6 October 2009. Edmonton, AB Canada
The 2009 expedition led by Dr. Qiang Li of the IVPP to the Zhada Basin in western Tibet yielded a new discovery very dear to my heart...
On the third day after the small team of seven arrived in the basin, they were prospecting along the badlands of the Zhada wash when team member Dr. Min Zhao came to a pile of scattered bones and teeth.
They were fragments of a fossil hyena. Unfortunately, only bits of the cranium were preserved; and although the dentary bones are more complete, the teeth are very busted.
This exciting discovery awaits my next visit to Beijing. From the loss of p1, relatively slender premolars, very reduced P4 protocone and m1 metacone, and a three-cusped m1 talonid, I am guessing this beast belongs somewhere in the lineage of the hyena Chasmaporthetes.
Even though we still don't have a very good idea what the exact vertical distribution of mammal fossils is in the basin (or how much time the entire sequence encompasses), we are somewhere in the Plio-Pleistocene as the small mammals (mostly pikas) show.
Interestingly, Chasmaporthetes is the only hyena to have made it to North America, the rest of the family confined to the Old World from Africa to East Asia. Chasmaporthetes and their relatives (Hyaenictis and Lycyaena) are found in East Asia in eastern China and the Siwaliks of India, but they have never been found on the Tibetan Plateau.
Was the Tibetan Plateau such a barrier that large mammals that were widespread throughout the late Cenozoic of Eurasia were not present on that raised land in the middle of Asia? Some endemic bovids (see previous post) seem to support this point, but others like this new hyena challenge the idea of an isolated plateau fauna (or rather, refine the timing and extent of various isolation events). The story is probably complicated as current fossils show, and will take much additional work by future expeditions to tease out.
For now, I am content with a new hyena occurrence that we can point to and say: see, it was supposed to be there, we just didn't look hard enough...
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