Research NewsPaleontology

Mammal Diversity Takes a 20-Million-Year Leap Backwards

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Science  24 May 1996:
Vol. 272, Issue 5265, pp. 1102
DOI: 10.1126/science.272.5265.1102

Summary

Elephants would seem hard animals to miss, but tracking them back in time hasn't been easy. Paleontologists have followed the fossil trail of elephants and their kin—the ungulates, which include whales and deer and are one of the largest orders of mammals—back to the Cretaceous-Tertiary (K-T) boundary, when the dinosaurs went extinct 65 million years ago. There researchers ran out of fossils. But on ( page 1150) of this issue, researchers report that some fossil teeth and jaws—recovered over the past decade from a windswept desert in the southwestern former Soviet Union by a now-deceased Russian paleontologist—look enough like ungulate teeth to push their ancestry back another 20 million years. And because these 85-million-year-old “zhelestids,” as the rat-sized ungulate forebears are called, were found in Asia, it opens up the possibility that ungulates first appeared there.