Out of Tibet: an early sheep from the Pliocene of Tibet, Protovis himalayensis, genus and species nov. (Bovidae, Caprini), and origin of Ice Age mountain sheep

ABSTRACT

Modern wild sheep, Ovis, is widespread in the mountain ranges of the Caucasus through Himalaya, Tibetan Plateau, Tianshan-Altai, eastern Siberia, and the Rocky Mountains in North America. In Eurasia, fossil sheep are known at a few Pleistocene sites in North China, eastern Siberia, and western Europe, but are so far absent from the Tibetan Plateau. We describe an extinct sheep, Protovis himalayensis, gen. et sp. nov., from the Pliocene of the Zanda Basin in western Himalaya. Smaller than the living argali, this new form shares with Ovis posterolaterally arched horncores and partially developed sinuses and possesses several transitional characters leading to Ovis. Protovis likely subsisted on C₃ plants, which are the dominant vegetation in the Zanda area during the Pliocene. With the discovery of this new genus and species, we extend the fossil record for the sheep clade into the Pliocene of the Tibetan Plateau, consistent with our previous out-of-Tibet hypothesis. Ancestral sheep in the Pliocene were presumed adapted to high altitude and cold environments, and during the Ice Age, sheep became anatomically modern and dispersed outside of the Tibetan Plateau. Both this new fossil datum and the existing molecular phylogeny suggest that the Tibetan Plateau, possibly including Tianshan-Altai, represents the ancestral home range(s) of mountain sheep and that these basal stocks were the ultimate source of all extant species. Most sheep species survived along their Pleistocene route of dispersal, offering a highly consistent pattern of zoogeography.

http://zoobank.org/urn:lsid:zoobank.org:pub:F2AEE746-0A5B-4F40-89B7-8EF0C04F21FD

SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

Citation for this article: Wang, X., Q. Li, and G. T. Takeuchi. 2016. Out of Tibet: an early sheep from the Pliocene of Tibet, Protovis himalayensis, gen. et sp. nov. (Bovidae, Caprini), and origin of Ice Age mountain sheep. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1169190.

ACKNOWLEDGMENTS

Materials described in this study were collected during the 2006 and 2007 field seasons, and we are indebted to the dedication by field participants and drivers that made our trip possible: Z. J. Tseng, Y. Wang, F.-q. Shi, W.-q. Feng, R. Laba, B. Sang, and L. Jie. We are indebted to J.-s. Dong, who provided numerous assistances in obtaining field permits. Y. Kimura provided assistance in Japanese literatures. We thank H.-w. Tong and Z.-j. Xu for permission to photograph living bharal specimens that they borrowed from the NIPB. J. Dines of Natural History Museum of Los Angeles County helped in loaning the Rupicapra specimen. We thank W.-d. Zhang of IVPP for assistance in X-ray photography. We are indebted to F. Bibi, who provided his supermatrix for a phylogenetic analysis as well as technical help in running MrBayes. We are grateful to two anonymous reviewers for criticism and suggestions that greatly improved the clarity of this paper. Financial support is provided by Strategic Priority Research Program of the Chinese Academy of Science (XDB03020104), Major Basic Research Projects of Ministry of Science and Technology of China (973 Program, No. 2012CB21904), CAS/SAFEA International Partnership Program for Creative Research Teams, Chinese National Natural Science Foundation (Nos. 41430102 and 40702004, and 41472002 to Q.L.), Chinese Academy of Science Outstanding Overseas Scholar Fund (KL205208), National Science Foundation (U.S.A.) (EAR-0446699, 0716507, 0958704, and 1227212 to X.W.), and National Geographic Society (nos. 6004–97 and 6771–00 to X.W., W22-08 to Q.L.).