PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024 Number 3483, 57 pp., 17 ®gures, 8 tables July 25, 2005 Amphicticeps and Amphicynodon (Arctoidea, Carnivora) from Hsanda Gol Formation, Central Mongolia and Phylogeny of Basal Arctoids with Comments on Zoogeography XIAOMING WANG,1 MALCOLM C. McKENNA,2 AND DEMBERELYIN DASHZEVEG3 ABSTRACT Amphicticeps shackelfordi and Amphicynodon teilhardi are two small carnivorans from the early Oligocene Hsanda Gol Formation of central Mongolia, and as basal arctoids (infraorder Arctoidea) in Asia, feature unique combinations of morphologies that offer insights into early diversi®cation and zoogeography of the arctoids. Lack of adequate study of Amphicticeps and incomplete knowledge about Amphicynodon, however, prevented them from being ®gured in the discussions of arctoid relationships. New associated dental and cranial materials collected during recent expeditions in the 1990s substantially enrich our knowledge of the two genera and their stratigraphic positions, and serve as an impetus for a study of their phylogenetic relationships in the broad perspective of basal Arctoidea. Hsanda Gol arctoids are represented by six small- to medium-sized species: Amphicticeps shackelfordi Matthew and Granger 1924, A. dorog, n.sp., A. makhchinus, n.sp., Amphicynodon teilhardi Matthew and Granger 1924,? Cephalogale sp., and Pyctis inamatus Babbitt, 1999. The three species of Amphicticeps apparently form an endemic clade con®ned to central Asia, whose zoogeographic origin is currently unknown. Amphicynodon has a much higher diversity in Europe than in Asia, and phylogenetically the Asian A. teilhardi seems to be nested within 1 Division of Paleontology, American Museum of Natural History; Department of Vertebrate Paleontology, Natural History Museum of Los Angeles County, 900 Exposition Blvd., Los Angeles, California 90007; Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences ([email protected]). 2 Division of Paleontology, American Museum of Natural History ([email protected]). 3 Geological Institute, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia. Copyright q American Museum of Natural History 2005 ISSN 0003-0082 2 AMERICAN MUSEUM NOVITATES NO. 3483 the European congeneric species, indicating an eastward dispersal for this group, linking the European ``Grande Coupure'' and the Asian ``Mongolian Reconstruction'' events. To avoid excessive homoplasies in crown groups, we attempted a phylogenetic reconstruc- tion based mostly on stem arctoids. Twenty genera of primitive arctoids occupying basal positions of nearly all major clades are selected for the analysis. The resulting tree, based on 39 characters, approximates the initial divergence of the arctoids. The traditionally dichoto- mous Arctoidea, formed by sister clades Ursida and Mustelida, is recovered in our analysis. Mustelida is also largely dichotomous with mustelid-like forms on one side and procyonid- like forms on the other. Despite its rather hypercarnivorous dentition, Amphicticeps is found on the Ursida side of the arctoids, although support for such a topology is relatively weak. Amphicynodon is a stem taxon of the Ursida and is a sister to an ursid±pinniped clade. INTRODUCTION ticeps shackelfordi found by the Mongolian Academy of Sciences and the American Mu- Among the intriguing discoveries made seum of Natural History joint expeditions during the Central Asiatic Expeditions by the (MAE) during the 1994 ®eld season. The American Museum of Natural History in the new MAE materials collected throughout the 1920s were several small carnivorans found 1990s complement in important ways the in the rich deposits of Shand Gol (preferred original holotype skull by ®lling in gaps in spelling over ``Hsanda Gol'' of most previ- our knowledge of the upper and lower teeth ous literature) and Tatal Gol in the Mongo- missing in the holotype, furnish additional lian People's Republic. The initial discovery materials that indicate the existence of two of fossiliferous localities near Shand Gol (®g. more species, and help to resolve some long- 1) in 1922 led to a number of preliminary standing problems that have plagued pale- reports about a fauna that was almost entirely ontologists for many years. new to science (see Mellett, 1968, for a sum- Also among the newly collected materials mary). Amphicticeps shackelfordi Matthew are important additions to Amphicynodon teil- and Granger 1924, a small badger-sized car- hardi Matthew and Granger 1924, another nivoran, was brie¯y reported as such and be- basal arctoid that has a phylogenetic af®nity came part of a diverse Shand Gol ``fauna'' with some congeneric species from European that serves as a regional standard in the mid- early Oligocene ®ssure ®lls in the Quercy re- Tertiary of continental east Asia (Russell and gion of France. A. teilhardi was originally Zhai, 1987, and references within). based on a lower jaw fragment with m1±2, At the time of its formal announcement, and our new materials combine to include the holotype of Amphicticeps shackelfordi much of the skull and lower jaw. With such was the only specimen ®gured and brie¯y improved knowledge about the anatomy of described, and was represented by a nearly Amphicticeps and Amphicynodon, along with complete skull (Matthew and Granger, 1924). better documentation of the locality and strati- It stood out as one of the best specimens graphic data by the MAE ®eld parties, a sub- among half a dozen small carnivorans ini- stantial contribution is now possible to resolve tially reported from the Shand Gol and Tatal some long-standing systematic issues. Gol localities. Although several mandibles of Matthew and Granger (1924: 4) consid- Amphicticeps-sized individuals were collect- ered Amphicticeps so out of place in the then ed during the 1922 ®eld season (additional existing understanding of primitive carnivor- materials were also collected in 1925), Mat- ans that they originally regarded it as ``a thew and Granger did not list the isolated jaw highly progressive miacid'' rather than be- fragments, mentioning only the morphology longing to any existing family of carnivor- of the lower carnassials, presumably partly ans. Its puzzling array of mixed dental and because of a lack of a secure association of basicranial morphology seems to suggest to these mandibles with the holotype skull. recent authors (Schmidt-Kittler, 1981; Wol- This lack of association is now remedied, san, 1993; Hunt, 1996b; Wang and Qiu, more than half a century later, by naturally 2003a) a relationship of either musteloids or associated upper and lower jaws of Amphic- ursoids, two major clades of carnivorans that 2005 WANG ET AL.: CARNIVORANS FROM CENTRAL MONGOLIA 3 Fig. 1. Map of early Oligocene localities (solid circles) of basal arctoids in Mongolian People's Republic and People's Republic of China. Map locations of fossil localities are based on Russell and Zhai (1987). Amphicticeps and Amphicynodon were reported from the Khatan-Khayrkhan locality in the Altai region of western Mongolia (Russell and Zhai, 1987: 324). However, no description of the materials was given and their occurrence in this locality needs to be con®rmed. include all living families of Arctoidea (Ur- that features key anatomical innovations in sidae, Procyonidae, Mustelidae, Ailuridae, various families of the Arctoidea (e.g., Hunt, plus the Phocoidea [5 Pinnipedia] clade). 1974, 1977; Schmidt-Kittler, 1981; Cirot and With its occurrence in the early Oligocene, a Bonis, 1993; Wolsan, 1993; Wang, 1997), is critical period of time when some European still not available. With the new materials basal arctoids began to make their ®rst ap- and revised stratigraphic framework in hand, pearance, Amphicticeps seems to have fallen the time has come to address the various is- somewhere in the initial diversi®cation of the sues outlined above. We aim to accomplish arctoids and is thus relevant in discussions of the following three objectives in this contri- higher level relationships of the Arctoidea. bution: (1) to restudy the holotypes and to However, despite an exceptionally pre- describe new materials of Amphicticeps served holotype skull, Amphicticeps has not shackelfordi and Amphicynodon teilhardi; received more than a cursory mention or a (2) to place on record two new species of few speculative remarks. A detailed descrip- Amphicticeps from the Hsanda Gol Forma- tion of its basicranial morphology, a region tion, as well as more fragmentary materials 4 AMERICAN MUSEUM NOVITATES NO. 3483 of uncertain taxonomy; and (3) to conduct a Although we did not have full access to the phylogenetic analysis of the arctoids from PIN materials, casts of key specimens are Hsanda Gol Formation in relation to major available to us. The Polish±Mongolian Pa- clades of Arctoidea. leontological Expeditions in the 1960s also amassed a collection in Warsaw. Carnivores INSTITUTIONAL ABBREVIATIONS from the ZPAL collection were described by AMNH Department of Vertebrate Paleontol- Lange-Badre and Dashzeveg (1989: 141), ogy, American Museum of Natural and only a few jaw fragments were relevant History, New York in the present study. New materials collected BSP Bayerische Staatssammlung fuÈr Pa- by the Mongolian Academy of Sciences and laÈontologie und historische Geologie, the American Museum of Natural History Munich joint expeditions (MAE) add substantially to F:AM Frick Collection, Department of Ver- various anatomic components to be described tebrate