Tuesday 9 July 2019

OLIGOCENE FOSSIL BEAVER

This may be the cutest fossil skull you'll see all day. This is Microtheriomys brevirhinus, an adorable teeny, 19 mm, fossil beaver skull from the John Day Formation in Oregon. Awe, right?

Paleontologists Dr William Korth of Rochester Institute of Vertebrate Paleontology and Dr Joshua Samuels of John Day Fossil Beds National Monument were chuffed to find a treasure trove of new fossil species during field work this past year building on the knowledge from previous finds. They have described four new genera and ten new species of prehistoric rodents that lived in what is now Oregon during the Oligocene -- 30- 22 million years ago.

The newly-discovered genera include this wee fellow, the early beaver, Microtheriomys brevirhinus, a dwarf tree squirrel, Miosciurus covensis, a primitive pocket mouse, Bursagnathus aterosseusm the birch mouse Plesiosminthus fremdi, an early relative of beavers, Allotypomys pictus along with bits and pieces of Proapeomys condoni; Apeomys whistleri; Neoadjidaumo arctozophus, Proheteromys latidens & Trogomys oregonensis.

Of these ten new species, four represent completely new genera: Allotypomys, Microtheriomys, Proapeomys, and Bursagnathus. It's a bit like winning the paleo lottery.

“This study fills some substantial gaps in our knowledge of past faunas, specifically smaller mammals,” said Dr Samuels, who is a co-author of the paper published in the Annals of Carnegie Museum. “Some of the new species are really interesting in their own right, and will ultimately help improve our understanding of the evolution of beavers and pocket mice.”