From unknown to beardog: Findings rescue fossils from 'trashbin' genus

Date: October 12, 2016

Source: University at Buffalo

Large, ferocious-looking animals called beardogs -- neither bears nor dogs -- roamed the northern hemisphere between about 40 and 5 million years ago.

But because so little data on their earliest members are available, their evolutionary relationships or phylogeny -- and their place on the tree of life -- has remained unclear.

A new study published Oct. 11, 2016 in Royal Society Open Science and based on improved phylogenetic analysis and advanced computed tomography (CT) scanning has changed that. The research identifies two fossils previously thought to be generic carnivorans (a large, diverse order of mammals) as some of the earliest known members of the beardog family. These fossils are from animals estimated to be no larger than about five pounds, roughly the size of a Chihuahua and much smaller than formidable descendants that would later evolve.

The work reveals that while evidence of beardogs has been found throughout the Northern Hemisphere, they may have originated or initially diversified in parts of what is now the southwestern U.S.

"Our research pinpoints the southwestern US as a key region in understanding the diversification and proliferation of this once successful group of predators prior to their extinction millions of years ago," said study coauthor Jack Tseng, PhD, assistant professor in the Department of Pathology and Anatomical Sciences in the Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo.

The evolutionary roots of beardogs

First described back in 1986, fossils found in Texas of animals believed to be less than 5 pounds were originally assigned to the genus Miacis, a kind of "miscellaneous" category for early carnivores, based primarily on external features.

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