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Tag: amphicyonids

Bear dogs once roamed Texas, or, why it’s important to check that miscellany drawer

beardog

Every home has at least one — that drawer in which you place things that have no assigned place: rubber bands, soy sauce packets, take-out menus, the owner’s manual to that extinct VHS player you bought in the 1980s.

Such drawers become a crypt for things you mostly didn’t need to keep in the first place, but often there are some forgotten treasure mixed in with them.

The importance of revisiting the miscellany drawer from time to time is displayed in this story — about a researcher at the Field Museum in Chicago, new on the job, whose opening of a drawer of miscellaneous and not fully identified carnivore fossils led to the establishment of not just one new genus, but two and, in doing so, a better understanding of the evolution of dogs and other mammals.

“I had just started at the Field, and I was getting the lay of the land, exploring our collections,” Susumu Tomiya said. “In one room of type specimens, the fossils used as a standard to describe their species, I stumbled across something that looked unusual.

“There were beautiful jaws of a small carnivore, but the genus the specimen had been assigned to didn’t seem to fit some of the features on the teeth. It made me suspect that it belonged to a very different group of carnivores.”

That specimen, and a similar one Tomiya came across, had both been found 30 years ago in southwest Texas.

beardog-jawBoth had been labeled as belonging to a genus called Miacis, but Tomiya’s suspicions — based on the apparent sharpness of their teeth — turned out to be right.

The findings were revealed last week in a paper published in the journal Royal Society Open Science.

Tomiya and his coauthor used a computed tomography (CT) scanner to create 3D visualizations, and determined the specimens were those of amphicyonids, and the oldest known members of that family, which went extinct 2 million years ago.

Amphicyonids, commonly called bear dogs, are believed to be the ancestors of both bears and dogs.

“Ever since amphicyonids were given their common name, they have been overshadowed by the bear and dog families, which are more widespread, better known today, and less extinct! Our study provides a renewed sense of identity to a group that left their own mark during their 38-million-year history,” Tseng said.

Amphicyonids ranged from the size of a Chihuahua to the size of a brown bear.

They tended to get larger throughout their evolutionary history, which might have contributed to their extinction.

(At top, artist’s reconstruction of a 38 million year old amphicyonid, by Monika Jurik; lower photo, the jawbone of an amphicyonid; both provided by The Field Museum)