AMERICAN MUSEUM Novitates PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET NEW YORK, N.Y. 10024 U.S.A. NUMBER 2688 OCTOBER 30, 1979 EUGENE S. GAFFNEY AND MALCOLM C. MC KENNA A Late Permian Captorhinid from Rhodesia IITVWW"Wkq..-, if AMERICAN MUSEUM Novitates PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, N.Y. 10024 Number 2688, pp. 1-15, figs. 1-6, tables 1, 2 October 30, 1979 A Late Permian Captorhinid from Rhodesia EUGENE S. GAFFNEY' AND MALCOLM C. MC KENNA2 ABSTRACT Two partial skulls from the late Permian torhinidae is a monophyletic group (possibly Madumabisa Mudstone in the Middle Zambezi Basin including turtles) with these derived characters: of Rhodesia belong to the captorhinid genus Pro- downturned premaxilla, ectopterygoid and tabular tocaptorhinus. Heretofore, Protocaptorhinus has absent, medial process of jugal. Protocaptorhinus been known only from the Early Permian of Texas, differs from Romeria in having a shallow median whereas Africa has yielded only one other cap- parietal embayment and differs from remaining cap- torhinid, Moradisaurus, from Niger. The Cap- torhinids in lacking a retroarticular process. INTRODUCTION In May 1976, Mr. Brian Hosking and the in Kuhn (1969), but the papers that are the junior author made a small collection of therap- most pertinent to this study are Clark and Car- sid and captorhinid skulls from a late Permian roll (1973) and Heaton (1979). locality in Rhodesia. The two captorhinid spec- The junior author provided the geologic and imens are of particular interest because they locality information (as well as the specimens), provide the second record of this group from and the senior author is alone responsible for Africa. The captorhinid skulls have been identi- the morphology and discussion sections. fied as Protocaptorhinus, a form previously known only from the Early Permian of North ACKNOWLEDGMENTS America. The Captorhinidae is usually placed We are particularly indebted to Dr. Robert in the Captorhinomorpha, an avowedly para- Carroll, McGill University, Montreal, and Drs. phyletic group that is generally considered to Malcolm Heaton and Robert Reisz, Erindale contain the ancestors of later amniotes. This University, Toronto, for sharing their speci- situation has prompted a phylogenetic study of mens and unpublished data, and for examining the Captorhinidae using shared derived char- our material and providing us with some very acters (see Gaffney, 1979, for a discussion of useful ideas. Dr. Heaton gave us free access to the methodology used here). his thesis on Eocaptorhinus which, at that time, Previous work on captorhinids and cap- was still unpublished. The very difficult prep- torhinomorphs in general has been summarized aration of the specimens was accomplished by 'Associate Curator, Department of Vertebrate Paleontology, American Museum of Natural History. 2Frick Curator, Department of Vertebrate Paleontology, American Museum of Natural History. Copyright (©) American Museum of Natural History 1979 ISSN 0003-0082 / Price $1.30 2 AMERICAN MUSEUM NOVITATES NO. 2688 Mr. Gil Stucker using an air abrasive machine. Rhodesia. Fossils occur in sideritic concretions Mr. Chester Tarka and Ms. Lorraine Meeker forming a lag concentrate. produced the illustrations. HolUZON: Middle Madumabisa Mudstones, We also thank Professor G. Bond and Mr. K5d of Bond (1973); late Permian (Dzhulfian) in Brian Hosking of the Geology Department, age. The captorhinids were found associated University of Rhodesia, for their hospitality and with therapsids, most of which are endothio- logistic support of the junior author, both in donts similar to Emydops (C. B. Cox, personal Salisbury and in the field. Dr. Raath, formerly commun.). Director of Museums and Monuments of Rho- COLLECTORS: Malcolm C. McKenna and desia, now at the Bernard Price Institute, Brian Hosking, May 1976. Johannesburg, generously arranged for permis- sion to collect and for the loan of specimens DESCRIPTION for study. Dr. C. B. Cox, University of London, King's College, identified the associ- Among the captorhinid taxa used for com- ated anomodont material. parisons here, Captorhinus and Eocaptorhinus are by far the best known, being represented by ABBREVIATIONS a number of well-preserved skulls. Price (1935) INSTITUTIONS and Fox and Bowman (1966) have produced OU, University of Oklahoma descriptions of Captorhinus, and Heaton (1979) QG, National Museums of Rhodesia has described Eocaptorhinus in even greater ANATOMICAL detail. Considering that the two taxa differ only ang, angular pfr, prefrontal in the number of tooth rows (providing that one art, articular pm, premaxilla accepts the hypothesis that they are different at bo, basioccipital po, postorbital all), this skull type is as well known as any den, dentary ps, parasphenoid Recent form. Romeria and Protocaptorhinus, fr, frontal pt, pterygoid however, are known from three and two skulls, ju, jugal qj, quadratojugal respectively, all of which lack significant por- la, lacrimal qu, quadrate mx, maxilla sm, septomaxilla tions of the palate (Clark and Carroll, 1973). na, nasal sq, squamosal The currently known material of Romeria and pa, parietal st, supratemporal Protocaptorhinus and the excellent specimens pal, palatine vo, vomer of Captorhinus and Eocaptorhinus were avail- pf, postfrontal able for comparison with the Rhodesian Pro- tocaptorhinus during the course of this study. SYSTEMATICS In many cases comparisons had to be restricted to Captorhinus and Eocaptorhinus because of FAMILY CAPTORHINIDAE the poor preservation of Romeria and Protocap- Protocaptorhinus Clark and Carroll, 1973 torhinus specimens. In the following descrip- tion, Protocaptorhinus always refers to the Protocaptorhinus, sp. North American material, the Rhodesian skulls SPECIMENS: QG 1105, anterior portion of are not identified as Protocaptorhinus until the skull; QG 1106, posterior portion of skull (see Discussion section. figs. 1-3). LOCALITY: Small patch of badlands lying at SKULL the base of a large hill just south of the con- fluence of the Sengwa and Lutope rivers, PREMAXILLA: The premaxilla is best seen on 18°07' S. latitude, 28°12' E. longitude'; Gokwe the right side of QG 1105 where only a portion Tribal Trust Area, Middle Zambezi Basin, of the internarial region is badly damaged. The preserved areas agree closely with Captorhinus 'UTM grid reference PL283009 on 1:50,000 series of and Eocaptorhinus as described by Fox and Rhodesia, sheet 1828A. Bowman (1966) and Heaton (1979). Although 1979 GAFFNEY AND MC KENNA: CAPTORHINID 3 all the premaxillary teeth are damaged to some SEPTOMAXILLA: Although one was presum- extent, it does seem clear that each bone has ably present, the septomaxilla is not visible. four teeth. Protocaptorhinus, Captorhinus, and LACRIMAL: The lacrimal is preserved best on Eocaptorhinus have four or five premaxillary the right side of QG 1105 and extends from the teeth and a distinct size gradation in these teeth anterior edge of the orbit to the posterior edge with the anteriormost being longest and widest of the nares. It compares closely with Pro- and the posteriormost being shortest and small- tocaptorhinus, Captorhinus, and Eocap- est. The Rhodesian specimen is consistent with torhinus. these characters but the anteriormost tooth does NASAL: The limits and dorsal surface of the not seem to be relatively as large as that seen right nasal are clearly preserved in QG 1105 in the North American taxa. although the area bordering the nares is some- MAXILLA: Both maxillae are preserved in what damaged. The left nasal is broken and QG 1105, but the left maxilla is somewhat crushed but agrees in morphology with the crushed. The external limits and shape of the right. The only distinction between the nasal of maxilla agree with that seen in Protocap- the Rhodesian skull and Captorhinus is the torhinus, Captorhinus, and Eocaptorhinus. The slightly more extensive prefrontal contact and anterior limit of the maxilla forms part of the less extensive lacrimal contact in the former. narial margin, there is a mid-length dorsal PREFRONTAL: The prefrontal in QG 1105 is swelling, and a posterior jugal contact; all as in badly damaged on the left side, but complete the New World forms. The mid-length swelling on the right. It forms the border of the orbit coincides with the position of the largest max- anterodorsally and extends forward to separate illary teeth, some of which may become dis- the nasal and lacrimal for much of their tinctly larger than the other maxillary teeth. lengths. It agrees in detail with Protocap- The Rhodesian form, however, has maxillary torhinus, Captorhinus, and Eocaptorhinus. teeth that are somewhat more similar to each FRONTAL: The frontal is best seen in QG other in size and conspicuously enlarged ca- 1105 but fragments of it as well as the fronto- niniform teeth are absent. Bolt and De Mar parietal suture are preserved in QG 1106. The (1975) noted some variation in this feature in frontal agrees closely with Protocaptorhinus, Captorhinus. Captorhinus, and Eocaptorhinus. The lower jaws have not been removed from PARIETAL: QG 1106 has a complete right the skulls of the Rhodesian specimens but it is parietal and portions of the left preserved but possible to determine that a single row of teeth the posteromedial surface is damaged making is present as in Protocaptorhinus and Eocap- the midline parietal suture and the pineal fora- torhinus. men impossible to determine. The parietal in The number of maxillary teeth is in doubt the Rhodesian form differs slightly from Pro- because of the presence of the lower jaws, but tocaptorhinus, Captorhinus, Eocaptorhinus, on the right side 19 maxillary teeth are visible, and romeriids in apparently having a medial whereas the damaged left side shows evidence constriction about midway along its length. of a minimum of 12 teeth. Heaton (1979) re- Also, as restored here, the proportions of the ported 17 to 22 teeth in Eocaptorhinus, and parietal are somewhat closer to those seen in Clark and Carroll (1973) stated that Protocap- Romeria (Clark and Carroll, 1973) in that the torhinus had 18 to 22.