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The Postcranial Skeleton of the Giant Permian Pelycosaur Cotylorhynchus Romeri

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The Postcranial Skeleton of the Giant Permian Pelycosaur Cotylorhynchus Romeri The Postcranial Skeleton of the Giant Permian Pelycosaur Cotylorhynchus romeri J. WlLLlS STOVALL, LLEWELLYN I. PRICE, AND ALFRED SHERWOOD ROMER Museum of Comparative Zoology, Harvard University HARVARD UNIVERSITY VOLUME 135, NO. 1 CAMBRIDGE, MASSACHUSETTS, U.S.A. SEPTEMBER 22, 1966 THE POSTCRANIAL SKELETON OF THE GIANT PERMIAN PELYCOSAUR COTYLORHYNCHUS ROMERI J. WlLLlS STOVALL, LLEWELLYN I. PRICE, AND ALFRED SHERWOOD ROMER Introductory noie. In 1937 fragmentary paper may contain, I have felt that the remains of a gigantic new pelycosaur from paper should be considered as a joint effort, the Oklahoina Permian were brought to the to give credit to Dr. Stovall for his work attention of Dr. Stovall of the University of in the collection and supervision of prep- Oklahoma. ~7hoshortly after published a aration of the material, and to Mr. Price for prelinlinary account of the animal, as Coty- his invaluable notes and drawings of the lorhynchus romeri. aided by notes and draw- Oklahoma materials. ings by Llewellyn I. Price and myself (Sto- -Alfred Shenvood Roiner vall, 1937). Subsequently, many additional specimens of this form were found: these MATERIALS n-ere prepared under Dr. Stovall's direc- tion. and studies and drawings were made Although a broad band of continental of much of the material by Mr. Price. It Pelmian beds extends across Oklahoma was planned that the material be described from the Kansas border to the Red River, in a joint paper by Stovall and Price, but relatively few vertebrates have been &s- owing to a variety of circumstances, this covered in the Lower Permian of the state was never 14 ritten. Nearly thirty years have -quite in contrast to the situation to the passed and except for a brief notice and south, in northern Texas. This relative pau- figures of the skull in the "Review of the city of finds appears to be due to the gen- Pelycosauria" (Romer and Price, 1940: erally higher rainfall and consequent better 419421). no further account of Coty- vegetative covering in Oklahoma, and to lor17ynclzu.s has appeared. hgeanwhile Dr. the more level topography of Oklahoma, in Stovall has died, and h4r. Price is now contrast to the Texas area where the pres- resident in Brasil. Adding to the need for ence of a number of limestones and heavy description is the fact that Dr. E. C. Olson sandstones makes for a more rugged to- has found additional remains of Coty- pography and the development of poten- Io~l~yi~cl~ns.and a number of related forms tially fossiliferous "breaks." have been discovered in a variety of locali- The discovery of abundant remains of a ties and horizons in Texas aild even in large new type of caseid pelycosaur, Coty- Russia (Olson. 1962: 24-47). In ths situa- lorhy~zcl~usron~eri, was in consequence a tion, it has been agreed that I should pub- major event in the history of paleontological lish a general account of the postcranial work in Oklahoma. As noted in Stovall's anatomy of Cotylorhynclzus. But although paper (193'7: 308): the first find of Coty- I alone should be held responsible for any lo1.11ynchz~smaterial was made by Dr. W. S. inaccuracies or misinteil~retationsthat this Strain (then a graduate assistant at the Bull. Mus. CcImp. Zool., 135(1): 1-30, September, 1966 1 2 Bulletin Museum of Con~parativeZoology, Vol. 135, No. 1 University of Oklahoma). The site lay in the Hennessey shales, 4% miles west of Kavina, Logan County. The type specimen Specimen No. Humerus Radius Femur Tibia consisted of an incomplete skull and jaw. a 4-0-6 4-0-2 (1249) front foot, and interclavicle. Shortly after. 4-0-4 a nearly complete postcranial skeleton was CNHM 272 found at about the same horizon in the AhslNH 7517 Hennessey Formation. but close to the city 1250 (?) 4-0-16 of Norman and hence some 50 miles or so USNM from the region of the first discovery. and MCZ 3416 during the years 1937-1939 a very con- 4-0-13 siderable number of further Cotylorhyncht~s 4-0-3 specimens were collected in the Hennessey shales of the Nom~andistrict and prepared by laborers under Works Progress Admini- man area can be assigned to a single species stration funds. Most of this material is now as far as morphological characters are con- in the Stovall Museum at Norman. but cernedS1 There is however, considerable specimens were also obtained for the mu- variation in size. In reptiles generally. early seums in Chicago, New York. TVashington. growth is rapid. followed by a slower if and Cambridge. Preparation of the mate- steady growth; the natural result is that the rials at Norman was carried out under the greater part of specimens recovered in the general direction of Dr. Stovall. and notes case of fossil forms should represent rela- and figures on much of the material were tively young mature animals. with a small made by Mr. Price. In the preparation of percentage of overly large specimens repre- the present description. Romer has seen senting individuals which were exception- all this material and has utilized Price's ally long-lived and consequently exception- notes and figures in addition to his own ob- ally large: and a small percentage of young servations. A word of caution must be and immature individuals. The present ma- gi\ en, however. Although preparation was terials tend to show a rather greater size carried out under Dr. Stovall's direction. range than is common. As a rough index to it is not improbable that. with a consider- size, I list the length (in mm) of major limb able number of workers and with a number elements in a number of the better speci- of specimens undergoing simultaneous prep- mens ( Table 1) . aration, a certain amount of inaccuracy These specimens are deposited in the may have occurred in the restoration and following institutions: Chicago Natural association of materials. Further. in the History h4useum ( CKHM ) : American Mu- time that has since elapsed, some of the seum of Natural History ( Ahlh'H) ; United specimens have been moved several times States National hluseum (USNM): Museum for storage and re-cataloging and further of Comparative Zoology, Harvard ( MCZ ) . chances of error have crept in. Other specimens (numbered) are in the The reptilian remains from the Hennessey University of Oklahoma collection. shales of the Norman region appear. curi- As can be seen from this table. the first ously, to pertain almost entirely to Coty- five specimens listed appear to be of rela- lorhynchus. with very few remains of other tively uniform large size. Below this there reptiles and amphibians-a situation in is a sharp drop to three specimens which are 20 per cent or so smaller than the first strong:u contrast to the usual mixed assem- blages generally present in typical Texas Dr. Olson infornls rile that there is a possible redbeds deposits' As far as be seen, specific difference between the Norman material the Cotylorlzynchus materials from the Nor- and the type from Navina. COTYLORHYNCHUSSKEI~ETOK Stovall, Price, and Romer 3 group but appear to be essentially mature; of structures given here are based on a below. with the MCZ specimen as a tran- synthesis of a number of specimens. Wher- sition there is a drop to small and seem- ever possible the illustrations are based on ingly immature specimens such as 4-0-3. specific examples. although frequently with Possibly there is a specific difference be- the addition from other individuals of de- tween the first and second groups. Equally tails missing or obscured in the specimen possible. however the contrast is a sexual primarily utilized. one: in Dimetrodon limbattu. for example. It became apparent. even from the ma- there is a seemingly clear-cut size difference terial described in Stovall's preliminary of 10 per cent between the sexes (Romer paper, that Cotylo~hyiichuswas a @ant rel- and Price, 1940: 341342). ative of Casea. a small Clear Fork Texas In typical Texas redbeds localities. fossil pelycosaur described by Williston ( Willis- reptile remains are most conlmonly found in disarticulated con&tion. and when found ton. 1910: 590-592: 1911: 111-131, etc.; articulated appear to have undergone de- Romer and Price. 1940: 412419). Despite position in a variety of poses. One gets the cranial differences, Casea and a number of impression that this is the result of stream other Texas pelycosaurs show such a large action, and that many of the "bone pockets" number of diagnostic postcranial similari- represent back eddies in streams in which ties to Eduphosaurus that Romer (Romer cadavers brought donnstream tended to and Price, 1940: 21. 366-378) felt justified collect (and decompose). But in the Hen- in including these forms with Edaphosaurus nessey shales of the Norman region. many in a common suborder Edaphosauria. As in of the specimens show clearly that the Casea, the Cotylorhynclius postcranial skele- Cotylorhyizchus individuals were generally ton agrees in almost every particular with buried in articulated and undisturbed the characteristics assigned to the Edapho- fashion, right side up, with the limbs spread saulia as a whole. In consequence. in the outward at the sides. This strongly suggests description which follows. comparisons are. that we are here dealing with entombment in general, with Cnsea or other edapho- of quite another sort. South African Per- saurian types. mian pareiasaurs, equally large and clumsy herbivores, are typically preserved in simi- lar fashion (Watson. 1913). There are two VERTEBRAL COLUMN possible interpretations. Watson, in the The general characteristics of the Coty- case of the pareiasaurs. implies death from lorlzynclzus vertebral column are almost ex- starvation, and suggests a covering of the actly those cited in the "Review of the cadavers in situ by loess-like materials.
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