Sunday, May 22, 2016

[PaleoMammalogy • 2016] Protovis himalayensis • An Early Sheep from the Pliocene of Tibet, (Bovidae, Caprini), and Origin of Ice Age Mountain Sheep


Fig. 2 Map of extinct and extant species of Ovis in Eurasia and their evolutionary relationships.
Image by WANG Xiaoming   english.cas.cn

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 OvisProtovis 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.

Fig.1 Holotype of Protovis himalayensis, in frontal-lateral view (A) and dorsal view of horncores (B), and cross-sectional shapes at four intervals along left horn
Image by WANG Xiaoming  english.cas.cn

Fig. 3 Artist reconstruction of a male Zanda sheep, Protovis himalayensis, placed in a modern Zanda basement outcrop that was widely exposed during basin formation. 

Art by Julie Selan and photo background by WANG Xiaoming  english.cas.cn


Xiaoming Wang, Qiang Li and Gary T. Takeuchi. 2016. 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. Journal of Vertebrate Paleontology.   DOI: 10.1080/02724634.2016.1169190
http://zoobank.org/urn:lsid:zoobank.org:pub:F2AEE746-0A5B-4F40-89B7-8EF0C04F21FD



New Species from the Pliocene of Tibet Reveals Origin of Ice Age Mountain Sheep

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 by a few isolated records at a few Pleistocene sites in North China, eastern Siberia, and western Europe, but are so far absent from the Tibetan Plateau.

In a paper published May 4 in the Journal of Vertebrate Paleontology, paleontologists from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences, Natural History Museum of Los Angeles County and La Brea Tar Pits and Museum at Los Angeles reported a new genus and species of fossil sheep from the Pliocene of Zanda Basin in Tibet. This finding extends the fossil record for the sheep into the Pliocene of the Tibetan Plateau, suggesting 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, which is consistent with the Out-of-Tibet hypothesis regarding the origins of Ice Age megaherbivores.

New fossil materials were collected from IVPP locality ZD0712 in Guanjingtai, Zanda County, Tibetan Autonomous Region in western Himalaya during the 2006 and 2007 field seasons. The holotype specimen (IVPP V18928), forming the main basis of this new species, is a nearly complete male left and right horncores. With a total horncore upper curve length of 443 mm, it is similar in size to some extant species of Ovis.

This new extinct sheep, Protovis himalayensis, has a combination of features distinguishable from other species such as Ovis, Pseudois and Tossunnoria. Smaller than the living argali, it shares with Ovis posterolaterally arched horncores and partially developed sinuses and possesses several transitional characters leading to Ovis.

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New species from the Pliocene of Tibet reveals origin of Ice Age mountain sheep http://phy.so/382171822 via @physorg_com

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