCANOI 3 

550 feet: V 15645, V 15598, J. K. Lewis collector, 3, 5 August 
1968; 6 km N of Bani on road to El Recodo (just S of the first 
ford), P. E. Hertz and R. B. Huev collectors, 20 July 1974; La 
Jina, 7-8 km N of Bani on road to El Recodo: MCZ 143241^3, 
143248-49, 143262, natives for P. E. Hertz and R. B. Huey 
collectors, 20 July 1974; MCZ 143244, P. E. Hertz and R. B. 
Huey collectors, 2 August 1974; 11 km N of Bani on road to 
El Recodo: MCZ 143253-55, P. E. Hertz and R. B. Huey col- 
lectors, 20 Julv 1974; 12 km N of Bani on road to El Recodo: 
MCZ 143256-61, P. E. Hertz and R. B. Huey collectors, 20 July 
1974; 13 km N of Bani on road to El Recodo: MCZ 143250, 
P. E. Hertz and R. B. Huey collectors, 20 July 1974. 

Head. Head moderately massive, snout to posterior border of 
eye about as long as tibia. Head scales mostly smooth. Five to 
nine scales across snout between second canthals. A shallow 
frontal depression. Naris in front of canthal ridge. Anterior 
nasal scale (sometimes divided) in contact with rostral. 

Supraorbital semicircles in contact or separated by one scale 
row, separated from the supraocular disks by single rows of 
granules. Supraocular disks consisting of about six to eighteen 
enlarged weakly keeled scales separated by about five rows of 
scales and granules from the scales of the supraciliary rows. One 
or two elongate supraciliaries continued posteriorly by a double 
row of moderately enlarged scales. Canthus distinct, canthal 
scales four, the second largest. Loreal rows four to seven, the 
lower rows larger. Supratemporal area granular, grading into 
moderately enlarged scales surrounding the interparietal. Inter- 
parietal slightly larger or slightly smaller than ear, separated 
from the supraorbital semicircles by one to three scales. 

Suboculars separated from supralabials by one row of scales 
or in contact, anteriorly grading into loreals, posteriorly grading 
into large scales at the comer of the mouth. Six supralabials to 
the center of the eye. 

Mentals broad as long, usually in contact posteriorly with four 
small throat scales. Infralabials narrow, in contact with two to 
three large sublunate sublabials. Throat scales small, swollen, 
not keeled; only the anterior ones elongate. 

Trunk: Middorsal scales not abruptly larger than flank scales 
(Fig. 1, compare also figures in WilHams, 1963). Ventrals much 
larger than middorsals, cycloid, smooth. Postanal scales en- 
larged, often broken into four. 




Figure 1. Dorsal scales. Left: Anolis marcanoi, Paratype, MCZ 107075. 
Right: A. cybotes, MCZ 115641. Both from the bridge over the Rio Ocoa 
south of San Jose de Ocoa, Peravia Province, Dominican Republic. 



1975 ANOLIS MARCANOI 5 

Gular Jan. Large, scales smooth, no larger than ventrals. 

Limbs and dibits. Hand and foot scales multicarinate. About 
15-22 scales under phalanges 2 and 3 of fourth toe. Largest 
scales of arm unicarinate, of leg smooth or very weakly multi- 
carinate; those of arm smaller, those of thigh larger than ven- 
trals. 

Tail. Compressed, each verticil surmounted by four sharply 
keeled scales, ventrally three pairs of somewhat larger, strongly 
keeled scales. 

Color. Brown with or without obscure dorsal blotching, head 
sometimes distinctly reddish. Dewlap in males distinctly rose- 
red at the edge, more orangish anteriorly and posteriorly, but 
purplish or even bluish toward the center, the colors grading 
into one another. Females with vestigial red-ringed throat fans 
and usually distinct longitudinal dark streaks on the white of 
chin and throat. 

Differential characters. On the classic characters convention- 
ally used in Anolis, especially preserved Anolis, A. marcanoi is 
a poorly differentiated species. No scale characters will con- 
sistently separate marcanoi from cybotes. (From the geographi- 
cally adjacent related montane species, A. shrevei as well as A. 
whitemani of the arid lowlands to the west, A. marcanoi is amply 
distinct by its smooth rather than keeled ventrals.) 

Some specimens of marcanoi have almost no enlargement of 
the middorsal scales anywhere on the dorsum : in most the sacral 
area shows the middorsal scales minimally or not enlarged. How- 
ever, some specimens of cybotes and marcanoi — both sexes and 
all ages — are impossible to distinguish by this character, i.e. in 
these animals of both species the middorsal scales are weakly 
enlarged. No other scale characters seen are even as useful as 
this. 

Color, then, is the major differential character, the male dew- 
lap being especially obvious, but the red in the throat of females 
is also highly diagnostic. 

Distribution. The distribution of A. marcanoi is curiously 
complex ( Fig. 2 ) . It is recorded from the area just south of the 
first ford on the road to El Recodo, north of Bani (here A. 
cybotes is also present) , and from La Jina, the village just beyond 
the first ford (no cybotes obtained). Marcanoi is known as far 



BREVIORA 



No. 430 




A shrevei 



O cybotes 



D marcanoi 



Figure 2. The known distribution of Anolis marconoi. Squares: A. mar- 
canoi. Circles: A. cybotes. Triangle: A. shrevei. 



north on this road as the second ford, and presumably beyond 
it, but this ford is impassable in a rental car. The new species 
occurs also on the slopes of Loma de Pinos, just east of the road 
which connects Constanza in the Cordillera Central via San Jose 
de Ocoa with the road west from Santo Domingo to Barahona. 
There are only sight records from this area. North of Cruce de 
Ocoa on the west road there are occasional records of marcanoi 
south of San Jose de Ocoa ; in these instances it is found on fence 



1975 ANOLIS MARCANOI 7 

posts or in coconut groves, apparently as enclaves with a wider 
but sparse distribution of cyhotes in the surrounding acacia. At 
the bridge just south of San Jose de Ocoa, and inside or in the 
immediate environs of the city, both species occur broadly inter- 
mingled. North of the city as far as La Horma, A. cyhotes is 
known only from lizard markets in villages, while A. marcanoi 
was collected on rocky hillsides, i.e. cyhotes now appears as en- 
claves within populations of marcanoi. At lizard markets up to 

4 km N of La Horma only ynarcanoi was obtained. A single 
specimen of marcanoi is known from 9 km N of La Horma. At 
1 3 km N of La Horma cyhotes reappears and, on the evidence of 
three specimens of this species and no examples of marcanoi, 
appears to separate marcanoi from Anolis shrevei, another cy- 
hotes relative living on the peculiar cold plateau of Valle Nuevo. 

Many more specimens have been seen and even collected than 
have been preserved. Some of the material used for electrophore- 
sis was collected by Thomas Jenssen from nine localities within or 
near the city of San Jose de Ocoa: 8 km N San Jose de Ocoa 
on road to Nizao, 2 km north of the city under the bridge over 
the Rio Ocoa, 8 km N on road to La Horma, at the school in 
the southwest end of town, 3 km W on road to El Pinar, 2 km 

5 at bridge over the Rio Ocoa ( and along the river itself ) , 3 km 
S along a small tributary of the Rio Ocoa. 

In the vicinity of San Jose de Ocoa the two species occur 
almost syntopically but nevertheless with some tendency to ex- 
clusion. It is not easy anywhere to define an ecological difference 
between the two species. The association with rocky, very open 
hillsides is definite for marcanoi in the vicinity of La Horma 
(hence at relatively high elevations), but in the lowlands near 
the intersection with the west road marcanoi is known from a 
shaded coconut grove. Presumably some combinations of tem- 
perature and humidity may provide different optima for the two 
species, but this is a physiological question not yet worked out. 

DISCUSSION 

"Sihling species.'' 

It becomes more and more obvious that, in addition to those 
species in which museum taxonomists rejoice because they are 
very distinct in terms of the characters conventionally studied, 
there are in many groups valid biological species only imperfectly 
separable on museum characters, if at all. This phenomenon is 



8 BREVIORA No. 430 

only interesting in terms of the history of museums, not of biology. 
Museum techniques alter as taxonomy progresses. It will not be 
necessary in the near future to defend or specially comment on 
cases like that here described. Given that species status should 
be recognized by any taxonomist on the full suite of characters 
known for any population and not on the basis of some subset 
selected because of convention or convenience, it is inevitable 
that marcanoi be recognized as a full species. 

The two juvenile specimens on which the discovery of mar- 
canoi was based lack any trace of gular red after eight years in 
alcohol. It would be difficult or impossible to separate them as 
a distinct taxon now, were they all that was available. But this 
is a failure of techniques, a museum failure like the failure of a 
library with books printed with impermanent ink. 

The biological phenomenon in marcanoi and cybotes that is 
interesting is the way in which they overlap. On a large scale 
map, marcanoi and mybotes do overlap over a considerable dis- 
tance. Macro-geographically they are in part sympatric, but 
quite clearly they are rarely syntopic. A. cybotes and A. mar- 
canoi are in this regard rather similar to the Cuban homolechis- 
allogus-sagrei series. As with marcanoi and cybotes, these color 
differences and dewlap differences are more reliable than scale 
differences; the latter are in fact few, minor, and usually bridged 
by intrapopulational variation. In the Cuban series, as with 
marcanoi and cybotes, there may be close physical juxtaposition. 
A walk down a path through the woods on a Cuban finca might 
find two species on adjacent trees, three species not far from one 
another, but close examination would show that one species lived 
in deep shade, one in half shade, one in open sun. Where the 
environment, at the edges of these different habitats, juxtaposed 
the three conditions of shade, half shade and sun, the lizard 
species would also be juxtaposed, while where the environment 
was homogenous over a larger area, there the lizard populations 
would also be homogenous (Ruibal, 1961 ; Ruibal and Williams, 
1961). 

The relations between marcanoi and cybotes, however, ap- 
pears to be subtler than that in the Cuban series. An inadvertent 
experiment may demonstrate this point. The first series of mar- 
canoi were taken in a grove of trees on the right bank of the 
river at the bridge over the Rio Ocoa south of San Jose de Ocoa. 
Only marcanoi was taken in this situation. In several subsequent 
summers the grove of trees has been occupied by cybotes, never 



1975 ANOLIS MARCANOI 9 

by rnarcanoi, which instead has been found on rocks and fence- 
posts on the open road above the grove. Our latest observations 
found the area considerably altered and on the day of observation 
neither species was taken in the grove. Our first ecological judg- 
ment based on collections in the strove during," the first vear were 
that marcanoi preferred shade and cybotes (presumably) sun. 
But subsequent multiple observations both at the grove by the 
ri\er and elsewhere have demonstrated this conclusion to be 
wrong. Apparently cybotes and marcanoi do not respond to the 
environment as litmus paper does to acid or base, or as the 
Cuban species more nearly seem to do. On the contrary, simple 
physical possession seems to be part of the story. By the act of 
collecting we cleared an area of marcanoi. Cybotes was the 
species that moved in and has held this small area ever since. 
There may thus be situations — perhaps many situations — in 
which the advantage to either species is so marginal that it can- 
not dispossess a population in residence. 

By this hypothesis cybotes and marcanoi differ as little physi- 
ologically as they do morphologically. If this be true, it is espe- 
cially interesting that the electrophoretic evidence presented by 
T. P. Webster in Breviora 431 shows that the genetic base for 
these very similar morphological and physiological phenotypes is 
so sharply different. It is once again a lesson that phenotypic 
similarity is an imperfect clue to the continuity of genetic systems. 
Clearly no evidence can be neglected if our object is to establish 
the reality of genetic discontinuity. 

Acknowledgments. Field work has been supported by NSF 
GB-37731X and previous grants to E. E. Williams. Thanks are 
due to all those who so cheerfully participated. 

LITERATURE CITED 

RiiBAL, R. 1961. Thermal relations of five species of tropical lizards. 

Evolution 15: 98-111. 
RuiBAL, R. ANP E. E. Williams. 1961. The taxonomy of the AnoHs homo- 

lechis complex of Cuba. Bull. Mus. Comp. Zool. 125: 209-246. 
Williams, E. E. 1963. Anolis luhiteniani, new species, from Hispaniola 

(Sauria, Iguanidae) . Breviora 197: 1-8. 



B R E V I R A 

MUS. COMP. ZOOL 

Miifeettiw of Comparative Zoology 

APR 3 1975 us ISSN 0006-9098 

CAMWiroGEvM^ss. 28 March 1975 Number 431 

UNlVfcRSiTY 

AN ELECTROPHORETIG COMPARISON 

OF THE HISPANIOLAN LIZARDS 
A NO LIS CY BOTES AND A. MARC AN 01 

T. Preston Webster^ 

Abstract. Samples representing four localities — one for both species, 
two for A. marcanoi, and one for A. cybotes — were examined. Results for 
24 polypeptides are reported, of which 21 were studied in all individuals. 
With each of 10 proteins individual identification is unequivocal or nearly 
so. These data confirm the presence of two species in Peravia Province of 
the Dominican Republic, verify the recognition of the red-dewlapped form 
as the new species A. marcanoi, and indicate that successful hybridization 
and introgression must be rare, if they occur at all. 

Anolis cybotes and the newly described A. marcanoi (Williams, 
1974) are so similar in morphology that no scale character will 
consistently separate them. The latter was recognized only be- 
cause its red dewlap contrasts with the yellow one of the former. 
For anoles such a difference in dewlap color probably is im- 
portant for reproductive isolation (Rand and Williams, 1970; 
Webster and Burns, 1973). In addition, populations of the two 
have been found side by side, but individuals are not known to 
mingle freely. This interaction, which is characteristic of closely 
related anoles, and the difference in dewlap color together pro- 
vide sufficient evidence for the description of A. marcanoi. How- 
ever, the great similarity of the two species invites additional 
information on the extent to which they have diverged and per- 
fected reproductive isolation. I report here a study that used 
starch gel electrophoresis to examine some of their enzymes and 
nonenzymatic proteins. 

^Museum of Comparative Zoology, Harvard University, Cambridge. Mass. 
02138 



2 BREVIORA No. 431 

MATERIALS AND METHODS 

Seven samples were examined. Of 62 individuals collected in 
October 1970 by T. A. Jenssen in the vicinity of San Jose de 
Ocoa, Peravia Province, Dominican Republic, 42 were red- 
dewlapped A. niarcanoi (sample 3a) and 20 were yellow-dew- 
lapped A. cybotes (sample 4a). In July 1974 E. E. Williams, 
R. B. Huey, P. E. Hertz, and R. Holt collected the remaining 
Peravia Province samples: additional short series of both species 
from San Jose de Ocoa (samples 3b and 4b) and A. marcanoi 
from La Gina (sample 1 ) and from the type locality, 5 km N of 
La Horma (sample 2). Sample 5 consists of 4 individuals from 
Debarasse, Departement du Sud, Haiti, a locality a few kilometers 
to the west of Jeremie, the type locality for A. cybotes. The 
Jenssen collection was shipped ali\'e to Cambridge where the 
lizards were bled and frozen, but all other series were frozen in 
the field. 

Methods of sample preparation and horizontal starch gel 
electrophoresis are derived from Selander et al. (1971). Protein 
stains and specific assays are similar to those current in work 
with ^'ertebrates. Procedural details such as buffer systems best 
suited for each protein and minor modifications to published 
assay formulas are available from the author. With the exception 
of hemoglobin and a plasma protein, all proteins were examined 
in tissue homogenates. For some proteins, particularly indophenol 
oxidase, better results were obtained from lizards frozen in Cam- 
bridge than from those frozen in Hispaniola. 

In many reports on genetic differentiation between vertebrate 
populations, including an earlier report on AnoUs species (Web- 
ster, Selander, and Yang, 1972), the results are expressed as 
values of Rogers' coefficient of genetic similarity, S (Rogers, 
1972j. Unfortunately, in some circumstances the effect of this 
formula is counterintuitive. When a single locus is considered 
and no alleles are shared by two populations, the expected sim- 
ilarity is 0. If both populations are polymorphic, however, S is 
nonzero. The results of this study are presented as Nei's normal- 
ized identity of genes, / (Nei, 1972), which is consistently some- 
what (2-7%) larger than S calculated for the same data. 

For the computation of I, each polypeptide is treated as the 
product of a single gene. 



1975 ANOLIS MARCANOI 3 

RESULTS AND DISCUSSION 

Among the polypeptides examined in whole animal homos^e- 
nates, the bands representing 21 could be interpreted with suf- 
ficient consistency to be used in estimating relationships. Of 
these, eight indicate complete or almost complete differentiation 
of all populations of A. marcanoi from those of A. cybotes 
(Table 1). In addition, samples 3a and 4a apparently do not 
share variants of hemoglobin, plasma protein- 1, and indophenol 
oxidase. For four of these proteins (hemoglobin, plasma pro- 
tein-!, protein A, and lactate dehydrogenase- 1 ) the difference 
in electrophoretic mobility is consistent, but so small that an 
indi\idual expressing both variants could be confused with one 
producing a single variant. The differences for 6-phosphoglu- 
conate dehydrogenase, isocitrate dehydrogenase- 1, phosphoglu- 
comutase-1, alcohol dehydrogenase, albumin, and peptidase can 
be scored unequivocally. 

Samples 3b and 4b and the majority of individuals in samples 
3a and 4a were collected 2 km S of San Jose de Ocoa, along the 
bed and banks of the Rio Ocoa. At this locality the two species 
are common and in close contact. In such situations of parapa- 
try or sympatry, discrete variation in the electrophoretic mobility 
of proteins can be more informative than morphological differ- 
entiation. Without genetic analysis or biochemical study of pro- 
tein structure, interpretation of observed differences as allelic 
variation is generally correct (see Johnson, 1973, for criticism 
and enumeration of exceptions). Indeed, the inheritance of 
interspecific differences in some proteins has been observed in 
natural Anolis hybrids (Gorman et al., 1971; Webster, unpub- 
lished) ; and patterns of phenotypic variation in anole popula- 
tions can be explained by simple molecular and Mendelian 
models. Differences in phenotypic frequencies thus indicate the 
presence of reproductive isolation. Detection of isolation does 
not depend on absolute separation and could be inferred even 
from significant differences in allelic frequencies at a few loci. 
For these samples, each of 11 loci indicates an absence of allelic 
exchange. Species status for the populations has no reasonable 
alternati\'e. 

Since codominance is the rule for allelic variation at loci 
encoding proteins (it was observed for all of the protein varia- 
tion within these samples), electrophoretic data can also be used 
to determine whether reproductive isolation is complete and 



4 BREVIORA No. 431 

whether occasional mismating leads to introgression. Thus the 
absence from the San Jose de Ocoa samples of a single individual 
heterozygous for one or more of the six clear allelic differences 
suggests that introgression between the two species must be rare, 
if it occurs at all. The samples are large enough to show that 
Fi hybrid individuals must be uncommon but not so large as to 
exclude their occurrence. Of course, failure to detect hybrid 
individuals does not eliminate the possibility of attempted hy- 
bridization, whatever its frequency, if the issue of such unions is 
inviable. 

A single individual in sample 1 of ^. marcanoi is the exception 
to complete divergence of the two species on the basis of 6- 
phosphogluconate dehydrogenase variants, A heterozygote for 
the common variant of both species, it is not an Fi hybrid (no 
A. cyhotes were collected at this locality). This situation cannot 
be explained, nor does it require explanation. In extensive com- 
parisons of sibling species the characteristic protein variants of 
one are often found in low frequencv in the other (e.g., Prakash, 
1969; Ayala and Powell, 1972; Webster and Burns, 1973). Had 
larger samples and more populations been considered, there prob- 
ably would be fewer loci indicating absolute separation. 

Conspecific populations are quite similar, both throughout the 
small known distribution of A. marcanoi and between A. cybotes 
samples separated by 420 kilometers. The unsatisfactory in- 
dophenol oxidase results — some individuals in sample 1 have 
a variant like that of A. cybotes — provide the only evidence 
for significant differentiation within A. marcanoi. Samples 4a 
and 4b of ^. cybotes are essentially identical and are similar to 
sample 5 for all but one polypeptide (Table 1). If sample 5 is 
accepted as representing A. cybotes from the region of the type 
locality, then, of the two species around San Jose de Ocoa, that 
with the red dewlap has been correctly treated as the new species. 
The difference between intraspecific and interspecific levels of 
similarity is expressed as values of Nei's I in Table 2. 

In nearly all interspecific comparisons involving at least 15 
proteins, one or more has allowed an individual to be identified 
with complete or almost complete confidence. For instance, 
diagnostic proteins giving species assignment with 99% or greater 
certainty were found in each of se\eral extensive comparisons of 
Drosophila sibling species (Ayala and Powell, 1972). In this 
comparison of A. marcanoi and A. cybotes, 10 proteins are diag- 
nostic by the same criterion. Joint consideration of several, par- 



1975 ANOLIS MARCANOI 5 

ticularly the six having very distinct variants, should be sufficient 
to assign any individual to either A. cy botes or A. marcanoi. 
In fact, while the 1970 sample from San Jose de Ocoa was 
divided without error on the basis of dewlap color, for the 1974 
sample it was necessary to use the electrophoretic results to cor- 
rect some of the casual field identifications of juveniles and fe- 
males. Three A. cy botes were misclassed as A. marcanoi and one 
A. marcanoi as A. cybotes. 

Although unnecessary in the analysis of A. marcanoi and A. 
cybotes, the magnitude of a genetic similarity coefficient like 
Nei's / can be used arbitrarily to determine whether two allopat- 
ric populations merit species status. The proteins merely provide 
another class of phenotypic information to be used according to 
established taxonomic procedure, but the genetic interpretation 
is usually retained. A criterion for species recognition can be 
established in the context of several studies of populations at 
diverse taxonomic levels, as judged by morphology or observed 
reproductive compatibility. Similarity values for conspecific pop- 
ulations generally exceed 0.9, and exceptions are often associated 
with insular isolates or other distinctive evolutionary situations 
(see Selander and Johnson, 1973, for a review of such data). 
Infraspecific taxa showing some reproductive isolation differ at 
10 to 25% of their loci, which is 10 to 15 times as much diver- 
gence as between local populations within those taxa (Ayala 
et al., 1974) . I feel that a similarity value of 0.7 or less indicates 
so much genie divergence that it is a fairly conserv^ative criterion 
for species status. On this basis Anolis marcanoi certainly quali- 
fies for recognition as a separate species: in comparisons with 

A. cybotes J /is 0.62. 

ACKNOWLEDGMENTS 

Laboratory work was supported by NSF GB-37731X and 
previous NSF grants to E. E. Williams. I thank those who col- 
lected the samples for this study and P. Haas for writing a com- 
puter program. 



BREVIORA 



No. 431 



Table 1. Polypeptide Variation Within and Between Populations 
of Anolis marcanoi and A. cybotes} 







1 


2 


Sample 
3a 3b 


4a 


4b 


5 


Polypeptide, 
Variants- 


N: 


9 


26 


42 


10 


20 


13 


4 


Albumin 


a 
b 


1.00 


1.00 


1.00 


1.00 


1.00 


1.00 


1.00 


Protein A 


a 
b 


1.00 


1.00 


1.00 


1.00 


1.00 


1.00 


1.00 


Phosphoglucose 
Isomerase 


a 
b 
c 
d 


1.00 


1.00 


.99 
.01 


1.00 


.22 
.75 

.02 


.38 
.62 


.88 
.12 


Lactate 

Dehydrogenase-1 


a 
b 
c 
d 


1.00 


1.00 


1.00 


1.00 


.92 

.08 


.04 
.96 


1.00 


Lactate 

Dehydrogenase-2 


a 
b 


1.00 


1.00 


1.00 


1.00 


1.00 


1.00 


.12 

.88 


Isocitrate 

Dehydrogenase-1 


a 
b 
c 
d 


1.00 


.04 
.77 
.19 


.95 
.05 


.85 
.15 


1.00 


1.00 


1.00 


Malate 

Dehydrogenase-1 


a 
b 


1.00 


1.00 


1.00 


1.00 


1.00 


1.00 


.12 

.88 


Malate 
Dehydrogenase-2 


a 
b 


1.00 


.12 

.98 


1.00 


1.00 


1.00 


1.00 


1.00 


Alcohol 

Dehydrogenase 


a 
b 
c 


1.00 


1.00 


1.00 


1.00 


.12 

.88 


.04 
.96 


.12 
.88 


Glutamic 
Oxaloacetic 
Transaminase-1 


a 
b 


1.00 


1.00 


.99 
.01 


1.00 


1.00 


1.00 


1.00 


6-Phosphogluconate 
Dehydrogenase 


a 
b 
c 
d 

e 


.06 
.94 


.98 
.02 


1.00 


1.00 


1.00 


1.00 


.62 
.38 


Phospho- 

glucomutase-1 


a 
b 
c 


1.00 


1.00 


1.00 


1.00 


1.00 


.92 
.08 


1.00 



1975 



ANOI.IS MARCANOI 



Table 1 — Continued 



Phospho- 
gliiconuitase-2 


a 
b 
c 


.06 
.83 


.83 


.07 

.83 


.85 


.92 
.02 


.81 
.19 


1.00 




d 


.11 


.17 


.10 


.15 










e 










.05 






Peptidase 


a 
b 
c 


.17 
.83 


1.00 


1.00 


1.00 


1.00 


1.00 


1.00 


Fumarase 


a 










.02 


.12 






b 


1.00 


1.00 


.99 


1.00 


.98 


.88 


1.00 




c 






.01 










Indophenol 
Oxidase 


a 
b 






1.00 




1.00 






Hemoglobin 


a 

b 






1.00 




1.00 






Plasma Protein-1 


a 
b 






1.00 




1.00 







Troteins B and C, leucine aminopeptidase, isocitrate dehydrogenase-2, 
a-glycerophosphate dehydrogenase, and glutamic oxaloacetic transaminase-2 
were invariant. 

-Electrophoretic mobility determines order in lists of variants, with 'a' the 
most distant from the origin. 



Table 2. Normalized identity of genes (/) as computed from 21 genes for 
all pairs of samples. 



Sample 
Number 

1 

2 

3a 

3b 

4a 

4b 



.996 



3a 



3b 



4a 



4b 



.998 


.997 


.622 


.611 


.624 


.998 


.999 


.618 


.608 


.623 




.999 


.614 


.604 


.619 






.617 


.606 
.996 


.622 
.958 
.951 



8 BREvioRA No. 431 

LITERATURE CITED 

Ayala, F. J., and J. R. Powell. 1972. Allozymes as diagnostic characters 
of sibling species of Drosophila. Proc. Nat. Acad. Set. USA 69: 1094- 
1096. 

, M. L. Trace Y, L. G. Barr, and J. G. Ehrenfeld. 1974. Ge- 
netic and reproductive differentiation of the subspecies, Drosophila 
equinoxialis caribbensis. Evolution 28: 24-41. 

Gorman, G. C. P. Light, H. C. Dessauer, and J. O. Boos. 1971. Repro- 
ductive failure among the hybridizing Anolis lizards of Trinidad. 
Syst. Zool. 20: 1-18. 

Johnson, G. B. 1973. Enzyme polymorphism and biosystematics: the 
hypothesis of selective neutrality. Ann. Rev. Ecol. Syst. 4: 93-116. 

Nef, M. 1972. Genetic distance between populations. Am. Naturalist 106: 
283-292. 

Prakash, S. 1969. Genie variation in natural populations of Drosophila 
persimilis. Proc. Nat. Acad. Sci. USA 62: 778-84. 

Rand, A. S., and E. E. Williams. 1970. An estimation of redundancy and 
information content of anole dewlaps. Am. Naturalist 104: 99-103. 

Rogers. J. S. 1972. Measures of genetic similarity and genetic distance. 
Studies in Genetics VII (Univ. Texas Publ. 7213): 145-153. 

Selander. R. K., M. H. Smith, S. Y. Yang, W. E. Johnson, and J. B. Gentry. 
1971. Biochemical polymorphism and systematics in the genus Pero- 
myscus. I. Variation in the old-field mouse (Peromyscus polionotus) . 
Studies in Genetics VI (Univ. Texas Publ. 7103) : 49-90. 

, AND W. E. Johnson. 1973. Genetic variation among verte- 
brate species. Ann. Rev. Ecol. Syst. 4: 7.5-91. 

Webster, T. P., R. K. Selander, and S. Y. Yang. 1972. Genetic variability 
and similarity in the Anolis lizards of Bimini. Evolution 26: 523-5.35. 

, and J. M. Burns. 1973. Dewlap color variation and electro- 

phoretically detected sibling species in a Haitian lizard, Anolis bre- 
virostris. Evolution 27: 368-377. 

Williams, E. E. 1974. A new Anolis, sibling to A. cy botes. Anolis marcanoi 
new species: description and field evidence. Breviora 430. 



B R E V I R A 

Miiseiiiii of Comparative Zoology 

us ISSN 0006-9698 ^^^S. COMp. ZOOL 
LtBRARY 

Cambridge, Mass. 28 March 1975 , -^Number 432 

^^^ APRo 1975 

EVOLUTION AND GLASSIFIGATI01\ro 
OF PLAGODERM FISHESNjVErsjty 

Robert H. Denison 

Abstract. The assumption is made that within the Subclass Placodermi 
a shoulder girdle that is short anteroposteriorly is primitive. Most orders 
retaining this feature show distinctive specializations: thus the Rhenanida 
are ray-like, the Ptyctodontida are chimaeroid-like, the Pseudopetalichthyida 
have large, dorsal eyes, and many Acanthothoraci have dorsal nostrils. The 
Slensioellida show few specializations are are believed to be the most primi- 
tive known Placodermi, yet they possess the three characters that distinguish 
the subclass: 1) gills anteriorly placed under the neurocranium; 2) a neck 
joint between the neurocranium and synarcual; and 3) dermal bones. The 
primitively short shoulder girdle becomes lengthened to form a thoracic 
shield in several stages. Some Acanthothoraci add posterior lateral and 
posterior dorsolateral plates. The Petalichthyida add a long ventral shield. 
Primitive Arthrodira lengthen the lateral shield and close it behind the 
pectoral fins which then attach through fenestrae. Finally, the Antiarcha 
develop a long, boxlike shield and transform the spinal plates into peculiar 
pectoral appendages. A phyletic classification of Placodermi is attempted. 

INTRODUCTION 

The Placodermi are a suborder of fishes whose known history 
is practically restricted to the Devonian period unless, as some 
think, they were ancestral to the chimaeroids. During that rela- 
tively short time span they underwent a considerable radiation 
and gave rise to 34 families and about 170 genera. In recent 
years they have been the subject of considerable research by 
many paleontologists. Yet, in spite of a great advance in our 
knowledge of the group, there is still little agreement about their 
evolutionary history and classification. This results from widely 
different assumptions about what constitutes primitive or derived 
characters within the group. Gross (1954) argued that an elon- 



2 BREVIORA No. 432 

gated thoracic shield such as occurs in early Arthrodira is primi- 
tive, and the well-documented reduction of this shield within 
Arthrodira may be adduced to support this. Westoll (1945) 
likewise placed the long-shielded "Arctolepida" at the base of 
his placoderm phylogeny, and Miles ( 1 969 ) has concluded that 
the formation of a firm thoracic shield, together with the develop- 
ment of a neck joint, was the fundamental placoderm adapta- 
tion. On the other hand, Stensio in various works (e.g., 1969- 
1971) has based his classification primarily on the pectoral fin 
and endoskeletal shoulder girdle; following the fin-fold theory 
of paired fin origins, he believes that the primitive state is 
long-based pectoral fins together with an elongated endoskeletal 
shoulder girdle for their articulation. 

CHARACTERS OF PRIMITIVE PLACODERMI 

In my opinion, neither of these theories is correct, and my 
classification and phylogeny is based on the assumption that 
within the Placodermi an anteroposteriorly short shoulder girdle 
is primitive. The justification for this assumption is the fact that 
a short exoskeletal shoulder girdle occurs in all other groups of 
fishes with bony exoskeletons, and a short scapulocoracoid is 
characteristic of Chondrichthyes. It is only in certain groups of 
Placodermi, the Petalichthyida, Arthrodira, Phyllolepida and 
Antiarcha, that the exoskeletal shoulder girdle is elongated to 
form a thoracic shield, and this can be taken as an indication 
that it is a derived state within Pisces and within Placodermi as 
well. On the assumption, then, that a short shoulder girdle is 
primitive within Placodermi, we may look at the groups that 
possess this character for other primitive states. The classification 
used in this discussion is given in the appendix, and is indicated 
pictorially in the phylogenetic chart (Fig. 6); some parts of it 
will be discussed later. 

The following orders have a short exoskeletal shoulder girdle: 
Stensioellida ( Stensioella ) 

Rhenanida {Gemuendina, Asterosteus, Ohioaspis, Jagorina) 
Pseudopetalichthyida {Pseudopetalichthys, Paraplesiohatis) 

Acanthothoraci {Palaeacanthaspis, Kosoraspis, Radotina, 
Kolymaspis, Kimaspis) 

Ptyctodontida (8 genera) 



1975 PLACODERM FISHES 3 

AM of these orders appear in the Lower Devonian; they show 
the following characters which may be primitive : 

Thoracic region. 

1) The ventral shoulder girdle (Figs. 1-2, sh) consists of a 
single pair of plates homologous either to the interolaterals or 
anterior ventrolaterals of Arthrodira; between them a median 
plate has been identified only in Ptyctodontida. 

2) The lateral shoulder girdle consists only of anterior laterals 
and anterior dorsolaterals, except in some Acanthothoraci (Fig. 
IC) where posterior laterals and posterior dorsolaterals are also 
present. 

3) The spinal plates are absent, or small and doubtfully dis- 
tinct, except in Acanthothoraci and some Ptvctodontida (Fig. 
IC-D, Sp). 

4) A median dorsal plate is probably absent in Stensioellida 
and Pseudopetalichthyida. 

5) Pectoral fins are narrow-based, even in Rhenanida where 
the fins are much expanded distally ( Fig. IB). 

6) There is no exoskeletal craniothoracic joint, except in 
Ptyctodontida where it is developed differently than in Arthro- 
dira and Antiarcha. 

7 ) The anterior vertebrae are fused to form a synarcual ( Figs. 
1-2, syn) which articulates with the occipital region of the neu- 
rocranium (not known in Acanthothoraci). 

Skull. 

8 ) The neurocranium is long and slender with a long occipital 
region, except in Ptyctodontida where it must have been short. 

9 ) The dermal cranial roof bone pattern may be variable and 
unstable with relationships between bones and sensory canals not 
firmly established, except in Ptyctodontida. 

10) Dermal cranial roof bones may be small and part of the 
rpof may be covered with thin, superficial tesserae in Acantho- 
thoraci (Fig. 3, te) and Rhenanida; much of the skull in Sten- 
sioellida (Fig. 2A) is covered with denticles or tesserae; the 
central part of the cranial roof of Pseudopetalichthyida is cov- 
ered with small dermal bones, but there may have been denticles 
or tesserae elsewhere. Denticles or tesserae are unknown in 
Ptvctodontida, but mav have covered the snout and cheeks where 
dermal bones are largely absent (Fig. ID). 




Figure 1. Placoderrai with short shoulder girdles: A, Order Pseudope- 
talichthyida (ventral view of Pseudopetalichthys problematica, X0.66, from 
Gross, 1962) ; B, Order Rhenanida (ventral view of Gemuendina stuertzi, 

X0.60, from Gross, 1963) ; C, Order Acanthoihoraci (lateral view of shoulder 
girdle of Palaeacanthaspis vasta, X0.94, from Stensio, 1944); D, Order 
Ptyctodontida (lateral view of head and shoulder girdle of Rhamphodopsis 
thrdplandi, X2.5. fiom Miles, 1967). Adl, anterior dorsolateral plate; Al, 
anterior lateral plate; ba, basal elements of pectoral fin; br, branchial arches; 
en, endocranium; Ig, lower jaw; It, lower dental plate; Md, median dorsal 
plate; mk, Meckel's cartilage; or, orbit; pcf, pectoral fin; Pdl, posterior 
dorsolateral plate; PI, posterior lateral plate; pvf, pelvic fin; sh, shoulder 

girdle; Sp, spinal plate; syn, synarcual; ut, upper dental plate. 



1975 PLACODERM FISHES 5 

Jaws and Gills. 

1 1 ) The jaws, where known, are more or less transverse and 
lack large dermal elements (Fig. lA-B, 2B), except in Ptycto- 
dontida where they are directed more anteroposteriorly and carry 
large crushing or sectorial tooth plates (Fig. ID, ut, It). 

12) Gill covers (submarginals) may be present, though they 
are not known in Acanthothoraci and their dermal bones are 
small in Ptyctodontida. 

Sensory organs. 

1 3 ) The orbits are small and lateral in Stensioellida and most 
Acanthothoraci, large and dorsolateral in Ptyctodontida, and 
dorsal in Pseudopetalichthyida, Rhenanida and one late genus 
of Acanthothoraci; the last condition is surely specialized. 

14) The nostrils are known only in Rhenanida and Acantho- 
thoraci (Fig. 3, no) where they are usually dorsal, a condition 
that is surely specialized. In Stensioellida, Pseudopetalichthyida 
and primitive Acanthothoraci they are presumed to be anterior 
or anteroventral ; there are no clues to their position in Ptycto- 
dontida. 

Body and fins. 

15) The body is depressed and tapers to a diphycercal tail 
(not known in Acanthothoraci) . 

16) Dorsal fins are little developed except in Ptyctodontida; 
there are dorsal ridge scales in Pseudopetalichthyida (Fig. lA) 
and Stensioellida and the latter has a small dorsal fin (Fig. 2 A, 
df ) at the base of the tail; an enlarged ridge scale forms a small 
dorsal spine in Rhenanida. (This region is not known in Acan- 
thothoraci.) 

17) Pelvic fins (Figs. 1-2, pvf) are long-based and semicircu- 
lar in Rhenanida, Stensioellida and Pseudopetalichthyida; they 
are specialized by the development of claspers in male Ptycto- 
dontida. 

Histology. 

18) The histology of the Lower Devonian members of the 
groups under discussion is practically unknown. There is a pos- 
sibihty that the Stensioellida had denticles composed of dentine, 
and if so, this would be the only occurrence of this tissue in 
Placodermi except for the tooth plates of Ptyctodontida. Typi- 
cally in other Placodermi the superficial layer is reduced and the 
external part of dermal bones is composed of semidentine or bone. 



6 BREVIORA No. 432 

PRIMITIVENESS OF PLACODERM ORDERS 
WITH SHORT SHOULDER GIRDLES 

In reviewing the list of probable primitive characters, it is 
clear that the Ptyctodontida (Fig. ID) do not share many of 
them. This may be due to the fact that only the shoulder girdle 
is known in Lower Devonian ptyctodonts while other characters 
are determined from Middle or Upper Devonian genera which 
are specialized or advanced in the following ways: the presence 
in the shoulder girdle of an anterior medioxentral, a median 
dorsal, spinal plates in some, and an exoskeletal craniothoracic 
joint; in the shortness of the exo- and endocranium, well-estab- 
lished cranial roof pattern without tesserae (except perhaps 
anteriorly and on the cheeks), large dorsolateral eyes, large 
dermal jaw elements, firm attachment of palatoquadrate to en- 
docranium, dorsal fins, and pelvic fins with claspers in males. 

It is clear that the ray-hke Rhenanida (Fig. IB) are also spe- 
cialized, even in the earliest known Lower Devonian forms. They 
have a much flattened body, greatly expanded pectoral fins, 
dorsal eyes and nostrils, a median dorsal plate, and a dorsal spine 
on the bodv. 

The Acanthothoraci, with the exception of the Radotinidae, 
are advanced in having the lateral parts of the shoulder girdle 
lengthened by the addition of posterior lateral and posterior 
dorsolateral plates (Fig. IC) ; well-developed, projecting spinal 
plates as well as median dorsal plates are present. The skull in 
all members of the order is distinguished by its narrow propor- 
tions, subparallel sides, and deeply embayed posterior margin 
with strongly projecting paranuchals. Primitively, (Palaeacan- 
thaspidae) the eyes were lateral and the nostrils probably ventral, 
but the nostrils, or both the nostrils and eves have moved to the 
dorsal side in Radotinidae (Fig. 3) and Kolymaspidae, both of 
which have a prominent rostrum. 

The poorly known Pseudopetalichthyida (Fig. lA) are surely 
speciahzed in their relatively large, dorsal eyes, the long preorbital 
region, and possibly in the absence of tesserae, at least on the 
cranial roof. Their jaws (Fig. lA, Ig), though not well under- 
stood, appear to be peculiarly specialized. 

This leaves only the Stensioellida, which exhibit very few 
characters that can be interpreted as advanced, and are con- 
sidered to be the most primitive Placodermi known, even though 



1975 



PLACODERM FISHES 



they are not the earliest members of the subclass. Based on the 
two specimens of Stensioella (Fig. 2) from the Hunsriickschiefer 
of Germany, the body appears to be somewhat depressed, broad- 
est in the head and shoulder regions, and tapering backwards 
towards the tail. Flattening after burial spread apart the two 
halves of the shoulder girdle (Fig. 2, sh), making it difficult to 




— pcf 




Figure 2. Stensioella heintzi (the only known reprepresentative of the 
Order Stensioellida) , X0.44, from Gross, 1962: A, dorsal; B, ventral, art, 
jaw articulation; br, branchial arches; Ce, central plate; df, dorsal fin; dn, 
denticles; en, occipital region of endocranium; hy, hyomandibular; mo, 
mouth; pcf, pectoral fin; pvf, pelvic fin; sh, shoulder girdle; syn, synarcuaL 



8 BREVIORA No. 432 

interpret, but the bones are tuberculate and thus largely exo- 
skeletal, even though individual dermal bones cannot be identi- 
fied. Clearly the shoulder girdle is short anteroposteriorly, lacks 
a median dorsal and median ventral, and has no large or pro- 
jecting spinal plates. Each half of the shoulder girdle has an 
inner or medial lamina which forms a postbranchial wall; such 
a wall occurs in many placoderms, but is absent in primitive 
Arthrodira, so this mav well be an advanced character in Sten- 
sioella. The pectoral fins (Fig. 2, pcf) are narrow-based, scale- 
covered and with ceratotrichia distally, but their inner skeleton 
is unknown. There is no exoskeletal craniothoracic joint, but 
apparently there is a synarcual formed of fused anterior verte- 
brae (Fig. 2, syn) that articulates with the occipital region of 
the endocranium. The body is covered with denticles (Fig. 2, 
dn) which possibly ha\'e pulp ca\ities and thus perhaps were 
composed of dentine, and possibly, though not certainly, were 
attached to thin tesserae. There are long-based, semicircular 
pelvic fins (Fig. 2, pvf), and a small, delicate dorsal fin (Fig. 2, 
df ) at the base of the tail, the termination of which is unknown. 

Judging from its manner of preservation, the head and body 
were depressed dorsoventrally, but only moderately broad. The 
neurocranium must have been long and relatively slender, but 
was poorly ossified, except in the occipital region where an articu- 
lation was developed for the synarcual (Fig. 2, en). The dermal 
covering of the head was largely denticles, possibly attached to 
tesserae, but there are at least three small bones with radiating 
structure — a median postpineal and paired centrals ( Fig. 2A, 
Ce). The orbits have not been seen, but must have been lateral, 
and the nostrils do not appear on the dorsal surface of the head 
so are assumed to be anterior or anteroventral. The supraorbital 
sensory canals are bounded by large tubercles and are presumably 
quite superficial; from the snout they run subparallel back to the 
middle of the skull. Posterior pit lines are shallow grooves on the 
central plates. The mouth (Fig. 2B, mo) is ventral, but only a 
short distance behind the rostrum. The palatoquadrates and 
Meckel's cartilages carry no dermal jaw bones, only small denti- 
cles. As interpreted by Gross (1962), the jaw suspension was 
hyostylic, but this is not certain. There appear to be five bran- 
chial arches (Fig. 2B, br) and these extend far anterior under 
the endocranium. 

The single species that constitutes the Order Stensioellida has 
many characters that are considered primitive within the placo- 



1975 PLACODERM FISHES 9 

derms, but shows no easily identifiable specializations or unique 
derived characters that can be used to distinguish it from other 
placoderni orders. Nonetheless, it seems to be a distinct order 
occupying an isolated position as an offshoot from the base of 
the placoderm stem. 

DIAGNOSTIC CHARACTERS OF PLACODERMS 

That Stensioellida are placoderms is indicated by their posses- 
sion of three characters : 1 ) the gills lie far forward under the 
neurocranium ; 2 ) there is a neck joint between the endocranium 
and synarcual; and 3) there are dermal bones on the head and 
shoulder girdle. The first two characters are shared by the Holo- 
cephali which may support, though it does not establish, their 
postulated relationship to Placodermi. But the possession of all 
three features is unique to Placodermi, and for that reason their 
significance requires further consideration. 

Miles (1967, 1969) attempted to show that the neck joint 
arose to compensate for the rigidity of the anterior part of the 
body when it became enclosed within a thoracic shield. How- 
ever, this joint occurs in the placoderm orders discussed above 
which have a short shoulder girdle and no rigid thoracic armor. 
The same is true in chimaeroids so one may question whether it 
was the evolution of a stiff armor that led to the development 
of the neck joint. The joint permits largely vertical movement 
between the head and shoulder girdle and functions in three main 
ways (Miles, 1967) : 1 ) to aid in locomotion by control of pitch- 
ing equiHbrium ; 2 ) to aid in feeding by permitting a wider gape 
and by helping to force food into the esophagus; and 3) to aid 
in respiration by forcing water through the gills. The first was 
probably of only minor importance to early placoderms which 
were slow-swimming, benthonic forms. The second may have 
been important to some later, predaceous placoderms, but the 
early ones had small mouths and surely ate small food that did 
not require a wide gape. However, the neck joint may have been 
necessary for respiration when the gills became crowded under 
the neurocranium; then, a raising and lowering of the head 
would help to force a stream of water through the gills. Thus 
ithe neck joint may have been related to the anterior position of 
the gills under the head; instead of being a response to the 
rigidity of the thoracic region, it may have permitted the later 
development in some groups of a stiff trunk armor. 



10 



BREVIORA 



No. 432 



Dermal bones are characteristic of Placodernii, and typically a 
superficial layer of dentine is absent and their surface is formed of 
semidentine or bone. In the Lower Devonian groups with a short 
shoulder girdle, specimens are either unavailable or unsuitable 
for histologic study so superficial tissues have not been identified. 
Primitive or ancestral Placodermi might be expected to retain 
dentine in teeth, denticles or tubercles, and Gross (1962) has 
recognized what may be pulp cavities in the denticles of Sten- 
sioella, suggesting that they were made of dentine. Lower 
Devonian Rhenanida have not been studied histologically, but 
the Middle Devonian members have semidentine superficially. 
Ptyctodontida have dentine in their tooth plates (0rvig, 1957), 
the only occurrence of this tissue in later Placodermi. 

The problem of dermal bone origins in placoderms is com- 
plicated by the presence of tesserae in certain groups — the 
Rhenanida, Acanthothoraci, Lower Devonian Petalichthyida, 
and possibly Stensioellida. Since tesserae occur mostly in early 




Figure 3. Radotina kosorensis, dorsal view of incomplete cranial roof, 
X0.9, from Gross, 1958. Ce, central plate; 11, main lateral line; no, nasal 
opening; or, orbit; pp, posterior pit line; Pro, preorbital plates; Pto, post- 
orbital plate; Ro, anterior plate perhaps homologous to rostral or pre- 
median; soc, supraorbital sensory canal; te, tesserae. 



1975 PLACODERM FISHES 11 

forms, they are probably a primitive character, as has been 
maintained by Gross (1959). He has shown in Radotina (Fig. 
3, te) that tesserae are thin, superficial structures that occur for 
the most part between bones, and that do not fuse together to 
form bones or even their superficial parts. In Rhenanida they 
are homologous to the scales that cover the body (Gross, 1963). 
They may be considered remnants of the dermal scales that were 
the only exoskeleton of ancestral placoderms, and as such are 
comparable in general to chondrichthyan scales. When bones 
first appeared in placoderms, they apparently arose deeper in 
the dermis quite independently of the tesserae and also of the 
lateral line system. The depth of their formation may account 
for the absence of any true dentine on the bones of typical Pla- 
codermi, and also for the fact that the course of the lateral line 
canals in Rhenanida and Acanthothoraci is not dependent on 
the dermal bones. Presumably the close relationship between 
the dermal bones and lateral line canals was secondary and, as 
suggested by Parrington ( 1 949 ) , the precursors of dermal bones 
may later have come to influence the direction of growth of 
lateral line primordia. 

The pattern of dermal bones on the skull differs in the various 
groups of Placodermi yet shows enough similarities to suggest 
that, in most cases at least, it was derived from a common an- 
cestral pattern. In Stensioellida the pattern is hardly developed 
for in the cranial roof there is onlv a median bone identified as 
a postpineal and paired bones that resemble centrals (Fig. 2 A, 
Ce). Likewise in the Lower Devonian Rhenanida the cranial 
roof largely lacks dermal bones, though laterally there are sub- 
orbitals, submarginals and possibly paranuchals. In all other 
groups, except perhaps the poorly known Pseudopetalichthyida, 
the skull bones are developed according to a similar pattern. 
This pattern includes some or all of the following : 1 ) median 
nuchal, postpineal, pineal and rostral; 2) paired centrals over 
the otic region; 3) paired paranuchals and marginals carrying 
the main lateral line forward; 4) paired pre- and postorbitals 
o^^er the orbits; 5) paired postnasals beside the nostrils; and 
6) paired suborbitals, postsuborbitals, postmarginals and sub- 
marginals in the cheek and opercular region. Much of this pat- 
tern is becoming established in the Acanthothoraci (Fig. 3), 
while in Ptyctodontida, Arthrodira, Phyllolepida and Antiarcha 
there are relatively stable cranial bone patterns, though with 
characteristic modifications in the various subgroups (Figs. 4-5). 



12 BREVIORA No. 432 

PHYLETIC HISTORY OF PLACODERMI 

In my theor\' of placoderm evolution, as presented pictorially 
in the phylogenetic chart (Fig. 6), particular emphasis is given 
to the dermal shoulder girdle. This remains short in Stensioellida, 
Pseudopetalichthyida, Rhenanida and Ptyctodontida, while the 
first steps towards lengthening it to form a thoracic shield are 
seen in some Acanthothoraci (Palaeacanthaspidae and Koly- 
maspidae), where posterior laterals and posterior dorsolaterals 
are added (Fig. IC, PI, Pdl). The second stage is the develop- 
ment of a ventral shield composed, in addition to interolaterals, 
of anterior and posterior ventralaterals and anterior and posterior 
medioventrals ; this is seen in Petalichthyida and Arthrodira. 
Early members of the latter group go one step further in uniting 
the posterior parts of the ventral and lateral shields behind the 
pectoral fins to enclose pectoral fenestrae (Fig. 5B-F, pf). The 
Antiarcha have the longest thoracic shield and have a posterior 
median dorsal incorporated in it (Fig. 5K, Pmd). 

There are three major phylogenetic problems that require 
special mention, the first involving the Petalichthyida (Fig. 5A). 
Their thoracic shield might have evolved quite independently 
from that of Arthrodira, in which case a relationship to Pseudo- 
petaUchthyida should be considered. However, since the latter 
group is so poorly known and the petalichthyid thoracic shield is 
so similar to that of Arthrodira, this theorv has little to recom- 
mend it. Secondly, the petalichthyid thoracic shield may have 
arisen as a result of a posterior reduction of the lateral parts of 
the arthrodire shield. There is no evidence to support this, and 
in fact it is quite unlikely that the petalichthyid cranial roof was 
derived from the arthrodire type, so this theory is rejected. The 
third theory is that the petalichthyid thoracic shield represents 
an intermediate evolutionary stage, more advanced than in Acan- 
thothoraci in the possession of a ventral shield, but less advanced 
than early Arthrodira as the pectoral fins are completely behind 
the shield. This theory seems most probable and is supported by 
the retention of certain primitive characters in Petalichthyida, 
such as the two pairs of paranuchals and tesserae on the cheeks. 

The evolutionary position of Phyllolepis (Fig. 4) is also con- 
troversial because, though it has a moderately long thoracic 
shield, it lacks posterior laterals and posterior dorsolaterals. Is 
the absence of these plates the result of a phyletic reduction, or 
did Phyllolepis branch off the arthrodiran ancestral line before 



1975 



PLACODERM FISHES 



13 



?Ptn 




Figure 4. Phyllolepis o-rvini, dorsal view of cranial and thoracic shields, 
X0.2, modified from Stensio, 1936. Adl, anterior dorsolateral plate; Al, 
anterior lateral plate; cc, central sensory canal; ioc, infraorbital sensory 
canal; Ic, main lateral line; Md, median dorsal plate; Mg, marginal plate; 
Nu, nuchal plate; Pnu, paranuchal plate; pp, posterior pit line; Pro, pre- 
orbital plate; ? Ptn, possible postnasal plate; Pto, postorbital plate. 



these plates were acquired? Since this genus is known only from 
the late Famennian there is little evidence to decide this question. 
However, the genus Antarctaspis, known only from an imperfect 
cranial roof, seems in some ways to bridge the gap between Phyl- 
lolepis and primitive Actinolepina, which suggests that Phyllole- 
pifia were derived from the latter by a reduction of the thoracic 
shield, and, of course, by considerable modification of the cranial 
roof. 

The Ptyctodontida (Fig. ID) are a third phyletic problem. 
If it is accepted that their short dermal shoulder girdle is a prim- 
itive character and not the result of reduction, they cannot be 
derived from Arthrodira, Petalichthvida or some Acanthothoraci. 



14 BREVIORA No. 432 

Yet in their dermal cranial bones thev show many resemblances 
to these groups, so they probably had an ancestor with a short 
shoulder girdle and the basic placoderm cranial bone pattern. 
The Radotinidae are the only known group that satisfies these 
conditions, but because of their elongated skull and dorsal nos- 
trils (Fig. 3, no), their relationship to Ptyctodontida will be 
questioned, particularly by those who belie\e the ptyctodonts 
were ancestral to chimaeroids. However, it must be pointed out 
that nothing is known about the position of the nostrils in ptycto- 
donts. 

The Order Arthrodira is the best known and most varied 
group, including currently 121 genera or 72% of known placo- 
derm genera, yet the classifications that have been proposed for 
it have been largely by level of organization, rather than phylo- 
genetic. This is true of the commonly used major subdivisions, 
the Arctolepida (or Dolichothoraci ) and Brachythoraci (and its 
two subgroups, the Coccosteomorphi and Pachyosteomorphi) . 
It appears to be worthwhile to attempt a phyletic classification, 
even though our incomplete knowledge will make this provisional 
and certainly subject to future corrections and additions. Instead 
of the two to four gradal subdivisions of current usage, the 21 
arthrodiran families are grouped according to their probable 
common ancestry in 8 suborders. 

Figure 5. Cranial and thoracic shields of Placodermi with elongated 
shoulder girles, lateral views except I. A. Order Petalichthyida (Lunaspis 
herohU, after Stensio, 1963) ; B, Suborder Actinolepina (Sigaspis lepidopJiom, 
after Miles, 1973) ; C, Suborder Phlyctaeniina {Phlyctaenius acadica, after 
Heintz. 1934 and ^Vestoll and Miles, 1963) ; D, Suborder Wuttagoonaspina 
(Wiittagoonaspis fletcheri, attempted restoration based on figures of Ritchie, 
1969 and 1973) ; E, Suborder Holonematina {Holoyiema xvestolli, after Miles. 
1971) ; F, Suborder Coccosteina (Coccosteus nispi'datiis, after Miles and 
Westoll, 1968) ; G, Suborder Pachyosteina (Rhinosteus parvulus, after Stensio. 
1963) : H, Suborder Brachydeirina (Leptosteiis hickensis, after Stensio. 
1963) ; I-J, Suborder Heterostiina (Heterostins ingeyjs) ; I. dorsal view of 
cranial and thoracic shields, after Heintz. 1929; J. lateral view of thoracic 
shield, after Heintz, 1929; K, Order Antiarcha (Pterichihyodes milleri, after 
Traquair, 1914) . Adl. anterior dorsolateral plate; Al. anterior lateral plate; 
Amd. anterior median dorsal plate; art, cranio-thoracic joint; Ce, central 
plate; Md, median dorsal plate; ng. nuchal gap; Nu, nuchal plate; or, orbit; 
pa, pectoral appendage; Pdl, posterior dorsolateral plate; pe, pectoral 
emargination; ]:)f, pectoral fenestra; PI, posterior lateral plate; Pmd. pos- 
terior median dorsal plate; Pnu, paranuchal plate; So, suborbital plate; Sp, 
spinal plate. 



1975 



PLACODERM FISHES 



15 



The first suborder to appear and surely the most primitive is 
the Actinolepina (Fig. 5B), with a single family, the Actinolepi- 
dae. It has the elongated thoracic shield that typifies early 
Arthrodira, and it is closed behind the pectoral fins to form 
pectoral fenestrae (Fig. 5B, pf), as is characteristic of primitive 
members of the order. The spinal plates are well de\'eloped and 




16 BREVIORA No. 432 

projecting but not greatly elongated (Fig. 5B, Sp), the pectoral 
fins are narrow-based, the median dorsal short and broad (Fig. 
5B, Md), the endocranium platybasic, the orbits small and an- 
terior, and the rostral region containing the nasal capsules some- 
times separately ossified. All of these characters are primitive 
within Arthrodira, though some are advanced for Placodermi. 
However, Actinolepina are distinguished from other Arthrodira 
by one feature that is clearly derived: there is a sliding joint 
between the cranial and thoracic shields formed by smooth, 
anterior flanges on the anterior dorsolaterals that are overlapped 
by the underside of the paranuchals. No doubt there were a 
number of phyletic Hues within the Actinolepidae ; one of them, 
represented by Baringaspis and Aethaspis, shows a tendency to 
reduce the centrals and elongate the nuchal, sometimes by fusion 
with the postpineal. It is from this line that the Antarctaspidae 
and Phyllolepidae may have been derived. 

Another line retained a typical actinolepid thoracic shield 
with a sliding craniothoracic joint (if Ritchie's 1969 restoration 
is correct), yet modified the cranial roof so greatly that it has 
been placed in its own suborder, the Wuttagoonaspina (Fig. 5D), 
The cranial modifications resulted from great enlargement of 
the nuchal plate and a migration of the eyes backwards. 

Though Miles has recently (1973) expressed a contrary opin- 
ion, it seems probable that in some Actinolepidae the sliding type 
of neck joint evolved into a more complicated and efficient 
ginglymoid articulation, with condyles developed on the anterior 
dorsolaterals and glenoid fossae on the paranuchals. It is the 
acquisition of this joint (Fig. 5C, art) that particularly distin- 
guishes the Phlyctaeniina from their ancestors among the Actino- 
lepina, and the joint is retained, with one exception, in all the 
many descendants of the Phlyctaeniina. The dominant family, 
the Phlyctaeniidae, showed a tendency to elongate the median 
dorsal plate (Fig. 5C, Md), though one genus retained the short, 
broad type of Actinolepidae, and many of the known genera 
became specialized in their excessively long spinal plates (Fig. 
5C, Sp). The Williamsaspidae may be a differently specialized 
side-branch of Phlyctaeniina, but this is uncertain since their 
skull and dorsal part of the thoracic shield is unknown. 

An early and distinctive branch from the Phlyctaeniina is the 
Holonematina with the single family Holonematidae (Fig. 5E). 
Their skulls are distinguished by the large pineal plate lying 



1975 PLACODERM FISHES 17 

between the preorbitals, the orbits that deeply notch the cranial 
roof, and the moderately small, subtriangular nuchal. The tho- 
racic shield remains long or is even lengthened, and retains the 
contacts between the lateral and ventral shields behind the pec- 
toral fins. The anterior laterals (Fig. 5E Al) tend to lengthen, 
crowding the pectoral fins backwards. The posterior laterals are 
large (Fig. 5E, PI), and there is a large anterior medioventral. 
Characteristically the main lateral line extends towards the pos- 
teroventral corner of the anterior dorsolateral and has a strong 
flexure on the posterior dorsolateral. Primitive members of the 
suborder have previously been referred to the Groenlandaspididae 
which, until the recent discoveries of Ritchie (1974), have been 
of uncertain affinities. 

The Suborder Coccosteina (Fig. 5F), the most important 
derivative of the Phlyctaeniina, may be recognized by the nuchal 
plate which is trapezoidal in shape and widened posteriorly, by 
the paranuchals which are narrow posteriorly except for strong 
postnuchal processes, and by the centrals which tend to be 
divided into anterior, lateral and posterior lobes. The orbits 
typically are directed more laterally than in Phlyctaeniidae, and 
the pineal comes to lie posteriorly between the preorbitals. In 
the thoracic shield, the median dorsal, which is primitively rather 
long, tends to be shortened ; the pectoral fenestrae are lengthened 
though usually remain closed posteriorly (Fig. 5F, pf). The 
spinals tend to be reduced (Fig. 5F, Sp), and the ventral shield 
is typically lengthened. These characters are well displayed by 
the Family Coccosteidae, which is also distinguished by the post- 
branchial laminae projecting from the mesial faces of the anterior 
laterals, by the course of the main lateral lines parallel to the 
ventral exposed edges of the anterior dorsolaterals, and by the 
long, slender suborbital processes of the suborbital plates. The 
Gemuendenaspidae show their relationship to the Coccosteina 
in the shape of the dermal bones of the posterior part of the 
cranial roof, but retain a number of primitive characters, such 
as the broad, depressed shield, the long, narrow median dorsal, 
and the short, deep suborbital processes on the suborbital plates. 
The Buchanosteidae also have the characteristic nuchal and 
paranuchal plates of Coccosteina, but show a peculiar mixture 
of primitive and specialized characters: they are primitive in not 
having the rostral capsule fused to the rest of the skull, in the 
forwardly directed orbits, in the short, deep suborbital processes, 
and in the short, wide preorbitals; but they are distinctively spe- 



18 BREVIORA No. 432 

cialized in the long postmarginals, the unusually shaped anterior 
laterals which bend inwards to form postbranchial laminae, and 
in the short, nonprojecting spinals. A specialized family known 
only in the Frasnian, the Pholidosteidae, is distinguished by its 
enlarged eyes and elongated orbitotemporal region, by having 
the cheek bones rigidly sutured to the cranial roof, and by their 
long, laterally projecting spinal plates carried by protruding 
wings of the anterior laterals and anterior ventrolaterals. This 
family must have diverged early from the Coccosteidae before 
the reduction of the spinals. The Homostiidae (including both 
typical Homostiidae and Euleptaspidae) show a relationship to 
the Coccosteina in the characteristically shaped nuchal, para- 
nuchals, and centrals, and their appearance in the Siegenian 
suggests an origin from early members of the suborder. The 
family includes large forms with a broad, depressed head and 
body, and is characterized particularly by the great elongation 
of the bones of the posterior half of the cranial roof. The ad- 
vanced Homostiidae are highly specialized in the dorsal position 
of the eyes and in the great shortening of the thoracic shield, but 
retain some primitive characters such as a narrow nuchal gap 
and tuberculated dermal bones, Finallv, the Rachiosteidae are 
shown to be Coccosteina by the shape and proportions of the 
nuchal, paranuchals and centrals, but have reduced the lateral 
and ventral thoracic shields even more than in some advanced 
Pachyosteina, and have also lost the ornamentation on their 
dermal bones. 

The Pachyosteina (Fig. v5G), the dominant placoderms of the 
Upper Devonian, are probably, though not certainly, a mono- 
phyletic group derived from the Coccosteidae. They are char- 
acterized particularly by a thoracic shield shortened dorsally and 
laterally, anterior laterals reduced ventrally to slender bones 
(Fig. 5G, Al), reduced or lost spinals, and pectoral fenestrae 
opened behind so that the bases of the pectoral fins could be 
lengthened. These trends were initiated in their coccosteid an- 
cestors and are paralleled in some specialized families of Cocco- 
steina. They differ from Coccosteina in having the posterior 
margin of the skull roof embayed, in the wider nuchal gap be- 
tween the cranial and thoracic shields (Fig. 5G, ng), in the 
shorter nuchal plate with a pointed or rounded anterior margin 
and a concave posterior margin, and generally in the absence of 
prominent lobes on the central plates. They also show a tendency 
to lose tuberculation on the dermal bones. 



1975 PLACODERM FISHES 19 

Manv Pachyosteina retain primitive, coccosteid-like characters 
among which are small orbits, long, loosely attached cheeks, a 
small nuchal gap, a relatively long median dorsal, rudimentary 
spinal plates, and tuberculated dermal bones. Another primitive 
character is an anteroventrally sloping neck-slit between the head 
and thoracic shield. This sloping neck-slit is retained by the 
Selenosteidae (Fig. 5G) which indicates that they were an early 
side-branch of the suborder, even though they do not appear 
until the Upper Frasnian. In many other respects the family was 
highly specialized, especially in the weak jaws, and in the orbits 
which had enlarged so much that the marginal plates formed 
their posterior boundaries and the cheeks were greatly shortened. 

The Bungartiidae (new family), known only from a single 
Upper Famennian genus, Bungartius, is another family that 
retains the sloping neck-sHt, but is pecuHarly specialized in other 
ways. The preorbital part of the skull is greatly elongate, the 
nuchal gap is much enlarged due to the posterior projection of 
the paranuchal plates, and the jaws are shearing. 

The Mylostomatidae are among the most specialized of Ar- 
throdira with their durophagous jaws and their short, broad, flat 
shield. Their origin is obscure; they show some resemblances to 
Selenosteidae, but if Tafilalichthys is correctly referred here, it 
is possible that they were independently derived from primitive 
Pachyosteina. 

Three families of Pachyosteina are distinguished by having the 
cheeks and gill covers extended posteriorly, resulting in a nearly 
vertical neck-slit. This may also give rise to a sharp angulation 
in the anterior lateral plates where they bend around and under 
the posterior edges of the gill covers. The first to appear, and in 
fact the earliest Pachyosteina, are the Dinichthyidae, which are 
mostly very large, broad-skulled forms with powerful, trenchant 
jaws bearing strong anterior cusps on the anterior supragnathals 
and infragnathals. The Leiosteidae are smaller forms with nar- 
rower skulls that are deeply embayed behind, and with crushing 
jaws. The third family, the Trematosteidae, has rather large 
orbits, long preorbital and short central plates, a postpineal fen- 
estra, strong shearing jaws, and a tendency to deepen the cheeks 
and lower the jaw articulations. They are possibly related to 
Leiosteidae, but could not have been derived from known genera. 

The last family referred to the Pachyosteina is the Titanich- 
thyidae, which were highly specialized giants known only from 
the Famennian. Their shield is broad and depressed, and their 



20 BREVIORA No. 432 

jaws are long and slender, without teeth, cusps or shearing edges. 
Their origin is obscure but possibly lies in the primitive Dinich- 
thyidae. 

The two remaining suborders of Arthrodira include forms that 
have generally been referred to Brachythoraci or Pachyosteo- 
morphi. The Heterostiina, including the single family Hetero- 
stiidae (Fig. 5I-J), would at first sight appear to belong to 
Pachyosteina. Like the Homostiidae and Titanichthyidae, it in- 
cludes large forms with a broad, depressed head and body, but 
is distinguished by a characteristic posterior widening of the 
cranial roof. The latest forms have a very short thoracic shield 
(Fig. 5J) in which the anterior laterals send a long, tusklike 
process to meet the ventral shield, the latter a single plate lying 
far anterior under the head. Since the Heterostiidae occur in 
the Middle Devonian, it is not surprising to find that they retain 
a number of primitive characters. Among these are a relatively 
unspecialized cranial roof, a small nuchal gap, small anteriorly 
placed orbits that face anterolaterally (Fig. 51, or), suborbital 
plates with short suborbital processes and long blades, and tuber- 
culated dermal bones. However, in spite of their early appear- 
ance, they show no coccosteid characters and this, together with 
their phlyctaeniid orbits and suborbital plates, suggests for them 
a precoccosteid origin. If this is true, they are parallel to Pachyo- 
steina, and thus referable to their own suborder. 

The last suborder, the Brachydeirina (Fig. 5H), includes four 
genera grouped in two families, the Leptosteidae and Brachy- 
deiridae, though the three genera of the second family are so 
distinctively specialized that each is commonly placed in a family 
of its own. In contrast to all other Arthrodira, the head and 
body are laterally compressed, high and elongate. In contrast 
to Pachyosteina, the lateral walls of the thoracic shield are not 
greatly reduced and large posterior laterals and posterior dorso- 
laterals are retained (Fig. 5H, PI, Pdl). In spite of the long 
thoracic shield, deep pectoral emarginations (Fig. 5H, pe) sep- 
arate the lateral and ventral shields except anteriorly, indicating 
probably that the pectoral fins were long-based. The nuchal 
gap is never enlarged and in one genus, Synauchenia, the cranial 
and thoracic shields have become sutured together, eliminating 
the neck joint completely. The Leptosteidae (Fig. 5H) have 
smaller orbits bounded posteriorly by postorbitals and suborbitals, 
and a very long, slender thoracic shield. The Brachydeiridae 
have larger orbits bounded posteriorly by marginals, and a 



1975 PLACODERM FISHES 21 

shorter thoracic shield in which the ventral part may be reduced. 
The long thoracic shield of Brachydeirina indicates a derivation 
from a very primitive Coccosteina or perhaps even from one of 
the Phlyctaeniidae. 

The last order, the Antiarcha (Fig. 5K), includes probably 
the most highly specialized of Placodermi. The thoracic shield 
is greatly elongated and has incorporated a second median dorsal 
plate (Fig. 5K, Pmd) behind the anterior one. Instead of pec- 
toral fins, they have peculiar, usually jointed appendages, cov- 
ered with small dermal plates (Fig. 5K, pa). Though often 
considered to be modified fins, these appendages were more 
probably derived from arthrodiran spinal plates. Their skulls, 
with their dorsal eyes and nostrils and large anterior premedian 
plate, are so modified that it is difficult to compare them with 
those of Arthrodira. Although antiarchs have been reported in 
China from beds that are supposed to be Lower Devonian, their 
first certain record is Eifelian. The first to appear are typical 
members of the order and so there are no intermediate forms to 
relate them to more typical placoderms. The elongate thoracic 
shield suggests an origin from primitive Arthrodira, and since 
their exoskeletal craniothoracic joint was certainly independendv 
acquired, their ancestors probably are to be sought among 
Actinolepidae. 



22 BREVIORA No. 432 

LITERATURE CITED 

Gross, W. 1954. /iir Phylogenie des Schultergiirtels. Pal. Zeit., 28: 20-40. 

. 1959. Arthrodiren aus dem Obersilur der Prager Mulde. 

Palaeoiuogr., Abt. A, 113: 1-35. 

1962. Neuuntersuchung der Stensioellida (Arthrodira, Unter- 



devon) . Notizbl. Hessischen Landesamtes f. Bodenfoischung, 90: 48-86. 
1963. Gemuendina stuertzi Traquair. Neuuntersuchung. 



Notizbl. Hessischen Landesamtes £. Bodenforschung, 91: 36-73. 
Miles, R. 1967. The cervical joint and some aspects of the origin of the 

Placodermi. Colloq. Intemat. Cent. Nation. Recherch. Sci., 163: 4f^71. 
. 1969. Features of placoderm diversification and the evolution 

of the arthrodire feeding mechanism. Trans. Roy. Soc. Edinburgh, 68: 

23-170. 
. 1973. An actinolepid arthrodire from the Lower Devonian 



Peel Sound formation, Prince of Wales Island. Palaeontogr., Abt. A, 

143: 109-118. 
0RVIG, T. 1957. Notes on some Paleozoic lower vertebrates from Spits- 
bergen and North America. Norsk Geol. Tidsskr., 37: 285-353. 
Parrington, F. R. 1949. A theory of the relations of lateral lines tO) dermal 

bones. Proc. Zool. Soc. London, 119: 65-78. 
Ritchie, A. 1969. Ancient fish of Australia. Australian Nat. Hist., 16(7): 

218-223. 
. 1974. From Greenland's icy mountains ... A detective 

story in stone. Australian Nat. Hist.. 18(1): 28-35. 
Stensio, E. 1969-1971. Anatomic des Arthrodires dans leur cadre systema- 

tique. Ann. Paleont., Vertebres, 55: 151-192; 57: 45-83, 158-186. 
Westoll, T. S. 1945. The paired fins of placoderms. Trans. Roy. Soc. 

Edinburgh, 61: 381-398. 



1975 PLACODERM FISHES 23 

APPENDIX ~ CLASSIFICATION OF PLACODERMI 

Class Pisces 

Subclass Placoclcrmi 

Order Stensioellida l-'ainily SLensioellidac 

Order Rhenanida Family Asterosteidae 

Order Pseudopetalichthyida Family Paraplesiobatidae 

Order Ptyctodontida Family Ptyctodontidae 

Order Acanthothoraci Family Palaeacanthaspidae 

Family Radotinidae 
Family Kolymaspidae 

Order Petalichthyida Family Macropetalichthyidae 

Order Arthrodira 

Suborder Actinolepina nov Family Actinolepidae 

Suborder Wuttagoonaspina Family Wuttagoonaspidae 

Suborder Phlyctaeniina Family Phlyctaeniidae 

Family Williamsaspidae 

Suborder Holonematina Family Holonematidae 

(including Groenlandaspididae) 

Suborder Coccosteina Family Gemuendenaspidae 

Family Buchanosteidae 
Family Coccosteidae 
Family Pholidosteidae 
Family Homostiidae 

(including Euleptaspidae) 
Family Rachiosteidae 

Suborder Pachyosteina Family Dinichthyidae 

Family Titanichthyidae 
Family Leiosteidae 
Family Trematosteidae 
Family Mylostomatidae 
Family Selenosteidae 
Family Bungartiidae nov. 

Suborder Heterostiina Family Heterostiidae 

Suborder Brachydeirina nov Family Brachydeiridae 

Family Leptosteidae 

Order Phyllolepida 

Suborder Antarctaspina Family Antarctaspidae 

Suborder Phyllolepina Family Phyllolepidae 

Order Antiarcha Family Bothriolepididae 

Family Asterolepidae 
Family Sinolepidae 



24 BREVIORA No. 432 



Figure 6, Phylogenetic chart of Placodermi. Each branch represents a 
family except in Acanthothoraci which includes three families. The width 
of the branches is determined by the number of genera. — > 



ANTI- PHYLLO- 
ARCHA LEPIDA 



ARTHRODIRA 



Pachyosteina 




[\A 



APR 2 1 1977 

MARVARO 
UNI\AERSiT\ 



B R E V I W'K 

Museum of Comparative Zoology 



us ISSN 0006-9698 



Cambridge, Mass. 19 September 1975 Number 433 

SOUTH AMERICAN A NOUS: 
ANOLIS IB AGUE. NEW SPECIES OF THE 
PENTAPRION GROUP FROM COLOMBIA 

Ernest E. Williams^ 

Abstract. Anolis ihague, new species, is described on the basis of a single 
juvenile female. It is regarded as a distinctive peripheral member of the 
Anolis pentaprion group. 

In a series of Anolis antonii received from the Vienna Museum 
is a single small female anole with quite distinctive head and 
dorsal scalation. It is clearly new and I name it after the locality 
at which it was collected : 

Anolis ibague, new species 

Holotype: Vienna 18942:38; a juvenile female. 
Type locality: Ibague, Dto Tolima, Colombia. 

Head. Head scales smooth, imbricate, those in frontal depres- 
sion larger than any on the snout. Scales across snout between 
second canthals 8. 8 scales border rostral posteriorly. Anterior 
and inferior nasal scales in contact with rostral. Six swollen but 
narrow scales between supranasals. 

Scales of supraorbital semicircles very broadly in contact, all 
very large, the second and third pair relatively larger, the third 
pair in contact with the enormous interparietal. Scales of supra- 
ocular disk about 16 in number, smooth, in contact with supra- 
orbital semicircles. Supraciliaries elongate, single, followed by 
granular scales. Six canthal scales, canthus falling well short of 
nostril, separated by swollen subgranular scales. Five loreal rows, 

iMuseum of Comparative Zoology, Harvard University, Cambridge, Mas- 
sachusetts 02138. 



2 BREvioRA No. 433 

uppermost and lowermost largest. Temporal and supratemporal 
scales subgranular, not swollen. No differentiated supratemporal 
line. Supratemporal scales gradually enlarging toward the inter- 
parietal, with the scales immediately lateral and anterolateral to 
the interparietal very large. One row of large scales posterior to 
the interparietal immediately followed by scales similar to those 
of the back. 

Suboculars in contact with supralabials. 6-7 supralabials to 
the center of the eve. 

Mental wider than long, in contact with only two small scales 
between the very large sublabials. Four sublabials on each side 
in contact with the infralabials. 

Throat and anterior chin scales between the sublabials laterally 
large, becoming smaller centrally and posteriorly. 

Trunk. Middorsal scales slightly larger than the lateral gran- 
ules. Lateral granules becoming larger, merging into the much 
larger smooth and imbricate ventrals. 

Dewlap (juv. $). Absent. The merest indication in a very 
small central fold, the scales not enlarged. 

Limbs and digits. Scales of upper afm, front of thigh and 
lower leg smooth. Those of lower affti unicarinate. Those of 
digits weakly multicarinate. 19 lamellae under phalanges ii and 
iii of 4th toe. 

Tail. Compressed. No enlarg&d postanals. No tail crest, a 
double line of weakly keeled scales middorsally. Most ventral 
tail scales more distinctly keeled but scales immediately behind 
vent smooth. 

Color. A white middorsal zone diminishing to a point on the 
occiput but continuing on tail. Head dark, vaguely marked with 
lighter. Flanks light purpHsh, spotted and flecked with darker 
purple. Belly and throat lighter, the throat spotted, the belly 
more indistinctly tinged with darker. 

COMPARISONS 

The affinities of Anolis ibague would appear to lie with those 
beta anoles with smooth ventrals, suboculars in contact with 
supralabials and counts of fourth toe lamellae between 15 and 20. 

On th^ one hand this would appear to ally ibague with the 
fuscoauratus complex, and it is in fact sympatric, perhaps syn- 
topic, with one member of this series-^ — antonii. Not surprisingly, 
A. ibague more closely resembles a species not sympatric with it, 



1975 ANOLIS IBAGUE 3 

A. orton'u a species widely distributed throughout Amazonia. A. 
ortoni approaches A. ibague in its large interparietal and its su- 
praorbital semicircles in contact. It differs in having small scales, 
like those of the dorsum, behind the interparietal. A. ortoni 
resembles A. ibague in the presence of a middorsal light stripe 
in the female. (This, however, is a character frequently present 
in female anoles, even in very distantly related species. ) It differs 
in a tendency to a higher number of loreal rows and in having 
the scales immediately behind the interparietal small like the 
dorsals. Neither the resemblances nor the differences are unique 
or special. 

There appear to be greater resemblances to the pentaprion 
group which has now been described in some detail by C. W. 
Myers (1971) with the description of two new species and the 
restoration from synonymy of a third. 

Myers has defined the pentaprion group in the following terms: 
"Beta anoles of small to moderately large size, relatively short 
legs (appressed hind limbs usually failing to reach ear, never 
reaching eye) ; digital pads dilated, with distal phalanx raised 
from the dilated pad; low loreal region (maximum of 2-5 hori- 
zontal scale rows) ; black throat lining and parietal peritoneum; 
a bluish gray or blue-covered sliver of tissue at the corner of the 
mouth; few rows of scales on dewlap of relatively persistent (i.e. 
fade resistant in preservative) red or purple coloration; tendency 
for lichenose or fungous color pattern (in two of three species) ; 
no vertebral stripe; tendency for smooth scales over most of the 
head and body; relatively small dorsal and ventral trunk gran- 
ules; ventral granules tending to obliquely conical (ontogenetic 
change to flat and imbricate in one species)." 

Some of these characters cannot be determined in the unique 
preserved type, and others do not apply. However, Myers has 
already been forced to acknowledge occasional exceptions to his 
character list, and some characters such as the absence of a verte- 
bral stripe in the female are the sort of characters that are pro- 
visionally accepted as part of a group definition in a small sample 
of species but are discarded without hesitation if the ensemble of 
characters proves that a species belongs in a group. The Hght 
vertebral streak has apparently been evolved many times within 
the genus Anolis, and its appearance in yet another species, what- 
ever its relationships, causes no surprise. 

I would place especial reliance on some of Myers' characters 
and add certain others. Thus, smooth scales on head and body 



4 BREVIORA No. 433 

are at one end of a spectrum that in the genus as a whole varies 
from completely smooth to rugose and heavily keeled. In any 
small set of closely related species, smooth scales are likely to be 
consistent. Similarly likely to be good group characters are low 
loreal counts (lower than 6) and short limbs. 

Quite as useful — ordinarily — are contact between suboculars 
and supralabials and low counts across the snout between pos- 
terior canthals (<10). In some species there is considerable 
variability in these regards; more often these two conditions are 
reliable group characters. 

In these features in which I would place considerable confi- 
dence — they are more distinctive within the beta section of 
Anolis than in alphas — A. ibague fits the pentaprion group. 

DISCUSSION 

The single individual described above seems to be a juvenile 
female. As such it will not appear to be the best material on 
which to base a new taxon. Barbour (1934) has commented: 
"It is most unfortunate to describe Anolis from single female 
specimens as also Boulenger did on all too many occasions." 

Barbour's philosophy, widely shared, rests upon the general 
proposition that male Anolis are often more distinctive in both 
scale and color characters than females of their species. This is 
undoubtedly true. Underwood and Williams (1959), speaking 
of Jamaican anoles, said: "The males of the various forms are 
far more clearly differentiated than the females. The possession 
of a fan by the male contributes to this, but the color of pattern 
of the males is always more distinctive. In some cases females 
are almost impossible to distinguish . . . Descriptions of species 
founded only on female material are of limited value." 

Again the truth of this for Jamaican animals would be difficult 
to deny, but they represent a small radiation that, despite sig- 
nificant differences in ecology and size, is still remarkably close 
knit. In similar mini-radiations of anoles it is often true that the 
color patterns and the spectacular dewlaps of males may be, like 
the voices of male frogs, the major way in which the species tell 
themselves apart. 

However, in this, as in so many cases, no rigid rules apply. 
The \'ariability of each group and subgroup is peculiar to itself 
alone and must be empirically determined. Males are in anoles 
the sex of choice for species descriptions, but sex dimorphism in 



1975 ANOLIS IBAGUE 5 

anoles does not go so far that valid species cannot be recognized 
on females alone. Sexual dimorphism in Anolis is most often 
evident in color and size, much more rarely in the general char- 
acters of scalation. Aspects of morphology most probably asso- 
ciated with social interaction and display — dewlaps, the pro- 
bosci of proboscis anoles, tail crests, etc. ■ — are apt to be sexually 
dimorphic. Sometimes there may be differences in head scales 
but these are minor, e.g., greater keeling of all head scales in 
females than in males, as in females of the Anolis homolechis 
series of Cuba. In no case are scale differences of the kind that 
would permit belief that male and female are quite distinct spe- 
cies; at most they are differences of the kind that could be ex- 
pected to occur between males of very closely related, doubtfully 
distinct species. 

Color differences are often more radical, but here in anoles 
sharp differences may occur as morphs within well-understood 
species or even, not at all unusually, between phases in the same 
individual. 

In any case, the problem of Anolis ibague is not that it is 
rather characterless or differs only in subtleties from any other 
anole. On the contrary, its characters are extreme for its group 
and relati\'ely extreme within anoles. 

The characters of A. ibague that are extreme are the great 
size of the interparietal, of certain of the supraorbital scales, and 
of the sublabials. 

The size of these scales in the juvenile type specimen may well 
be more extreme than in adults of the species. Some head scales 
are often relatively larger in very young specimens of any species. 
But, although the enlargement of certain head scales is greater in 
ibague than in any related species, and these scales are at one 
end of the curve of head scale variation for the genus Anolis as a 
whole, they are, however, nearer the taxonomic norm for such 
iguanid genera as sceloporines or tropidurines, for which a huge 
interparietal and large supraorbital scales are in fact partly diag- 
nostic. There is nothing anomalous about these conditions: they 
are merely highly derived character states. 

The discussion of relationship above has suggested that ibague 
is a local representative in central Colombia of a group — the 
pentaprion group — otherwise unknown there. Special peculi- 
arity in a peripheral isolate is not unusual ; it seems the preferable 
explanation of the exceptional features of this species. 



BREVIORA 



No. 433 



// 

1 1 
1 1 
1 1 

I ( 

I I 
1 1 

!' 

1« 
ll 




/ 

a 

ll 
II 
ll 



ll 

ll 
n 
V 



•4—1 
•4-) 

o 






!h 
(U 

4-) 

a; 

h 

lb 
s 

bo 
« 



o 






1975 



ANOLIS IBAGUE 




Fig. 2. Anolis ibague Type. Dorsal view of head scales. 




Fig. 3. Anolis ibague Type. Lateral view of head scales. 



8 



BREVIORA 



No. 433 




Fig. 4. Anolis ibague Type. Ventral view of chin scales. 



1975 



ANOLIS IBAGUE 




10 



O^ 



-^10' 



Fig. 5. Asterisk indicates type locality of A. ibagiie. 



10 BREvioRA No. 433 

Table 1, Scale characters of A. ibague compared. 

ihague sulci frons fungosiis vociferans pentaprion 



scales across snout 


10 


8 


7 


7-13 


7-14 


scales between semicircles 








1-2 


0-2 


0-2 


loreal rows 


5 


5 


3 


3-5 


2-5 


interparietal/ear 


> 


> 


> 


> 


> 



scales between interparietal 

and semicircles 1 1-3 2 1-3 

scales between suboculars 



and supralabials 














supralabials to center of eye 6 


6 


7-8 


6-8 


7-10 


fourth toe lamellae 17 


18 


17 


18 


19-24 



ACKNOWLEDGMENTS 

The study of South American anoles of which this is a part 
has been supported by National Science Foundation Grant GB 
3 7 73 IX and previous grants. Dr. Joseph Eiselt of the Vienna 
Museum generously loaned the material in which A. ihague 
was discovered. 

LITERATURE CITED 

I 

Barbour, T. 1934. The anoles II. The mainland species from Mexico 

southward. Bull. Mus. Comp. Zool. 77: 119-155. 
MvERS, C. W. 1971. Central American lizards related to Anolis pentaprion: 

Two new species from the Cordillera de Talamanca. Amer. Mus. Novi- 

tates No. 2471: 1-40. 
Underwood, G. and E. E. Williams. 1959. The anoline lizards of Jamaica. 

Bull. Inst. Jamaica Sci. Ser. No. 9: 1-48. 



APR 2 1 1977 

B R E V I W-A 

"Miiseiim of Comparative Zoology 

us ISSN 0006-9698 



Cambridge, Mass. 19 September 1975 Number 434 



SOUTH AMERICAN ANOLIS: 

AN O LIS PARI LIS, NEW SPECIES, 

NEAR A. MIR US WILLIAMS 

Ernest E. Williams^ 

Abstract. Anolis parilis is described as the west Ecuadorian representa- 
tive of A. minis from the Rio San Juan, Colombia, A. parilis differs from 
A. mirus in a number of ways, all individually minor, but sufficient in sum 
to indicate species status. 

The species Anolis mirus was described (Williams, 1963) 
from a single specimen with the imprecise locality "Rio San 
Juan Colombia." No further specimens have been collected in 
the intervening years. 

However, another single specimen, obviously related, has come 
to hand from intermediate elevations in Ecuador. Despite its 
closeness to A. mirus, even in characters quite special to that 
species, it appears to differ enough to deserve description as a 
new species which I name because of its similarity as: 

Anolis parilis n. sp. 

Type. UIMNH 82901, an apparently adult male. 

Type locality. Rio Baba, 2.4 km S Sto Domingo de los 
Colorados, Pichincha, Ecuador. George Key, collector. Novem- 
ber, 1965. 

.Diagnosis. Very close to A. mirus but differing in color, in 
smooth rather than keeled ventrals and in other minor scale 
characters. Perhaps also different in size. 

Head. Head scales small, weakly keeled. About 17 scales 
across snout at level of second canthals. Six scales bordering 

^Museum of Comparative Zoology, Harvard University, Cambridge, Mas- 
sachusetts 02138. 



2 BREvioRA No. 434 

rostral posteriorly. Anterior nasal separated from rostral by one 
scale. Seven scales between supranasals. 

At least 4 scales between supraorbital semicircles, the scales of 
which are not much enlarged. Supraocular disk not differen- 
tiated. A short supraciliary on each side followed by granules. 
Canthus distinct, 9 canthal scales, the fourth largest. Seven 
loreal rows below third canthal (2nd canthal behind level of 
loreal rows on the rise of the orbit). Uppermost and lowermost 
loreal rows largest. 

Temporal and supratemporal scales granular. An indistinct 
double line of enlarged granules at margin between supratem- 
poral and temporal areas. Scales around interparietal larger. 
Interparietal about equal to ear opening, separated from supra- 
orbital semicircles by six scales. 

Suboculars narrowly in contact with supralabials, posteriorly 
grading into upper temporal granules, anteriorly separated by 
one scale from canthal ridge. Nine supralabials to below center 
of eye. 

Mentals wider than deep, in contact with eight scales between 
infralabials. No differentiated sublabials. Central throat scales 
smallest, grading laterally into larger distinctly keeled scales. 

Trunk. Two middorsal rows tending, especially on nape, to 
be conical, enlarged, smooth, subimbricate. Ventrals larger than 
dorsals, subquadrate, smooth. 

Dewlap. Large, extending onto first third of belly. Edge 
scales about equal to ventrals. Lateral scales much smaller than 
ventrals, in rows, widely separated by naked skin. Above dewlap 
on sides of neck complex folding between ear and shoulder. 

Limbs and digits. Largest arm and leg scales about equal to 
ventrals and weakly unicarinate except those of elbows and knee 
larger and multicarinate. Supradigital scales multicarinate. Fif- 
teen scales under phalanges ii and iii of fourth toe; distal pha- 
lanx not raised. 

Tail. Compressed, without crest. Dorsalmost scale row sin- 
gle, keeled. Ventralmost scales larger, strongly keeled. Postanals 
irregularly enlarged. 

Color (as preserved). Red-brown with a narrow black mid- 
dorsal line. Black mottling tending to transverse banding on 
side of neck and lower flanks. 

Size. 81 mm, snout-vent length. 

Discussion. The resemblances and differences between A. 
parilis and A. mirus are made clear in Table 1. The differences 



1975 ANOLIS PARILIS 3 

are just sufficient to imply species distinction given that there 
are only two specimens before us. Size appears to differ but it 
is precisely in the larger species of Anolis that there is a long 
period of growth after sexual maturity. The color and pattern 
of the two are radically different as preserv^ed, but neither are 
known from life. It is improbable but not impossible in a genus 
such as Anolis that a difference as great as seen here could exist 
in the color repertoire of a single species. No single one of the 
scale differences — smooth versus keeled ventrals, suboculars in 
contact with supralabials rather than separated by one scale row, 
the greater number of scales across the snout, the different 
rostral-nasal relationship, etc. — are quite outside the possibility 
of intraspecific variation. Taken together, however, they point 
to a high probability of specific difference, i.e., genetic discon- 
tinuitv. 

Nothing is known of the ecology of either of these species. 
The few suggestions that can be made are inferences from struc- 
ture only. The narrow toe pads without a raised anterior margin 
(the condition described as the diagnostic character of the in- 
valid genus Norops) are characteristic of some anoles that are 
not arboreal but are grass or ground dwellers; this is a derived 
condition within anoles that has been evolved repeatedly. Most 
Norops-Yik^ anoles are small (less than 60 mm snout-vent length) , 
but the South American group to which parilis and mirus seem 
to belong — the eulaemus species group — verges on giant size 
(arbitrarily defined for Anolis as 100 mm snout-vent length). 
Within the eulaemus group two subgroups may be distinguished, 
one of which has the toe pads narrow but with a "raised" distal 
edge — the eulaemus group s. str. — and another with the toe 
pads Norops-Yikt. The latter is the subgroup to which parilis 
and mirus belong along with A. aequatorialis (the ecology of 
which again is quite unknown ) . A combination of giant size 
and toe pads that are poorly differentiated would suggest a 
ground dweller. The artist who drew mirus in fact showed the 
animal on a rocky substrate — on no evidence whatever (Fig. 2, 
Williams, 1963). In fact, however, both parilis and mirus have 
the first phalanx of each digit enlarged and strengthened (shown 
well in mirus in Fig. 1, Williams, 1963), a fact that probably 
does imply climbing propensities but with claws not pads. No 
more can be said until observations on the live animals are re- 
ported. 



BREVIORA 



No. 434 















?^ 




llr''^-'- 


> f\ ' iS'tf -■•;■; 






't-.. " --;.-■ 


'- ■) ^.. -■'■%,^y 


|; ,;^:'"_- 










-. . ; 'U-' -i^-", ■'- 


■{; 3^.- 


.;•'.' i-. afc. 


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':"r" i- "<i^: , . -^ 




.fx-: '■■- -ir;' J- 


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\ 

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t\ 
M 



1 1 
' I 







<U 

Oh 
O 



^ 

OJ 






a, 

h 









1975 



ANOLIS PARILIS 




Fig. 2. A. parilis Type. Dorsal view of head scales. 




Fig. 3. A. parilis Type. Lateral view of head scales. 



BREVIORA 



No. 434 




Fig. 4. A. mirus Type. Dorsal view of head scales. 




Fig. 5. A. minis Type. Lateral view of head scales. 



1975 



ANOLIS PARILIS 



60° 




■10 



O' 



h/0' 

Fig. 6. Dark circle = type locality of Anolis mirus. Dark square = type 
locality of Anolis parilis. 

ACKNOWLEDGMENTS 

Description of A. parilis was made possible by the studies of 
South American anoles that continue under National Science 
Foundation Grant GB 3773 IX and previous grants. My thanks 
go also to the authorities at the University of Illinois who made 
the unique type available to me. 



LITERATURE CITED 

Williams, E. E. 1963. Studies on South American anoles. Description of 
Anolis mirus, new species, from Rio San Juan, Colombia, with comment 
on digital dilation and dewlap as generic and specific characters in the 
anoles. Bull. Mus. Comp. Zool. 129: 463-480. 



^ 



BREVIORA 



No. 434 



scales across snout 
rostral/nasal 

scales between supra- 
orbital semicircles 

supraciliaries 



TABLE 1 

Comparison of A. parilis and mirus 

parilis 
17 



one scale between 
nasal and rostral 



one (short) followed 
by granules 



temporal line 

scales around 
interparietal 

rows between inter- 
parietal and semicircles 

rows between suboculars 
and supralabials 

supralabials to center 
of eye 

mental 

scales in contact with 
mental between infra- 
labials 

sul)labials 

dewlap 



a very indistinct 
double line 

gradually larger than 
dorsals or temporals 







wider than deep 



7711 rus 

12 

two scales between nasal 
and rostral 



on one side the same; on the 
other one (short) and 
granules in the middle of the 
supraciliary margin and 
enlarged scales posteriorly 

a triangle of distinctly 
enlarged scales 

abruptly larger than 
dorsals or temporals 



one inteirupted row 



10 
wider than deep 



adhesive pad 



lamellae under 
phalanges ii and iii 
of fourth toe 

snout-vent length 



8 

not dilferentiatcd 

large, scales in weakly 
defined rows, edge 
scales ca = ventrals, 
complex folding be- 
tween ear and shoidder 

not set off from first 
phalanx 
(NoroJ)s condition) 



15 

81 mm 



same 



large, scales in ivell defi7ied 
rows, edge scales ca = 
ventrals, complex folding 
between ear and shoulder 



same 



15 
116 mm 



L^^ 



'^H'imUO. ^ APR211977 

B R E V I O R A 

Mmseiiiii of CoiiiparatiYC Zoology 



us ISSN 0006-9698 



Cambridge, Mass. 8 April 1976 Number 435 

TWO NEW SPECIES OF CHELUS 
(TESTUDINES: PLEURODIRA) 

FROM THE LATE TERTIARY OF 
NORTHERN SOUTH AMERICA 

Roger Conant Wood^ 

Abstract: Two new species of the pleurodiran turtle Chelus are de- 
scribed from the late Tertiary of northern South America. These are the 
first valid extinct species of the genus to be described. Both occur outside 
the present range of the single living species, C. fimhriatus, and neither 
appears to have been directly ancestral to it. Observations on variability 
in a sample of C. fimhriatus shells are recorded to facilitate comparisons with 
the fossils. 

INTRODUCTION 

Of the world's living turtles, the most bizarre in appearance 
is unquestionably the mata-mata, Chelus fimhriatus. Its shell 
is gnarled and serrated, while its broad and extraordinarily flat 
head, festooned weirdly with fleshy tendrils, looks as if it were 
the product of some science fiction writer's fevered imagination. 
This species at present enjoys a widespread distribution through- 
out the Amazon and Orinoco River basins of tropical South 
America. Yet surprisingly little is known about the behavior, 
ecology, or intra- and interpopulational variation of this peculiar 
creature, and virtually nothing is known about its ancestry. 

The purpose of this paper is to put on record two species of 
the genus from Tertiary sediments of northern South America. 
These are the first fossil remains of Chelus well enough pre- 
serv^ed to permit determination of diagnostic characters, and 
knowledge of them provides the first, albeit imperfect, glimpse 
into the evolutionary history of the genus. One of these species, 

iFaculty of Science and Mathematics, Stockton State College, Pomona, N. J. 
08240. 



2 BREVIORA No. 435 

from the late Miocene of Colombia, was discovered during the 
mid-1940's by the late Dr. R. A. Stirton and his associates from 
the University of California Museum of Paleontology and the 
Geological Survey of Colombia. Occasional reference to the 
existence of this material has been made over the years (e.g., 
Royo y Gomez, 1945; Stirton, 1953; Medem, 1968), but until 
now it has not actually been described. Remains of the other 
new species, from beds of Huayquerian age in northern Vene- 
zuela, were collected during the summer of 1972 by the author 
and colleagues from Harvard's Museum of Comparative Zool- 
ogy. 

The following abbreviations are used: 

AMNH - — • American Museum of Natural History 

BMNH — British Museum (Natural History) 

GMB — Museum of the Geological Survey of Colombia, Bogota 

MCNC — Museo de Ciencias Naturales, Caracas 

MCZ — Museum of Comparative Zoology, Harvard University 

MZUSP — Museo do Zoologia, Universidade de Sao Paulo 

PCHP — personal collection, Dr. P. C. H. Pritchard 

UCMP — University of California Museum of Paleontology 

USNM — United States National Museum of Natural History 

CLASSIFICATION AND DESCRIPTION 

Order Testudines 
Suborder Pleurodira 
Family Chelidae 
Genus Chelus 

Chelus colombianus sp. nov. 
Plates 1-3, Figure 1 

Type. UCMP 78762, a nearly complete shell. 

Hypodigm. The type, and GMB 2045 A, an incomplete shell 
lacking part of the right side of the carapace and the anterior 
plastral lobe; GMB 2049, a partial shell, completely disarticu- 
lated; GMB 2446, carapace fragments; GMB 2085, left epi- 
plastron; GMB 2242, left hyoplastron; GMB 2042, GMB 2089, 
and UCMP 38851, neurals; and UCMP 38838, a peripheral; 
all from the vicinity of Villavieja. 

GMB 1844, a left xiphiplastron ; UCMP 39014 and UCMP 
39024, neurals; all from the vicinity of Carmen de Apicala. 

GMB 1885 and GMB 1891, left xiphiplastra ; GMB 1934, 
right hyoplastron; all from the vicinity of Coyaima. 



1976 TWO NEW SPECIES OF CHELUS 3 

GMB unnumbered, posterior left quadrant of a carapace, 
locality unknown. 

Horizon and localities. Villavieja Formation (late Miocene), 
upper Magdalena River Valley, Colombia. 

The specimens making up the hypodigm were collected in 
the vicinity of three settlements, Coyaima, Carmen de Apicala, 
and Villavieja, the majority cotning from the last (see above). 
Stirton (1953) designated the fossil vertebrates from these three 
different localities as, respectively, the Coyaima, Carmen de 
Apicala, and La Venta faunas. The first of these he regarded 
as being of late Oligocene (Colhuehuapian) age while to the 
latter two he assigned a late Miocene date. Subsequently, Fields 
(1957) suggested that the Coyaima fauna was of the same age 
as the others. Bryan Patterson (personal communication) in- 
forms me that he tends to agree with Fields, being unable to 
see anything diagnostically Colhuehuapian in the published 
account of the scanty and fragmentary Coyaima mammalian 
faunule. As regards the hypodigm of the species here described, 
it is not possible to differentiate the few Coyaima fragments 
from the remainder. 

The strata containing these fossils all belong to the Honda 
Group. These rocks have recently been subdivided into two 
for'mations, the lower termed the La Dorada and the upper the 
Villavieja (Wellman, 1970). The vertebrate-bearing sediments 
are apparently confined to the Villavieja Formation (Van 
Houten and Travis, 1968:696). 

Diagnosis. Differing from all other South American chelids in 
having intergular scute withdrawn from anterior margin of 
carapace, and in hexagonal to octagonal shape of intergular; 
seven or eight pairs of scutes (in addition to an unpaired gular) 
on plastron, rather than six pairs; shell between fifty and one 
hundred per cent larger than that of C. fimbriatus; median ridge 
of carapace not increasing in prominence toward posterior end. 

Description. Most of the specimens that I identify as C. colom- 
bianus are isolated shell elements. Owing to the distinctive shell 
morphology of Chelus, however, there is no doubt about the 
propriety of the generic identification. Only two of the speci- 
mens (UCMP 78762 and GMB 2085) actually preserve evi- 
dence of the diagnostic scute position and pattern, but nearly 
all are from large individuals. Because the beds in which they 
were found are all of essentially the same age, there is no reason 
to suspect that more than one species is represented. 



4 BREVIORA No. 435 

Of the type, little is missing except at the anterior margin of 
the anterior plastral lobe. There has been some dorsoventral 
compaction of the shell, which has produced numerous cracks 
in the bone, especially on the carapace. Bone sutures can be 
clearly discerned on the plastron and, to a lesser extent, the 
boundaries of the peripheral bones can be delimited. So badly 
cracked is the central part of the carapace, however, that all 
traces of sutures have been obliterated from this sector. None 
of the other specimens, however, reveal any peculiarities in the 
pattern of bone sutures for this part of the carapace. No grooves 
demarcating the boundaries between adjacent scutes have been 
preserved on the dorsal surface of the carapace of the type, but 
most of the vertebral outlines can be detected in another speci- 
men (GMB 2045 A). No striking differences in vertebral pro- 
portions are evident. The proportions of the midline ridge 
provide the only possibily diagnostic character of the carapace; 
this ridge does not become increasingly prominent toward the 
rear of the shell, as is typically the case in the single living spe- 
cies. This feature by itself, however, would be insufficient to 
persuade me to recognize a new species, particularly in view of 
the fact that the limits of variation in the shell structure of the 
living species are so poorly known. In fact, except for the for- 
tunate circumstance that parts of the anterior plastral lobe have 
been preserved in two specimens (the type and GMB 2085), 
there would be no compelling reason to suspect that the Colom- 
bian fossils represented anything other than overgrown examples 
of C. fimbriatus. 

The scute pattern of the anterior plastral lobe is unique among 
chelonians in that one or two extra pairs of scutes were clearly 
present (Fig. 1). As the standard and heretofore invariable 
number of paired plastral scutes is six, these extra scutes have 
no counterpart elsewhere within the order. ^ The existence of 
these scutes does not seem to represent an abnormality as they 
were clearly present on both of the only two remains of anterior 
plastral lobes in the hypodigm. The derivation of these novel 
scutes is problematical. They may have grown in to fill the void 
left by the intergular scute as it withdrew from the forward edge 
of the plastron. If so, they might be termed the pre- or ante- 

II know, however, of one example of C. fimbriatus (PCHP 38) in which 
the humeral scutes have nearly been fully subdivided into anterior and 
posterior portions (Fig. 2) . Of all the chelonian specimens that have ever 
come to my attention, this is the only one I have seen exhibiting such a 
tendency. Perhaps it is atavistic. 



1976 TWO NEW SPECIES OF CHELUS 5 

gulars. But why supernumerary scutes should develop here in 
the case of C. colombianus but not in the case of the various 
living species of Chelodina, in which the intergular is similarly 
withdrawn, is not readily explicable. The extra pair of scutes 
might equally well have resulted from the anteroposterior sub- 
division of the humeral, pectoral, or abdominal scutes, in which 
case some other name would be more appropriate. Because of 
my uncertainty as to the homologies of the scutes on the front 
half of the plastron, I refrain from proposing a new name for 
the extra pair characteristic of this species. Disagreement about 
the nomenclature for the bones and scutes of chelonian shells is 
already widespread; the publication of almost every new mono- 
graph or book on turtles is usually an occasion for proposing 
a new name for some bone or scute, reviving one long dis- 
regarded, or reshuffling the standard terms to apply to elements 
not previously so named. This unsatisfactory situation can 
hardly be improved by introducing a new name arbitrarily 
assigned to any one of four pairs of scutes on the anterior half 
of the plastron. What is important is not the name of this pair 
of scutes, but their existence. 

Intergular scutes that do not enter into the anterior margin 
of the plastron are found elsewhere among the chelonians only 
in the related genus Chelodina, whose distribution is limited to 
parts of Austraha and New Guinea (Goode, 1967:24, 36). 
Except in occasional specimens of Chelodina siebenrocki (sensu 
Goode, 1967:44), in which the forward tip of the intergular 
may appear truncated by reaching the plastral margin,^ the 
intergular scute is invariably hexagonal in shape. Of the two 
specimens of Chelus colombianus in which the shape of the 
intergular can be determined, one (the type) displays the typical 
hexagonal configuration seen in Chelodina while the other 
(GMB 2085) is octagonal. Apparently the shape of the in- 
tergular in C colombianus was somewhat variable, but in any 
case it differs from that of the living species C. fimbriatus, which 
is also characterized by a variably shaped intergular, but one 
that is usually either triangular or pentagonal (see, for example, 
Schmidt, 1966, fig. 2). The octagonal intergular shape is, to the 
best of my knowledge, unique. The scute furrows radiating out 
toward the margin of the plastron on the specimen having the 
octagonal intergular (GMB 2085) indicate that at least in some 
instances C. colombianus had an eighth pair of plastral scutes, 

iln a series of fifteen specimens examined by my colleague A. Rhodin, 
one exhibited this atypical scute pattern (personal communication) . 



6 BREvioRA No. 435 

again a unique condition among turtles. Clearly the number of 
pairs of supernumerary scutes (one or two) depended on the 
shape of the intergular and likewise was an individually variable 
feature. 

Accurate measurement of overall shell dimensions is possible 
only for the type. But a second, fairly complete and undistorted 
specimen (GMB 2045 A) has been well restored and a reason- 
ably reliable determination of its length and width is obtainable. 
When compared to a sample of shells of C. fimbriatus (Table 1), 
those of C. colombianus are obviously larger. The two measur- 
able shells of the latter species were not exceptional representa- 
tives of the taxon since most of the fragmentary remains included 
in the hypodigm are of more or less the same size as comparable 
parts of the whole shells. Typical adult specimens of C. colom- 
bianus evidently were much larger than are those of its living 
congener. 

Chehis lewisi sp. nov.^ 
Plates 4-5, Figure 3 

Type. MCNC 239, a complete shell. 

Hypodigm. The tvpe, and MCZ 4337 and MCZ 4338, complete 
shells; MCNC 240, a pleural; MCNC 241, posterior half of a 
carapace and plastron; and MCNC 242, a crushed vertebra 
(probably a cervical) associated with a right xiphiplastron. 

Horizon and locality. Urumaco Formation (Huayquerian), 
from several localities in the vicinity of the town of Urumaco, 
northwestern Falcon, Venezuela. 

Specimens were collected at three different localities. The 
type was found just south of the oil pipe line running from 
Punta Gorda to the Paraguana Peninsula, about .6 kilometer 
SW of where this conduit crosses the highway leading westward 
from Urumaco toward Maracaibo (National Route 3). A 
single specimen (MCNC 240) was encountered 3.5 kilometers 
NW of a hill known as El Picacho on the up side of the Chi- 
guaje fault. The remaining material was all confined to a small 
area of exposures .4 kilometer SSW of Cerro Bacunare between 
the Valle de la Paz and Bacunare Faults. 

II take great pleasure in naming this species for my good friend, Arnold 
D. Lewis, not only because he discovered the type specimen, but also in 
recognition of his many and varied contributions to the science of vertebrate 
paleontology over the years. 



1976 TWO NEW SPECIES OF CHELUS 7 

DiagJiosis. Differing from other species of Chelus in marked 
posterior widening of carapace and in square rather than rec- 
tangular shape of the first neural bone. Shell 15 to 20 per cent 
larger than that of adult C. fimbriatus. 

Description. Like most of the vertebrates from the Urumaco 
Formation, the specimens of C. lewisi are covered with a gyp- 
siferous encrustation that has damasfed the bone surface. The 
scute sulci have mostly been obliterated and it is possible to 
determine the full bone suture pattern in the type alone, and 
this only after weeks of painstaking preparation in the labora- 
torv\ Dimensions of the three complete shells are given in 
Table 1. 

The distinctive shape of the carapace leaves no doubt about 
the validity of this taxon. The shells of both of the other species 
of Chelus are parallel-sided or nearly so,^ whereas in all three 
of the complete shells of this species the width increases markedly 
from front to rear. Although each of these shells has undergone 
a varying degree of dorsoventral compaction, with the type 
showing the least amount of crushing, there is no evidence of 
significant lateral deformation and the present outline of the 
carapace is, I think, an accurate reflection of its true propor- 
tions in life. 

The shape of the first neural bone also appears to be a dis- 
tinctive feature of C. lewisi. Its length only slightly exceeds its 
width, and it is subrounded in outline, whereas in C. fimbriatus 
the length of this bone is generally much greater than its width, 
giving it a rectangular appearance (see Table 1 for measure- 
ments). The width/length ratio for C. lewisi (.92) is outside 
the range of values (.52-.84) for my sample of C. fimbriatus 
and well above the mean value (.69) for this species." The six 
succeeding neural bones are indistinguishable from their counter- 
parts in C. fimbriatus. The neurals are arranged in an uninter- 
rupted sequence. Part of the seventh as well as all of the eighth 
pairs of pleurals meet in the midline of the carapace between 
the last neural and the suprapygal. This is the typical condition 

iln some specimens of C. fimbriatus the sides of the carapace are actually 
bowed inwards slightly in the bridge region between the axial and inguinal 
notches. 

20ne specimen in my C. fimbriatus sample (PCHP 39) has a W/L ratio 
of 1.10. I have deliberately excluded this from consideration because its 
first neural has been transversely subdivided, thus resulting in clearly anom- 
alous proportions (Fig. 4) . 



8 BREVIORA No. 435 

in many specimens of C. fimbriatus. Some variation, however, 
does occur in the Hving species ( Table 1 ) . A relatively small 
proportion of the carapaces in my sample (four out of nineteen) 
had eight rather than seven neurals. In all but one of these 
four specimens, the eighth neural abuts directly against the 
suprapygal, thus preventing any of the pleurals from meeting in 
the midline. In one specimen with only seven neurals, the 
neural series also extends continuously from the nuchal to the 
suprapygal so that no pleurals meet in the midline. 

Outlines of three vertebral scute sulci (the second through 
fourth) can be detected on the carapace of the type specimen 
(MCNC 239), but otherwise none have been preserved on this 
or any of the other specimens referred to C. lewisi. The verte- 
brals are all proportionately broader than in a somewhat smaller 
specimen of C. fimbriatus (MCZ 4028; Table 2), but this may 
in part or entirely be due to dorsoventral compaction of the 
fossil, which is most pronounced in the middle of the carapace. 

The smallest of the three shells of C. lewisi is nearly five 
centimeters longer than the largest of the available shells of 
C. fimbriatus, while the largest is slightly more than nine centi- 
meters longer (Table 1). Hence it appears that typical in- 
dividuals of C. lewisi were somewhat larger (15-20 percent) 
than their living congeners. 

Aside from the proportions of the entoplastron, there is 
nothing exceptional about the shape or arrangement of the 
plastral bones. Entoplastral dimensions can only be determined 
for one specimen of C. lewisi, the type. For this individual, the 
greatest width of the entoplastron is only slightly less than its 
midline length, the width/length ratio being .93 (Table 1). Its 
proportions are such that it barely falls within the upper limits 
of the range recorded in Table 1 for similar measurements of 
C. fimbriatus (.50-93). It may be that this bone tended to be 
relatively broader in C. lewisi than in the living species. If so, 
its proportions may prove to be a useful diagnostic character. 
However, until the rans^e of variabilitv in the dimensions of the 
entoplastron of C. lewisi is better known, judgment must be 
reserv^ed regarding its diagnostic utility. 

Another feature that may serve to differentiate C. lewisi from 
C fimbriatus is the extent to which the three anteroposterior 
ridges on the carapace are developed. For all three of the com- 
plete shells of C. lewisi, the median ridge tends to be rather thin 
and only moderately undulating and, to a lesser extent, the same 
seems to be true of the lateral ridges. In the living species, the 



1976 TWO NEW SPECIES OF CHELUS 9 

thicker median ridge becomes increasingly prominent toward 
the rear, whereas this does not appear to be the case for the 
\^enezuelan fossils. These differences may to some degree be 
artifacts resulting from the dorsoventral compaction that all of 
the shells of C. lewisi have undergone. Although I suspect that 
they are indeed real, they are not vital for establishing the valid- 
ity of the new species and therefore have not been mentioned 
in the diagnosis. 

DISCUSSION 

Up to now, the known fossil record for Chelus has been 
almost nonexistent. Although regrettable, this fact is hardly 
surprising, as the fossil record for South American chelids is in 
general abysmal. This rarity is somewhat puzzling, as the re- 
lated pelomedusid turtles, forms that apparently have generally 
similar ecological requirements, are reasonably well represented 
in the vertebrate-bearing fossil deposits of the continent. 

Fossilized remains were first referred to Chelus more than 
eighty years ago; these consisted of two shell fragments from 
the Amazon Basin of Brazil (Barbosa Rodrigues, 1892:48-49 
and plates 12-15). They were recovered from beds that are of 
Pliocene or Pleistocene age along the course of the Rio Purus, 
probably not far downstream from the Peruvian border. The 
museum in which the specimens were apparently deposited no 
longer exists (Patterson, 1936:50) and the present disposition of 
these remains is unknown. Of the two fragments described by 
Barbosa Rodrigues, the more notable is a portion of the left 
xiphiplastron in which the distinctive elongation of the posterior 
tip, so characteristic of Chelus, has been preserved. Attribution 
of the two fragments to this genus was certainly justified. No 
species-specific characters are evident, however, and Barbosa 
Rodrigues showed commendable (and somewhat unusual) re- 
straint for his times by simply designating them as Chelys (sic). 
Unfortunately, these specimens tell us nothing about the evolu- 
tion of the genus, as they cannot be differentiated from compa- 
rable parts of the shell of the living species. 

Subsequently, Wieland (1923:12-14) described a small por- 
tion of a carapace as representing a supposedly new species, 
"Chelys{?) patagonica." This specimen was of uncertain age 
and vague provenance — "Patagonian Tertiary beds (Mio- 
cene?)." Originally catalogued as part of the collections of the 
Peabody Museum of Natural History at Yale University, the 



10 BREVIORA No. 435 

fragment is now e\idently misplaced or lost. Wieland should 
never have formally proposed a name for it. He was actually 
uncertain as to its proper generic allocation, suggesting that it 
might well belong to ''Testudo [Geochelone in current terminol- 
ogy] or its allies," which I suspect might actually be the case 
since tortoise remains have been recovered from the Miocene of 
Patagonia (Simpson, 1942). Nor were any specific characters 
given for "Chelys{?) patagonica," which Wieland stated was 
"... a purely arbitrary name of convenience." By modern 
taxonomic standards it can only be regarded as a nomen nudum 
(see Simpson, 1942:2), and the specimen is of no further in- 
terest to the present study. 

In 1956, while on a paleontological expedition to the upper 
reaches of the Rio Jurua, Dr. L. I. Price of the Geological 
Survey of Brazil discovered a very large plastron as well as a 
quantity of unassociated fragments that are all clearly referable 
to Chelus. These specimens are probably Plio-Pleistocene in 
age. None have so far been formally described, so I am uncer- 
tain whether they possess any distinctive characters other than 
exceptional size. It is possible that these remains represent a 
new species. 

The two new taxa described in this paper represent the first 
valid extinct species of Chelus yet described. (They are also 
among the best preserved fossil chelids of any sort recorded from 
South x\merica.) UnHke the Brazihan fossils mentioned above, 
both occur outside the present range of the living species. 

Chelus at present occupies an enormous expanse of territory 
and yet remains a monotypic genus, much as the side-necked 
turtle Pelomedusa in sub-Saharan Africa. Unfortunately, rela- 
tively little is known about its ecology. Brief anecdotal com- 
ments have occasionally been published, but none of these, to 
my knowledge, are based on detailed or prolonged study of a 
single population or series of populations. The species is ap- 
parently not uniformly abundant throughout its range, nor does 
it appear to be especially common. Instead, populations seem 
to be scattered in ox-bow lakes and swamps along the banks of 
rivers. (This information was gleaned during the course of a 
paleontological expedition to Peru in the summer of 1974. 
Probably the species is distributed in a hke manner throughout 
its range, but I cannot verify this.) Geological and faunal e\7- 
dence associated with the discoveries of C. colombianus indicate 
that the ecology of this species was similar or even identical to 
that of C. fimbriatus. During Miocene times the area covered 



1976 TWO NEW SPECIES OF CHELUS 11 

by the Villavieja Formation was a flood plain through which 
broad ri\'ers and their tributaries meandered. Swamps, mud 
flats, and ox-bow lakes dotted the flood plain, which was peri- 
odically inundated. In general appearance, the area probably 
would not have differed appreciably from the wet, tropical zone 
of the present-day upper Amazon basin (Fields, 1957:279, 
389-393). The habitat of C. lewisi is more difficult to recon- 
struct. This species is part of a fauna that consists predomi- 
nantly of a variety of aquatic reptiles whose remains were buried 
in both continental and near-shore marine deposits (Wood and 
Patterson, 1973:2). Most or possibly all components of the 
fauna, however, were clearly nonmarine forms. Thus, it seems 
likely that lewisi was a nonmarine form, but it is unfortunately 
not possible at present to determine its habitat more precisely. 
Both fossil species of Chelus possess characters that, I think, 
preclude them from the direct ancestry of C. fimbriatus. The 
intergular of fimbriatus borders on the lip of the anterior plas- 
tral lobe, as is the case for most turtles. But the recessed 
intergular scute of colombianus is an atypical chelonian feature, 
seen elsewhere only in certain Australian chelids. Hence, it is 
probably a derived rather than a primitive character for the 
genus. Since it is unlikely that a species with a derived char- 
acter would later revert to the primitive condition, I suspect that 
these species are members of two distinct lineages. Both colom- 
bianus and fimbriatus have a carapace that is essentially parallel- 
sided; because this is characteristic of the oldest known and also 
of the only surviving species of Chelus, it seems to be the typical 
carapace shape for the genus. Thus I suspect that lewisi, with 
its posteriorly flaring carapace, represents a lineage divergent 
from that which gave rise to fimbriatus. Just as in the case of 
colombianus, it seems improbable that, in the course of evolu- 
tion, a parallel-sided ancestral form could give rise to a flare- 
shelled species such as lewisi and then re-evolve the parallel- 
sided shell shape to give rise to the living species. It is con- 
ceivable that colombianus could have been ancestral to lewisi, 
but there are at present no compelling reasons to believe this. 
Whatever the relationships between these two species inay have 
been, it now appears that there must have been a greater species 
diversity within the genus in the past, with several distinct 
lineages evolving in different directions at one time or another, 
only one of which has survived. Although its fossil record is 
still woefully fragmentary, it seems probable that Chelus has 
not always been a monotypic genus. 



12 BREVIORA No. 435 

Part of the problem in dealing with fossil remains of Chelus 
is that so little is known about morphological variation in the 
living species. Certain variable features — the number of neu- 
rals and whether or not pleurals intervene between the last 
neural and the suprapygal — have already been noted. Other 
character variants of potential taxonomic importance also exist, 
notably the scute pattern on the anterior plastral lobe^ and 
possibly also the proportions of the entoplastron. Schmidt (1966) 
has recorded additional ones: color patterns of the shell and 
extremities; shape of the intergular scute; morphology of the 
head; and relative width of the anterior plastral lobe. Accord- 
ing to Schmidt, it is possible to recognize several subspecies of 
C. fimbriatus although he did not formally do so in his paper. 
This was just as well, as his sample was miniscule (five speci- 
mens) and the associated locality data were vague (e.g., "Bra- 
zil?", "Colombia", "Peru"). Nevertheless, it may indeed be 
possible to distinguish valid subspecies using some or all of the 
characters cited above, and perhaps others too. To do so, how- 
ever, would require better collections than exist at present in 
museums, for several reasons. First, population samples from a 
single locality do not seem to exist, so that there is no basis for 
estimating the extent of intrapopulational variability. Second, 
the total number of specimens available for study appears to be 
rather small. And, third, variation in recent shells cannot be 
correlated with different parts of the species' range owing to the 
generally poor locality data associated with most museum speci- 
mens. For instance, ten of the nineteen specimens listed in 
Table 1 were obtained from zoos, identified simply as being from 
"South America," or were accompanied by no locality data 
whatsoever. Several others were labelled as being from the 
vicinity of Leticia or Manaus. These cities (as well as Iquitos) 
have long been the headquarters of professional animal collec- 
tors, and specimens brought to them may actually have been 
found far away. Only two had data good enough to permit 
identification of the river system in which they were captured, 
and even this is not entirely satisfactory as many tributaries of 
the Amazon and Orinoco Rivers are themselves hundreds of 

lEleven of the nineteen specimens of C. fimbriatus recorded in Table 1 
have the intergular completely separating the gulars. In an additional 
sample of eleven specimens, consisting of live individuals, juveniles, or shells 
for which I only have information about the relative positions of the scutes 
on the anterior plastral lobe, nine have the intergular fully intervening 
between the gulars. 



1976 TWO NEW SPECIES OF CHELUS 13 

miles long. Considerable field work will therefore be necessary 
before it will be possible to determine convincingly whether or 
not valid subspecies of C fimbriatus can be distinguished. Such 
field work would also have the added benefit of providing for 
the first time adequate knowledge about the ecology of this 
species. 











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BREVIORA 



No. 435 



TABLE 2 

Dimensions (in centimeters) of the three vertebral scutes 
preserv^ed on the type carapace of Chelus lewisi (MCNC 239) 
compared with those of comparable scutes of a specimen of 
C. fimbriatus (MCZ 4028). 

Specimen number 

Vertebral number 2 

Midline length 8.5 

Greatest width 12.4 

W/L ratio .69 



MCNC 239 




MCZ 4028 


3 4 


2 


3 4 


8.9 8.0 


6.6 


5.9 5.1 


13.1 10.4 


7.1 


6.9 6.3 


1 .68 .77 


.93 


.86 .81 





Figure 1. Scute patterns on the anterior plastral lobes of two specimens 
of Chelus colombianus, GMB 2085 (top) and UCMP 78762 (bottom) . 
Compare with Figure 2 for an example of the typical scute pattern in 
Chelus fimbriatus. The right epiplastron of GMB 2085 has been restored 
as a mirror image of the left side. The specimens are not to the same scale 
but have been drawn so that the entoplastron in each is of the same length. 



1976 



TWO NEW SPECIES OF CHELUS 



17 






Figure 2. The plastron of a typical specimen of Chelus fimbriatus (MCZ 
4028; left) and one (PCHP 38; right) in which the humeral scutes have 
nearly been fully subdivided into anterior and posterior portions. Both 
plastra are drawn to the same midline length. 



18 



BREVIORA 



No. 435 




Figure 3. Sketch of the carapace of Chelus lewisi to show the pattern 
of bone sutures as well as those scute sulci that can be detected. Some 
compensation has been made for distortions resulting from the dorsoventral 
compaction of the specimen (compare with Plate 4) . 



1976 



TWO NEW SPECIES OF CHELUS 



19 




MCZ 4028 




PCHP 39 

' Figure 4. Anterior ends of two recent Chelus fimbriatus carapaces (not 
drawn to same scale) to show typical proportions of the first neural (top) 
and its abnormal subdivision (bottom) . 



20 



BREVIORA 



No. 435 







Plate 1. Carapace of the type specimen of Chelus colombianus (UCMP 
78762) . Its midline length is 54.8 cm. 



1976 



TWO NEW SPECIES OF CHELUS 



21 



, --^ . , \>v^ ; 5"^ - " 




Plate 2. Plastron of the type specimen of Chelus colomhianus (UCMP 
78762) . 



22 



BREVIORA 



No. 435 








Plate 3. Left entoplastron (in external view) of a specimen (GMR 
2085) referred to Chelus colombianus. The scale is in centimeters. 



1976 



TWO NEW SPECIES OF CHELUS 



23 




Plate 4. Carapace of the type specimen of Chelus lewisi (MCNC 239) . 
Its midline length is 45.5 cm. 



24 



BREVIORA 



No. 435 




Plate 5. Plastron of the type specimen of Chelus leivisi (MCNC 239) 



1976 TWO NEW SPECIES OF CHELUS 25 

ACKNOWLEDGMENTS 

My visits to Bogota in 1970 and to Berkeley in 1971 for the 
purpose of studying the Colombian fossils were made possible 
by a grant from the National Geographic Society. Field work 
in Venezuela during the summer of 1972 was made possible by 
National Science Foundation grant no. GB-32489X to Prof. 
Bryan Patterson, and by the cooperation of colleagues at the 
Escuela de Geologia, Universidad Central de Venezuela (espe- 
cially Profesora Lourdes de Gamero) and the Ministerio de 
Minas e Hidrocarburos. Carmen Julia Medina, Kevin Maley, 
and Robert Repenning assisted Arnold D. Lewis in the prepara- 
tion of the Venezuelan specimens of Chelus. For their hospital- 
ity and assistance, I am particularly grateful to Drs. Luis Felipe 
Rincon Saenz and Andres Jimeno Vega, directors, respectively, 
of the Museo Geologico and the Instituto Nacional de Investi- 
gaciones Geologico Mineras, Bogota, Colombia. For access to 
or information about specimens in their care, I am also indebted 
to: A. G. C. Grandison; J. T. Gregory; J. H. Ostrom; L. L 
Price; P. C. H. Pritchard; A. Rhodin; A. F. Stimson; P. E. 
Vanzolini; E. E. Williams; R. Zweifel; and G. Zug. I thank 
Prof. Patterson for critically reviewing this manuscript, A. Cole- 
man for photographs of C. lewisi, and J. T. Gregory for photo- 
graphs of C. colombianus. 



26 BREVIORA No. 435 

REFERENCES CITED 

Barbosa Rodrigues, J. 1892. Les reptiles fossiles de la vallee de I'Amazone. 
Vellosia, 2: 41-56. 

Fields, R. \V. 1957. Hystricomorph rodents from the late Miocene of 
Colombia, South America. Univ. Calif. Publ. Geol. Sci., 32: 273-404. 

GooDE, J. 1967. Freshwater Tortoises of Australia and New Guinea (in 
the Family Chelidae) . Melbourne, Lansdowne Press. 154 pp. 

Medem, F. 1968. El desarrollo de la herpetologia en Colombia. Rev. Acad. 
Colomb. Cien. Exact., Fis., Nat., 13: 149-199. 

Patterson, B. 1936. Caiman latirostris from the Pleistocene of Argentina, 
and a summary of the South American Cenozoic Crocodilia. Herpeto- 
logia, 1: 43-54. 

RoYO Y Gomez, J. 1945. Los vertebrados del Terciario continental Colom- 
biano. Rev. Acad. Colomb. Cien. Exact., Fis., Nat., 4: 496-511. 

ScHMmT, A. A. 1966. Morphologische Unterschiede bei Chelus fimbriatus 
verschiedener Herkunft. Salamandra, 2: 74-78. 

Simpson, G. G. 1942. A Miocene tortoise from Patagonia. Am. Mus. Novit., 
no. 1209: 1-6. 

Stirton, R. a. 1953. Vertebrate paleontology and continental stratigraphy 

in Colombia. Bull. Geol. Soc. Amer., 64: 603-622. 
Van Houten, F. B. and R. B. Travis. 1968. Cenozoic deposits, upper 

Magdalena Valley, Colombia. Bull. Amer. Ass. Pet. Geol., 52: 675-702. 

Wellman, S. S. 1970. Stratigraphy and petrology of the nonmarine Honda 
Group (Miocene) , upper Magdalena Valley, Colombia. Bull. Geol. Soc. 
Amer., 81: 2353-2374. 

VViELAND, G. R. 1923. A new Parana pleuiodiran. Amer. Jour. Sci., (5) , 
5: 1-14. 

Wood, R. C. and B. Patterson. 1973. A fossil trionychid turtle from South 
America. Breviora, no. 405: 1-10. 



o /\(/xl u ur APR 2 11977 






B R E V I O R A^ 

Miuseiim of Comparative Zoology 



us ISSN 0006-9698 



CambridCxE, Mass. 8 April 1976 Number 436 

STUPENDEMYS GEOGRAPHICUS, 
THE WORLD'S LARGEST TURTLE 

Roger Conant Wood^ 

Abstract: Stupendemys geographicus, a gigantic fossil pelomedusid turtle 
from the late Tertiary (Huayquerian) Urumaco Formation of northern 
Venezuela is described. Stupendemys was evidently a highly aquatic form. 
Whether it was a fresh water or marine turtle, however, cannot be determined 
with certainty on the present evidence. One or perhaps even both pairs of 
limbs may have been modified into flippers, and the head may not have 
been fully retractable in the usual pleurodiran manner. Comparisons with 
records of other enormous chelonians reveal that the carapace of Stupen- 
demys is larger than that of any other turtle, fossil or recent. 

INTRODUCTION 

Paleontologists are occasionally fortunate enough to make 
totally unexpected discoveries. Such was the case during the 
summer of 1972, when a Harvard paleontological expedition 
working in late Tertiary deposits of northern Venezuela un- 
earthed the remains of several huge fossil turtles. These cer- 
tainly attained greater size than any other extinct chelonians yet 
known; they also appear to be larger than any living ones and 
hence the largest turtles that ever existed. The purpose of this 
paper is to describe these gargantuan creatures. 

The following abbreviations are used : 
AMNH: American Museum of Natural History, herpetological 

collections 
MCNC: Museo de Ciencias Naturales, Caracas 
MCZ: Museum of Comparative Zoology: (H), herpetological 

collections; (P), paleontological collections 
PU: Geology Museum, Princeton University 

iFaculty of Science and Mathematics, Stockton State College, Pomona, N. J. 
08240. 



2 BREVIORA No. 436 

SYSTEMATICS 

Order Testudines 

Suborder Pleurodira 
Family Pelomedusidae 

Sttipendemys^ gen. nov. 
Plate 1 and Figures 1-3, 5, 6, and 9 

Type species. S. geographicus^ sp. nov. 

Distribution. Huayquerian, Venezuela 

Diagnosis. Shell gigantic; carapace depressed, with irregular 
nodular contours on external surface and deep median notch at 
front; anterior border of nuchal bone thickened and moderately 
to strongly upturned; posterior peripheral bones moderately 
scalloped along margins; neurals arranged in uninterrupted 
sequence, numbers two through six hexagonal, the seventh 
pentagonal. Mesoplastra hexagonal to subcircular, largely con- 
fined to bridge; lateral ends of pectoral-abdominal scute sulci 
terminating just anterior to axial notches of shell. 

Cervical vertebrae (probably seventh and eighth) with saddle- 
shaped articulations; neural arches relatively high in relation 
to anteroposterior lengths of centra; angle of neural arch of 
presumed eighth cervical with horizontal plane greater than in 
any other pelomedusid; articular facets of postzygapophyses of 
both cer\dcals forming acute angle of less than ninety degrees 
with respect to each other; prezygapophyses of presumed eighth 
cervical directed more perpendicularly than in other pelomedu- 
sids; thin, bladelike spine on anterior face of eighth neural arch; 
no ventral keel on eighth centrum. 

Angle of divergence between two ventral processes of scapu- 
locoracoid roughly ninety degrees; ventromedial process of scap- 
ula dorsoventrally flattened; coracoid greatly thickened along 
medial edge; glenoid socket facing forward rather than laterally. 

Humerus squat, massive, lacking ectepicondylar groove of 
foramen; deep bicipital fossa between radial and ulnar articular 
facets on ventral surface; prominent ridge traversing ventral 
surface of shaft from ulnar process to distal end, terminating 

iThe generic name alludes to the astonishing size of this turtle, and the 
species is named in honor of the National Geographic Society in recognition 
of its generous support of my research on turtles. 



1976 world's largest turtle 3 

just above radial condyle; ulnar condyle broadest at anterior 
end; ulnar and radial condyles facing somewhat more ventrally 
than in other pelomedusids; entepicondyle and supinator process 
strongly developed, resulting in distal expansion of humerus 
almost as great as that of proximal end; shaft triangular in 
cross-section rather than circular. 

Femur squat, massive, greatly flattened dorsoventrally ; 
breadth of tibial condyle approximately one-third total length 
of bone. 

Stupendemys geographictis sp. nov. 

Type. MCNC 244, medial portion of the carapace with asso- 
ciated left femur, frag'ments of a scapulocoracoid and a cervical 
vertebra, probably the eighth. 

Hypodigm. The type, and MCZ(P) 4376, much of the cara- 
pace, fragments of the plastron, a cervical vertebra (probably 
the seventh), both scapulocoracoids and a caudal vertebra; 
MCNC 245, a plastron lacking the epiplastra and entoplastron, 
two nearly complete pleurals, several peripherals, and one neu- 
ral, all from the same individual; MCZ(P) 4377, a cervical, 
probably the eighth; and MCZ(P) 4378, a left humerus. 

Horizon and localities. "Capa de huesos" (also known as 
"Capa de tortugas"), upper member of the Urumaco Forma- 
tion, Huayquerian (which is probably of Pliocene age; see, for 
example, Simpson, 1974: 5). 

Outcrops of the Urumaco Formation are restricted to a rela- 
tively small area in the northwestern part of the state of Falcon, 
centering around the now-abandoned El Mamon oil field (lat. 
11°13'N, long. 70°16'W), just north of the town of Urumaco. 
The type was found immediately west of Ouebrado Tio Gre- 
gorio, near its mouth. Other specimens were found as follows: 
MCZ(P) 4376 — one-half km north of Ouebrado Picacho and 
50' m east of the Chiguaje fault; MCZ(P) 4377 — three and 
one-half km north 30° west of El Picacho on the up side of the 
Chiguaje fault; MCZ(P) 4378 — as for the previous specimen, 
but "about 15 m higher in the section; MCNC 245 — three- 
quarters km north of Kilometer 153 on the oil pipeline running 
from Punta Gorda to the Paraguana Peninsula (same locality 
as MCNC 238, a trionychid; Wood and Patterson, 1973). 

Diagnosis. As for the genus. 



4 BREVIORA No. 436 

DESCRIPTION 

Shell. The most complete carapace is that of MCZ(P) 4376 
( Plate 1 ) , which lacks some of the anterior peripherals on the 
right side, as well as peripherals from the bridge region on both 
sides. Scute sulci are deeply impressed onto the external surface 
but, as in many giant chelonians, most of the bone sutures have 
become largely fused and the pattern of these cannot be traced 
with any degree of certainty. The carapace is low-arched in 
the manner typical of aquatic turtles, and its dorsal surface, 
rather than being smooth, is somewhat nodose. There is a 
strong median indentation at the anterior margin of the cara- 
pace that is unique among pelomedusids (and perhaps even 
among turtles in general) in having the bone of this region 
curled up into a thickened, collarlike structure. Posterior to the 
bridges, the peripheral bones have mildly scalloped margins. 
The sacral region of this specimen is fairly well preser\'ed. There 
are four sacral ribs abutting against the attachments of the ilia 
onto the visceral surfaces of the eighth pair of peripherals; the 
distal ends of the last two of these are fused together. This is 
essentially the same pattern as reported by Zangerl ( 1 948 : 
30-31 and pi. 4, fig. 3) for the largest living South American 
pelomedusid, Podocnemis expansa. There is a slight postero- 
medial overlap of the iliac scars onto the suprapygal. Whether 
these also extended forward onto the under surface of the 
seventh pair of pleurals (and if so, to what extent) is uncertain 
because the course of the suture between the seventh and eighth 
pairs of pleurals cannot be determined. Measurements of this 
carapace are given in Table 1. 

The carapace of the type specimen ( Fig. 1 ) differs in several 
respects from that of the one just described and moreover pro- 
vides information about the shape and arrangement of the neu- 
ral bones not revealed by the more complete specimen. Meas- 
urements of the vertebral scutes of the two carapaces (Table 1) 
indicate that the type was somewhat larger, roughly by five 
per cent. Its midline length, therefore, would have been in the 
neighborhood of ten to twelve centimeters longer, giving an 
estimated midline length of as much as 230 centimeters. The 
curling and thickening of bone at the anteromedian indentation 
is less pronounced in the type than in MCZ(P) 4376. The out- 
lines of six neural bones can be traced on this specimen. The 
pattern revealed is typical for South American pelomedusids; 
the last neural, which I believe to be the seventh, is pentagonal 



1976 world's largest turtle 5 

while those anterior to it (presumably the second through sixth) 
are hexagonal. The neurals, again typically, tend to become 
progressively broader in relation to their anteroposterior length 
toward the rear of the series (Table 2). As far as can be de- 
termined, the neurals were arranged in an uninterrupted se- 
quence. Behind the last neural, part of the seventh and all of 
the eighth pair of pleurals meet in the midline. 

An isolated neural bone from another specimen (MCNC 
245 ) adds further information about the structure of the median 
part of the carapace. The bone is hexagonal and somewhat 
longer than broad (Table 2), indicating that it comes from the 
anterior part of the series. Because the first neural of pelomedu- 
sids is usually elongate and rectangular or oval, it seems reason- 
able to assume that the specimen in question is either the second 
or third. The bone was obviously in direct contact with neurals 
both to the front and rear. This reinforces the impression al- 
ready given by the type carapace that the neural series was 
continuous, and, in fact, if the neural is actually the second 
rather than the third, proves the point. A notable feature of 
this neural is its exceptional thickness in proportion to its length 
and width; at various places around the periphery the bone 
measures 2.8, 2.6^ and 2.4 centimeters dorsoventrally. In gen- 
eral, pelomedusid neurals tend to be proportionately much 
thinner. Although it is not feasible to measure the thickness of 
the individual neurals of the type carapace, it is possible to state 
that the carapacial bone does appear to be disproportionately 
thick, even for a turtle of such exceptional size. Perhaps the 
unusual thickness of the shell should be considered a diagnostic 
character of the taxon. 

There is nothing remarkable about the carapace scute pattern 
of S. geographicus. It is virtually indistinguishable from that of 
any of the living South American pelomedusids which, except 
for minor variations, are all very similar. 

No identifiable plastral remains are associated with the type 
specimen. However, the mesoplastra, hyoplastra, and right 
hypoplastron of MCZ(P) 4376 were recovered; these had been 
crushed down into and molded against the shallow bowl-shaped 
depression formed by the visceral surface of the carapace (the 
shell was found lying upside down) and unfortunately preserve 
little in the way of detail. Nevertheless, the presence of meso- 
plastra in conjunction with pelves that were clearly fused to the 
shell leaves no doubt that these gigantic turtles are pelomedusids. 



6 BREvioRA No. 436 

The mesoplastra are relatively small, hexagonal to subcircular 
elements, laterally positioned and confined largely to the bridge. 
This is the standard configuration for all known living and 
fossil South American pelomedusids. On the basis of size and 
thickness, I have referred a fairly complete plastron and some 
miscellaneous carapacial fragments ( MCNC 245 ; Fig. 2 ) to 
Stupendeynys. Although very large by ordinarv' pelomedusid 
standards (Table 3), this plastron is relatively small in com- 
parison to the carapaces described above. Presumably it repre- 
sents a young adult. The forward portion of the anterior lobe is 
missing. This is regrettable because it is this part of the pelo- 
medusid shell that is generalh' the most useful for taxonomic 
purposes. Nevertheless, some interesting characteristics are evi- 
dent. The bridge is considerably longer at its base than the 
posterior plastral lobe (Table 3). The bone is exceptionally 
thick in proportion to its length and breadth. And, most notably, 
the lateral ends of the pectoral-abdominal scute sulci terminate 
just in front of the bases of the shell's axial notches, on the 
edges of the anterior plastral lobe. This position is in contrast 
to other South American fossil and recent pelomedusids in which 
these sulci typically meet marginal scute sulci on the forward 
third of the bridge, usually just in front of the anterior meso- 
plastral bone sutures. The plastral formula, insofar as it can 
be determined, is: femoral > abdominal > anal. 

Axial skeleton. The three cervical vertebrae that have been 
recovered (MCZ[P] 4376, MCZ[P] 4377, and MCNC 244) 
belong to three different individuals and represent only two of 
the eight bones in the series. Measurements of these are given 
in Table 4. Because of the unique morphology of these verte- 
brae, it is difficult to be certain as to their positions in the series. 
In the cervicals of living pelomedusids, the neural arches be- 
come increasingly prominent from front to rear, that of the 
eighth always having the greatest height in relation to the length 
of the centrum (Table 4). The two morphologicallv identical 
fossil cervicals (MCZ[P1 4377 and MCNC 244) have neural 
spines that are, relatively, even more prominent than that of 
the eighth cervical in living pelomedusids, while the third 
(MCZ[P] 4376) has an arch only slightly less prominent 
(Table 4). On this basis it would seem likely that we are 
dealing with cervicals at the posterior end of the series, pre- 
sumably the seventh (MCZ[P] 4376) and eighth (MCZ[P] 
4377 and MCNC 244). 



1976 world's largest turtle 7 

However, examination of the central articulations furnishes 
contradictory evidence. Cervicals four, five, and six of all living 
South American pelomedusids have saddle-shaped articulations, 
the seventh is similarly shaped anteriorly but convex posteriorly, 
and the eighth is concave in front and convex behind (Williams, 
1950: 528, 532, 552, and fig. 11). The three known cervicals 
of Stupendemys have saddle-shaped articulations, and hence 
compare in this feature to the fourth through sixth cervicals of 
the extant South American pelomedusids, rather than to the 
seventh or eighth. (Undescribed fossil pelomedusid cervicals 
from the late Cretaceous of Brazil, which I have been able to 
examine through the courtesy of Dr. L. I. Price, are indistin- 
guishable from those of living South American representatives 
of the family.) In living African pelomedusids, the centra of 
cervicals three through eight are uniformly procoelous (Williams, 
ibid. ) . Cervicals are known for only one African fossil pelo- 
medusid (Wood, 1971), and these differ from both living Afri- 
can and South American forms in having articular surfaces 
intermediate in shape between the saddle joints of the latter and 
the procoelous condition of the former. No cervicals have been 
reported for fossil pelomedusids from continents other than 
Africa and South America, the only regions, together with 
Madagascar, where the family still survives. The cervical artic- 
ulations of Stupendemys are therefore most closely comparable 
to those of its South American relatives. 

Because the trend of anteroposteriorly increasing neural spine 
height seems to be consistent in all pelomedusids, whereas the 
pattern of cervical articulation varies somewhat, I am inclined 
to place more reliance in the former feature as a means for 
determining the relative position of the Stupendemys neck 
vertebrae in the cervical series. As Table 4 shows, the height/ 
length ratio of the eighth cervical is always the greatest for any 
individual. Moreover, as shell size increases, the height/length 
ratio also increases, so that it is greater for the eighth cervical 
of Podocnemis expansa than for that of the much smaller Pelo- 
rhedusa subrufa. Given these observations, and in view of the 
fact that the height/length ratios of MCZ(P) 4376 and MCNC 
244 are considerablv s^reater than those recorded for anv of the 
Recent species, while that of MCZ(P) 4376 is about the same 
as the greatest ratio for the largest Recent specimen measured, 
it seems that the cervicals of Stupendemys are from the pos- 
terior part of the series, probably representing the seventh and 
eighth. 



8 BREvioRA No. 436 

If the cervicals of Stupendemys are, in fact, the seventh and 
eighth, then they are unique among known pelomedusids by 
virtue of their saddle-shaped articulations. There are, in addi- 
tion, several other features of these vertebrae that reinforce this 
impression. One of the most obvious is that the neural arch of 
the eighth cervical of Stupendemys makes a much less acute 
angle with the anteroposterior axis of the centrum than do those 
of the comparable cervical in other pelomedusids. (In the 
cervical series of Recent pelomedusids that I have examined, the 
neural arch of the eighth cervical always makes the greatest 
angle to the horizontal plane.) In posterior view, the articular 
facets of the postzygapophyses form an acute angle of less than 
ninety degrees with each other. Those of other pelomedusids 
are nearly horizontal to the dorsoventral axis of the vertebrae 
(fig. 4; see also WilHams, 1950, fig. 11). Viewed laterally, 
the shafts of the prezygapophyses of the presumed eighth cervi- 
cals of Stupendemys are directed much more perpendicularly 
than those of other pelomedusids. Although impossible to meas- 
ure precisely, the angle made with the horizontal plane in the 
specimens of Stupendemys seems to be roughly sixty to seventy 
degrees, whereas in others it is closer to thirty degrees (cf. 
figs. 3 and 4). The thin, median, bladelike spine on the anterior 
face of the neural arch of the presumed eighth cervical of 
Stupendemys is also unlike anything seen on comparable parts 
of other pelomedusid cervicals. In most pelomedusids, the 
ventral surfaces of the cervical centra are typically bowed up- 
wards, sometimes quite strongly, along the anteroposterior axis. 
The one exception known to me is the eighth cervicals of 
South American representatives of Podocnemis. In these, a flat 
blade of bone projects downward from the ventral surface 
( Fig. 4 ) . But in both examples of the presumed eighth cervical 
of Stupendemys, the ventral surface is neither bowed upwards 
nor downwards; it is, instead, flat. Unfortunately, the bottom of 
the presumed seventh cervical vertebra (MCZ[P] 4376) is too 
badly damaged to determine its original shape. 

A single, small caudal vertebra was found in association with 
one of the shells (MCZ[P] 4376). It is poorly preserved and 
reveals no features of special interest. 

Appendicular skeleton. Much of both scapulocoracoids have 
been preserved for MCZ(P) 4376, as well as fragments of one 
belonging to the type. It is not possible to determine with cer- 
tainty the relative lengths of the three prongs making up the 



1976 world's largest turtle 9 

shoulder girdle. The medial tips of the ventromedial portions 
of the scapulae are broken ofT. The dorsal processes of this 
same bone ha\'e been broken at their bases and flattened into 
the same plane as the other two elements. Since their basal 
contacts have been obliterated, it is impossible to determine how 
much (if any) of these processes is lacking. The coracoids, 
however, appear to be complete. Both the left and right ones 
are of essentially the same lengths in MCZ(P) 4376 and are 
considerably lons^er than what remains of the ventromedial 
processes of the scapula, but slightly shorter than the more 
complete of the two dorsal scapular processes that have been 
preserved ( Table 5 ) . These proportions are in accord with 
those of Recent pelomedusids, in which the ventromedial process 
of the scapula is much shorter than the dorsal one, while the 
coracoid is intermediate in length, generally somewhat flattened 
dorsoventrally, and moderately to greatly expanded towards its 
extremity. Despite this incompleteness a number of distinctive 
features are evident. The glenoid socket faces almost directly 
forward in Stupendemys, whereas in typical pelomedusids it 
tends to face in a lateral direction ( Fig. 5 ) . The angle at which 
the two ventral prongs of the scapulocoracoid diverge is con- 
siderably less acute in Stupendemys than in any other known 
pelomedusid (Fig. 5). The shoulder girdle of Stupendemys 
further differs from those of typical Recent South American 
pelomedusids in that the ventromedial process of the scapula is 
dorsoventrally flattened. In specimens of Podocnemis dumerili- 
ana, P. expansa, and P. unifilis that I have examined, this bone 
is anteroposteriorly flattened. The medial side of the coracoid 
of Stupendemys is greatly thickened. This is not true of the 
coracoids in living xA.frican representatives of the family, which 
are uniformly thin, flat, and greatly expanded. In typical South 
American pelomedusids as well as in Podocnemis madagascarien- 
sis, the coracoid is not so expanded but is transversely arched, 
with the apex of the arch on the dorsal side. (The one excep- 
tion of which I am aware is Podocnemis erythrocephala [Mit- 
t'ermeier and Wilson, 1974]; the coracoid of this species does 
not expand at all towards its tip but remains uniformly oval 
along its entire length [e.g., MCZ(H) 10096].) The coracoid 
of Stupendemys may have been similarly arched, if the dorso- 
ventral crushing of this element is taken into account. The 
thickness of bone along its medial edge, however, still seems to 
set it apart from the other South American forms. The dorsal 
scapular process in Stupendemys appears somewhat flattened, 



10 BREvioRA No. 436 

whereas in Recent pelomedusids it is more oval in cross-section. 
This flatness, however, may result from crushing in the hori- 
zontal plane; because of my uncertainty about this feature I 
have refrained from listing it as a diagnostic character. 

A nearly complete left humerus (MCZ[P] 4378) is all that 
is known of the forelimb. This specimen is of great interest in 
that it is totally unlike the humerus of any other known chelon- 
ian — let alone pelomedusid — living or fossil. The head as 
well as the terminal portions of the radial and ulnar processes 
are missing, but otherwise the bone is complete ( Fig. 6 ) . This 
humerus is extraordinarily massive, with distal and proximal 
ends both markedly expanded, the latter slightly more so than 
the former (see Table 5 for measurements). The curvature of 
the shaft does not appear to differ appreciably from that of 
living pelomedusids. There is no trace of an ectepicondylar 
groove or foramen on the dorsal surface, a feature present in 
all other pelomedusids (and, indeed, chelonians in general). 
Between the radial and ulnar processes, on the ventral side, is a 
very deep, semicircular depression, the bicipital fossa. This is 
more prominent than in the fossil pelomedusid Bothremys 
barberi ( Zangerl, 1 948 : 34 and fig. 1 3 ; Gaffney and Zangerl, 
1968) or Podocnemis but is developed to about the same 
extent as in Pelomedusa or Pelusios. Immediately above the 
articular facets on the ventral surface at the distal end of the 
shaft is a very deep, triangular fossa. This seems to be a natural 
depression rather than the result of poor preservation of the 
bone and has no equivalent, so far as I have been able to de- 
termine, elsewhere within the order. A thick, prominent ridge 
extends transversely across the ventral surface from the base 
of the ulnar process to a point adjacent to the radial condyle. 
Such ridges are absent in living pelomedusids, although less 
pronounced ones have been reported in fossil pelomedusids, 
Bothremys (Zangerl, 1948) and Taphrosphys (Gaffney, 1975; 
Fig. 8, this paper). Typically, the ulnar condyle in pelomedu- 
sids has a spool-shaped outline, equally expanded at both ends. 
The ulnar condyle of Stupendemys, however, is markedly 
broader at its anterior end than at its posterior limit. A further 
distinctive feature of Stupendemys is that the trochlea extends 
farther onto the ventral surface than in other pelomedusids. 
To either side of the trochlea, the supinator process and 
entepicondyle bulge outwards, the latter especially. Only in 
Taphrosphys is the distal end of the humerus expanded to 
such an extent (distal width over total length equals 0.47 in 



1976 world's largest turtle 11 

Taphrosphys [Gaffney, 1975, p. 16], 0.44 in Stupendemys). 
In cross-section, midway between the ends, the shaft is triangular 
rather than circular or oval, as is typically the case for pelo- 
medusids. 

A left femur (Fig. 9) was found associated with the type 
shell. The head and terminal portions of both trochanters are 
missing, as well as some bone from an area at the distal end 
of the dorsal surface. The distal articular surfaces, however, 
have been largely preserved. If complete, the femur would 
have been of essentially the same length as the only known 
humerus (Table 5). Like the humerus, the femur of Stu- 
pendemys is massive. Its shaft is oval in cross-section and 
greatly flattened dorsoventrally. The shaft of Podocnemis ex- 
pansa is also oval in coss-section but is instead flattened antero- 
posteriorly. As for the humerus of Stupendemys, the curvature 
of its femur does not seem to differ significantly from that of 
living pelomedusids. The distal end of the shaft is markedly 
expanded, much more so than in Podocnemis expansa (distal 
width over total length equals 0.47 in Stupendemys, 0.29 in 
P. expansa [MCZ(H) 4469]). 

DISCUSSION 

Stupendemys has many very unusual anatomical features. 
No modern chelonian is at all comparable to it, nor does it 
closely resemble any of the better known fossil turtles. 

Its systematic position, at least, is clear: it is an aberrant 
member of the Pelomedusidae. This is conclusively demonstrated 
by several characters : 1 ) the presence of mesoplastra ; 2 ) fusion 
of the pelvis to carapace and plastron; and 3) shape of the 
cervical articulations. 

It is when one strives to understand Stupendemys as a living 
animal that difficulties arise. In the following pages I attempt 
a functional analysis of the known parts of the skeleton, search- 
ing for clues to behavior and habitat. 

The relatively low-arched carapace of Stupendemys indicates 
that it was almost certainly a highly aquatic form, as are all 
living pelomedusids and most fossil ones. Pelomedusids (not 
yet formally described) from two different African fossil local- 
ities, one of Oligocene and the other of Miocene age, are the 
only terrestrial members of the family yet known (Wood, 1971). 
These forms had extremely high-domed shells, superficially very 
tortoiselike in appearance. Conversely, the only strictly terres- 



12 BREVIORA No. 436 

trial, flat-shelled turtle is the exotic pancake tortoise of East 
Africa, Malacochersus, and its shell structure represents an 
adaptation to most unusual habits. Shell shape thus seems to 
be a nearly infallible indicator as to whether a chelonian was 
aquatic or terrestrial, and Stupendemys clearly falls into the 
former catesrorv. 

The strong median indentation at the front end of the cara- 
pace is not characteristic of pelomedusids in general, but is 
reminiscent of the condition seen in the unrelated, big-headed 
turtle, Platysternon, of southeast Asia. Platysternon has a xtry 
large head in proportion to the size of its shell; consequently, 
indi\iduals of this genus are not able to withdraw their heads 
into the shell in the typical cryptodiran manner. But the an- 
terior embrasure of the carapace provides a notch into which 
the back of the head fits when retracted to the maximum extent 
possible. The heavily boned dorsal roof of the skull then acts, 
in effect, as an anterior continuation of the carapace and evi- 
dently ser^^es as a reasonably efTective deterrent to predators. 
Stupendemys, too, may have had a proportionately large, heavily 
armored skull which did not have to be swung under the cara- 
pace for protection in the usual pleurodiran fashion, but instead 
was simply lodged against its anterior border when danger was 
imminent. 

I cannot readily account for the significance of the thickened, 
curled-up bone at the anterior margin of the carapace. It might 
represent a variably-expressed secondary sexual character if the 
two carapaces in the available sample represent opposite genders. 
It has, so far as I am aware, no structural equivalent elsewhere 
within the order. 

South American pelomedusids are the only chelonians having 
saddle joints on the articular surfaces of their cervical centra 
(Williams, 1950, appendix 1). But, as pointed out (p. 8), 
the cervical vertebrae of Stupendemys, although possessing the 
characteristic saddle joints, are in detail very different from 
those of any pelomedusid known from that continent or else- 
where. This fact supports the supposition that neck retraction 
in the genus was fundamentally different from that of other 
pleurodires. But if, as suggested above, Stupendemys was com- 
parable to Platysternon in its ability to retract its skull only 
partially, then the similarities in behavior were not paralleled 
by structural resemblances of even the most superficial kind. 
The articular surfaces of the fifth throus^h eis^hth cervical centra 
in Platysternon are generally doubled, the centra themselves are 



1976 world's largest turtle 13 

very broad and flat, the neural arches lack spines, and so on. 
In sum, while it is clear that the cervicals of Slupendemys are 
markedly different from those of any other known turtle, the 
significance of these differences is not readily apparent. 

Re2:rettablv, the relative sizes of the humerus and femur in 
Stupendernys cannot be determined with any degree of cer- 
tainty. This is unfortunate because, for turdes in general, the 
proportions of the fore and hind limbs are good indicators of 
the customary mode of progression. Pelomedusids and most 
aquatic cryptodires rely primarily on their hand limbs for pro- 
pulsion while swimming, hence their femora are larger than 
their humeri. But in tortoises and marine turtles, the opposite 
is true. Thus, for example, if it were possible to establish that 
the humerus of Stupendemys was larger than its femur, this 
might be taken as reasonably good presumptive evidence that 
this peculiar pelomedusid swam in a different way from all 
other pelomedusids ^ perhaps even with flipperlike appendages, 
as in the modern marine turtles. But direct comparisons between 
the humerus and femur of a single specimen of Stupendemys are 
impossible. Moreover, the only known humerus of Stupendemys 
was an isolated find, which therefore cannot be tied to sheU size, 
so that even indirect comparisons (in which limb size is related 
to shell length) cannot readily be made. 

Normally, limb structure is also a good index to the loco- 
motory capabilities of turtles. The highly modified, flippered 
forelimbs of marine cryptodires have a humerus that tends to 
be broad, flat, and relatively straight-shafted. In aquatic (or 
largely aquatic) forms, such as the pleurodires and emydines, 
it is much more gracile, ordinarily more or less circular in cross- 
section, and with a moderate curvature of the shaft. Tortoise 
humeri are stout and often have a strongly bowed shaft. The 
humerus of Stupendemys does not fall satisfactorily into any of 
these broad categories. It is considerably more massive even 
than that of a tortoise, fairly straight in the shaft, but more 
circular than flat in cross-section. The heavy ridge across the 
ventral surface of the shaft almost surely provided an increased 
area for the attachment of hypertrophied antebrachial muscula- 
ture. Such muscles would only be required if the distal ex- 
tremity of the forelimb were for some reason disproportionately 
large, as in marine turtles. While admittedly tenuous, this line 
of reasoning leads me to suspect that the foreHmb of Stupen- 
demys was modified into a paddle, a structure highly efficient 
for swimming but ill adapted to a terrestrial existence of any 



14 BREvioRA No. 436 

sort. Gh'en the absence of direct fossil evidence, however, this 
can only be a very tentati\'e suggestion. 

The humerus of the fossil pelomedusid Taphrosphys (Fig. 8; 
Gaffney, 1975, fig. 12) appears to be intermediate in structure 
between that of Stupendemys and those of typical representa- 
tives of the family. Unfortunately, the humerus is the only part 
of the forelimb of Taphrosphys so far known, so that this taxon 
provides no further insight into the structure and function of the 
Stupendemys forelimb. 

Forms intermediate in femoral structure between Stupen- 
demys and the typical pelomedusids (or turtles in general, 
for that matter) do not exist. Had the femur not been found in 
association with pelomedusid shell remains, its familial allocation 
would have been impossible. Differences between the femur of 
Stupendemys and that of a representative pelomedusid [Podoc- 
nemis expansa) hax^e already been enumerated (p. 11). The 
strongly projecting trochanters, broad intertrochanteric fossa and 
flattened shaft of Stupendemys distinguish it readily from both 
marine cryptodires and tortoises, while the massiveness of the 
bone and the broad, flat shaft together differentiate it from that 
of the other aquatic forms. In these characters, in fact, together 
with the relative straightness of the shaft, the femur of Stupen- 
demys is more like the forelimb of marine turtles than anything 
else. For this reason it is tempting to speculate that the hind 
limbs of Stupendemys may have been modified into paddling 
flippers as large as those possibly present on its forelimb. 

In sum, the available anatomical evidence demonstrates that 
Stupendemys was an aquatic form. In all likelihood, one or 
perhaps even both pairs of limbs were modified as flippers. The 
very size of its shell suggests that Stupendemys must have in- 
habited large, permanent bodies of water which it probably left 
only to lay eggs. Among living aquatic turtles in general, the 
larger the species, the less likely it is to come out of the water 
except for nesting. Size alone probably prevented Stupendemys 
from basking along shores. Flippers, if it had them, would have 
made such an undertaking even more awkward. I suspect that 
Stupendemys was largely if not entirely herbivorous, again 
simply because of its size ; all of the largest living turtles - — land 
tortoises as well as the marine forms — are totally ( or nearly 
totally ) herbivorous. 

Geological evidence, although often helpful in attempting to 
determine the habitat of a fossil, is, in the present case, equivo- 
cal. A variety of different facies are represented in the upper 



1976 world's largest turtle 15 

member of the Urumaco Formation, including near-shore ma- 
rine, brackish, and fresh water deposits. Some of these fresh 
water facies consist largely of platy concretion zones, which are 
probably best interpreted as representing small ephemeral ponds. 
Root casts and locally abundant leaf impressions are also char- 
acteristic of these deposits. Mammalian remains (especially very 
large rodents) tend to be more abundant here, as are certain 
of the reptiles (e.g., Chelus, nettosuchids ) . Other fresh water 
deposits probably represent stream channels and, in some cases, 
swampy areas (as evidenced by localized accumulations of veg- 
etable debris). In general, the vertebrate-bearing sediments 
were evidently laid down in a coastal area over which the posi- 
tion of the shoreline fluctuated back and forth repeatedly. 
Stupendemys could thus have been a marine form that washed 
up on a barrier beach or was stranded in the lagoonal waters 
behind one. Or it may have been a fresh water form carried to 
the delta of a large river system and buried there. Since the 
associated fossil fauna has strong Amazonian affinities and is 
deficient in typical marine components, the latter possibility 
seems strong. But all of the largest known aquatic turtles, both 
living and fossil, are marine forms. This fact, coupled with the 
fairly convincing presumptive evidence that a number of other 
fossil pelomedusids were marine forms,^ prevents categorical 
rejection of the idea that Stupendemys may have been a marine 
turtle. 

The largest of the living pelomedusids (all of which are fresh 
water forms) is Podocnemis expansa, which has a wide distribu- 
tion throughout much of the Amazon and Orinoco River basins 
of South America. This species is sexually dimorphic, the fe- 
males growing to much larger adult size than males (Ojasti, 
1971 ). In a large sample taken from the Orinoco River over a 
period of several years, the maximum carapace length for a male 
was 51 centimeters whereas that for a female was 81 centimeters 
(J. Ojasti, personal communication). The largest shell of this 
species yet reported is 82 centimeters long (Williams, 1954: 
293). Presumably this record is of a female, although the sex 
of this particular specimen was not indicated. With the excep- 

Jlncluded among these are several species of Taphrosphys (Schmidt, 1931; 
Gaffney, 1975; Wood, 1975) , Bothremys (Zangerl, 1948; Gaffney and Zangerl, 
1968) , and a generically indeterminate form from Puerto Rico (Wood, 
1972) . All of these were found in near-shore marine sediments, generally 
under circumstances such that tPicy cannot reasonably be regarded as exotic 
elements washed in from a nonmarine environment. 



16 BREVIORA No. 436 

tion of Stupendemys, no known fossil pelomedusids exceed 
Podocnemis expansa in size, nor do representatives of the only 
other known family of side-necked (pleurodiran) turtles, the 
CheHdae, ever approach P. expansa in size. Thus Stupendemys 
is by far the largest pleurodire, living or fossil, yet known. 

A few species of living fresh water cryptodiran turtles attain 
greater carapace lengths than P. expansa, but none are reliably 
known to approach the size of Stupendemys. A length of nearly 
130 centimeters has been recorded for the carapace of the 
Asiatic trionychid Pelochelys bibroni (Pope, 1935). Another 
Asiatic soft-shelled turtle, Chitra indica, is generally believed to 
have a maximum carapace length of approximately 90 centi- 
meters. One unsubstantiated report indicates that Chitra may 
occasionally reach a carapace length of roughly 180 centimeters 
(Pritchard, 1967:211). No other living or ifossil fresh water 
cryptodires as large as either of these recent trionychids are 
known. 

Some other fossil cryptodiran turtles of enormous size have 
been described, but none of these had shells as large as those of 
Stupendemys. Archelon ischyros, from the Cretaceous of North 
America, is the largest of the fossil marine turtles; its straight- 
line carapace length is 193 centimeters (Wieland, 1909), When 
first described, Geochelone atlas (originally and rather appro- 
priately named Colossochelys) was believed to reach twelve feet 
in carapace length (Falconer and Cautley, 1844). This estimate 
was based on composite reconstructions of fragmentary material 
and has subsequently been modified to a maximum of six feet 
(roughly 180 cm; see Lydekker, 1889, and Auffenberg, 1974: 
173). None of the specimens that have since been referred to 
G. atlas, which is now known from the Pleistocene of India, 
Burma, Java, Celebes, and Timor (Hooijer, 1971; Auffenberg, 
ibid.), appears to have reached or exceeded this length. One 
or more species of Geochelone from the Pleistocene of Florida 
and Texas may also have attained similarly gigantic dimensions 
( W. Auffenberg, personal communication ) . However, no tor- 
toises — li\'ing or fossil — ever seem to have grown any larger. 

In fact, of all known turtles, only the anatomically peculiar 
marine turtle Dermochelys coriacea may rival Stupendemys in 
size. Dermochelys, commonly referred to as the leatherback, is 
reputedly the largest of all turtles, living or fossil. x\dults con- 
sistently attain carapace lengths of over 150 centimeters (Pritch- 
ard, 1971 ). In the only large series of measurements ever made, 
involving 1500 mature female specimens encountered laying eggs 



1976 



WORLD S LARGEST TURTLE 



17 



on the beaches of French Guiana over several field seasons, the 
maximum length recorded was 180 centimeters (three individu- 
als; P. C. H. Pritchard, personal communication). Larger speci- 
mens have occasionally been reported, up to a supposed length of 
3.35 meters, but these are unusual and suspect because they are 
probablv based on estimates rather than actual measurements 
(Carr, 1952:446), and, as Brongersma (1968:38-39) has 
noted, estimates of the sizes of free-swinging marine creatures 
generally tend to be greatly exaggerated. Thus, there do not 
seem to be any reliable records of leatherbacks that equal or 
exceed Stupendemys in carapace length. On the average, cer- 
tainly, carapace lengths of Dermochelys are significantly shorter 
than those of Stupendemys. Moreover, if the known specimens 
are typical representatives of Stupendemys, then adult popula- 
tions evidently tended to be significantly larger than those of 
Dermochelys are today. In sum, it is clear that Stupendemys 
is unquestionably larger than any other previously described 
fossil turtle and it also appears to be larger than any living spe- 
cies. Stupendemys, therefore, is the largest turtle that ever lived. 

TABLE 1 

Measurements (in cm) for carapaces of Stupendemys geographiciis. Di- 
mensions are given as straight-line distances rather than over the curvatures 
of the shells, 

MCNC 244 MCZ(P) 4376 



midline length (as preserved) 
total midline length 
maximum width (estimated) 
maximum parasagittal length 

first vertebral 
second vertebral 
third vertebral 



fourth vertebral 



fifth vertebral 





184 


218 




approx. 230 


218 




190-195 


185 




250 


235 


(length 
1 width 


37.1 
approx. 26 


34.5 
approx. 24 


^ength 
i width 


33.5 
36.4 


34.0 

32.7 


(length 


33.3 


32.4 


) width 


39.3 


34.4 


Clength 
J width 


39.3 
approx. 34 


37.8 
28.1 


^ength 
) width 




52.4 
51.7 



18 



BREVIORA 



No. 436 



TABLE 2 

Neural bone measurements (in cm) for specimens of Stupendemys geogra- 
phicus. 

Midline Maximum Width/ 

Specimen No. Neural No. Length Width Length 



MCNC 244 


3 


16.3 


14.8 


.91 


tt 


4 


16.6 


19.2 


1.16 


t* 


5 


15.5 


18.0 


1.16 


*» 


6 


11.7 


19.0 


1.62 


tr 


7 


11.4 


14.9 


1.30 


MCNC 245 


2 or 3 


7.7 


6.5 


.84 



TABLE 3 

Measurements (in cm) of the plastron (MCNC 245) referred to Stupendemys 
geographicus. 



midline length (as preserved) 
total midline length (estimated) 
width at axial notch 
width at inguinal notch 

anteroposterior length of bridge 

midline length of posterior lobe 
parasagittal length of posterior lobe 
(to tips of xiphiplastra) 



Cleft side 
j right side 

fleft side 
) right side 



57.2 

76 

34.0 

35.3 

35.2 

36.2 

21.0 

25.2 

25.5 



1976 



WORLD S LARGEST TURTLE 



19 



TABLE 4 

Measurements (in cm) of the cervical vertebrae of Stupendemys compared 
with those of adult representatives of each of the three living pelomedusid 
genera, (MCZ [H]44G9, Podocnemis expansa; AMNH 10065, Pelusios sub- 
niger; MCZ[H]1 46146, Pelomedusa subrufn) . 

Height of Neural 
Midline No. in Midline Arch Spine above 

Carapace Cervical Length of Base of Posterior Height/ 
Length Series Centrum End of Centrum Length 



Specimen No. 



MCZ(P)4376 


218 


7(?) 


9.0 


13.41 


1.49 


MCZ(P)4377 


? 


8(?) 


9.0 


15.1 


1.67 


MCNC 244 


230 . 


8(?) 


10.8 


18.7 


1.73 


MCZ(H)4469 


72.2 


5 


3.1 


2.8 


0.90 


>> 


>t 


6 


3.5 


3.3 


0.94 


«> 


tt 


7 


3.6 


4.1 


1.14 


»f 


»» 


8 


2.7 


3.9 


1.44 


AMNH 10065 


24.2 


5 


1.3 


1.1 


0.85 


>t 




6 


1.3 


1.2 


0.92 


t> 


>f 


7 


1.6 


1.5 


0.94 


tt 


f> 


8 


1.5 


1.5 


1.00 


MCZ(H)146146 


12.8 


5 


1.0 


0.6 


0.60 


» 


» 


6 


1.0 


0.7 


0.70 


>» 


» 


7 


1.1 


0.8 


0.73 


ft 


i» 


8 


1.0 


0.9 


0.90 



iThe bottom of the posterior end of this centrum is somewhat damaged so 
that a precise measurement is impossible; the figure recorded here is an 
estimate. 



20 BREVIORA No. 436 

TABLE 5 

Measurements (in era) of the known appendicular skeletal elements of 
Sttipendemys geographicus. 

SCAPULOCORACOID (MCZ[P]4376) 

Cleft: 36.2 

lengths (as preserved) of dorsal processes of scapulae -: . , oq ^ 

lengths (as preserved, along anterior edge, start- 
ing from lateral side of glenoid fossa) of ventro- ^eft: 25.3 
medial prongs of scapulae bright: 26.9 

Cleft: 37.0 

lengths of covacoids j right: 36.9 

HUMERUS (MCZ[PJ4378) 

length (as preserved) 31.0 

estimated total length 34 

maximum width of proximal expansion (as preserved) 18.0 

maximum width of distal expansion 15.0 
dorsoventral width at middle of shaft 8.3 

anteroposterior width at middle of shaft 6,4 

combined widths of ulnar and radial condyles on ventral surface 10.1 

FEMUR (MCNC 244) 

length (as preserved) 29.5 

estimated total length 33-34 

maximum width of distal expansion 15.7 
dorsoventral width at middle of shaft 6.5 

anteroposterior width at middle of shaft 8.0 



1976 



WORLD S LARGEST TURTLE 



21 




Plate 1. The carapace of Stupendemys geographinis (MCZ[P]4376) , in 
dorsal view. Note especially the strongly curled bone at the base of the 
antero-median indentation. Midline length of this specimen is 218 cm. 
Peripheral bones in the region of the bridge on both sides, some of the more 
anterior peripherals on the right, and the lateral ends of some of the 
pleurals have been restored. 



22 



BREVIORA 



No. 436 






l_ 



cm 



50 
1 



Figure 1. Carapace of the type of Stupendemys geographicus (MCNC 
244) showing the shapes and positions of the second through seventh neural 
bones. 



1976 



WORLD S LARGEST TURTLE 



23 








cm 



50 



Figure 2. Sketch of a plastron (MCNC 245) referred to Stupendemys 
geographicus, showing the unusual position of the pectoral-abdominal scute 
sulcus. The full extent of the abdominal -femoral scute sulci cannot be 
traced. 



24 



BREVIORA 



No. 43& 







Figure 3. The seventh (bottom; MCZ[P]4376) and eighth (top; a com- 
posite based on MCNC 244 and MCZ[P]4377) cervical vertebrae of Stu- 
pendemys geographicus in left lateral (left) , anterior (center) , and posterior 
(right) views. 




Figure 4. The fifth through eighth cervical vertebrae of Podocnemis ex- 
pansa (MCZ[H]4469) in left lateral view. The arrow points toward the- 
anterior end of the neck. Compare with the lateral views of Figure 3. 



1976 



WORLD S LARGEST TURTLE 



25 





I L_ 



cm 



5 



for AMNH 13582 & MCZ(H) 4467 




scapula 



cm 10 



for MCZ(P) 4376 

Figure 5. The ventral elements of the left scapulocoracoid of Stupendemys 
geographicus (MCZ[P]4376; bottom) juxtaposed with comparable bones of 
the Recent pelomedusids Podocnemis unifilis (MCZ[H]4467; middle) and 
Pelusios castaneus (AMNH 13582; top) . The midline axis of the specimens 
to which they belong would be toward the left margin of the page. The 
arrow points anteriorly. The glenoid socket of the fossil faces forward while 
those of the Recent specimens are directed laterally. For clarity, the dorsal 
prong of the scapula and the suture between the scapula and coracoid 
have been omitted. 



26 



BREVIORA 



No. 436 





3 civT^iSiSs^P 

M i l 

Figure 6. The left humerus of Stupendemys geographicus (MCZ[P]4378) 
m dorsal (left) and ventral (right) views. 



1976 



WORLD S LARGEST TURTLE 



27 





3 CM 





Figure 7. The left humerus (top) and left femur (bottom) of Podocnemis 
expansa (MCZ[H]4469) in dorsal (left) and ventral (right) views. Compare 
with Figures 6 and 9. 



28 



BREVIORA 



No. 436 




Figure 8. The right humerus of Taphrosphys sulcatus (PU 18707) in 
ventral view, showing the prominent ridge extending from the base of the 
ulnar process to just above the radial condyle. Compare with Figure 6. 



1976 



WORLD S LARGEST TURTLE 



29 




3 CM 

I I I I 




Figure 9. The left femur of Stupendemys geographicus (MCNC 244) in 
dorsal (left) and ventral (right) views. 



30 BREvioRA No. 436 

ACKNOWLEDGMENTS 

My thanks go first to my colleagues in the field during the 
summer of 1972, Messrs. Bryan Patterson, Arnold Lewis, Daniel 
Fisher, Robert Repenning, and Michael Stanford, all of whom 
helped to collect the various specimens of Stupendemys found 
by the expedition. Without the splendid cooperation of our 
Venezuelan colleagues from the Escuela de Geologia, Universi- 
dad Central de Venezuela (especially Profesora Lourdes de 
Gamero) and the Ministerio de Minas e Hidrocarburos, our 
fossil collecting in Venezuela would have been impossible. 
Funds for our field work were provided by National Science 
Foundation grant no. GB-32489X to Professor Patterson. I 
am, in addition, grateful to the National Geographic Society 
for its support of my research on South American turtles. 
Mr. Arnold Lewis supervised the monumental task of preparing 
the specimens of Stupendemys for study and exhibition in his 
usual capable manner, and I am particularly indebted to him. 
The considerable talents of Messrs. Al Coleman and Laszlo 
Meszoly are responsible, respectively, for plate 1 and figures 
3, 4, and 6-9. For information, access to or loan of specimens 
in their care, I am grateful to: W. AufTenberg; D. Baird; 
D. Fisher; J. Ojasti; L. Price; P. Pritchard; E. Williams; and 
R. Zweifel. Finally, my special thanks go to Professor Patterson 
for critically reading several manuscript versions of this paper. 

REFERENCES CITED 

AuFFENBERG, W. 1974. Checklist of fossil land tortoises (Testudinidae) . 
Bull. Fla. State Mus., Biol. Sci., 18: 121-251. 

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