55-million-year-old fossil sheds light on bizarre extinct mammal

WASHINGTON - University of Florida researchers, who found a well-preserved 55-million-year-old North American mammal, have discovered that it shares a common ancestor with rodents and primates, including humans.

High resolution CT scans of the extinct mammal, Labidolemur kayi, showed that it is related to rodents, rabbits, flying lemurs, tree shrews and primates.

“The specimens are among the only skulls of apatemyids known that aren’t squashed completely flat,” said Jonathan Bloch at the Florida Museum of Natural History on the UF campus.

With can opener-shaped upper front teeth and two unusually long fingers, apatemyids, to which L. kayi belongs, have been compared to a variety of animals, from opossums to woodpeckers.

“There are only a few examples in the history of mammals where you get such an incredibly odd ecological adaptation,” Bloch said.

Like a woodpecker’s method of feeding, L. kayi used percussive foraging, or tapping on trees, to locate insects. It stood less than a foot tall, was capable of jumping between trees and looked like a squirrel with a couple of really long fingers, similar to the aye-aye, a lemur native to Madagascar, Bloch said.

“It is now clear that any assessment of the origins of primates in the future will have to include apatemyids,” said John Wible, curator of mammals at the Carnegie Museum of Natural History.

“Apatemyids are not some freakish dead-end, but significant members of our own history.”

The study appeared in the Oct. 11 online edition of the Zoological Journal of the Linnean Society. (ANI)