CU Boulder paleontologists have discovered three new species of fossil mammals that were the ancestors of today’s hoofed animals, such as cattle, horses, deer and moose, but much smaller. Analysis shows that these species lived a few hundred thousand years after the mass extinction event.
Paleontologists discovered these species at the site of an ancient riverbed in southern Wyoming. This discovery shows what western North America looked like after the extinction of the dinosaurs.
To fill in the gaps, scientists dug into a collection of condylarth fossils, mostly pieces of jawbones and teeth, which they collected from Wyoming’s Great Divide Basin in the 2000s. Today, the site is a patch of dry, brushy land not far from the town of Rawlins.
Scientists have examined the fossilized teeth and jaws of mammals. They discovered that the species belongs to the category of primitive ungulates informally called “Condylarths”. The first Condylarth is thought to be the size of a domestic cat. These species live for the first approximately 328,000 years after the dinosaurs died out, a period known as the early Puercan age.
Condylarthra were the most abundant group of mammals in North America. Based on the shape of their teeth, the three new species may have been omnivores that ate both meat and plants.
Scientists have named the owner of these swollen molars Beornus honeyi – a nod to Beorn from JRR Tolkein’s The Hobbit, a character who is sometimes “a big strong man” and sometimes “a huge black bear”.
Scientists also discovered two other new species from the same region: Miniconus Jeannine and Conacodon Hettinger. These three species belong to the Periptychidae family.
Jaelyn Eberle, Curator of Fossil Vertebrates at the CU Museum of Natural History and Professor of Geological Sciences, said: “Many paleontologists have assumed that in early Puercan much of the West was home to the same handful of common mammal species, all the size of rodents. But new fossil discoveries suggest that mammals may have -began to spread across the region, developing larger and more specialized body types, earlier than researchers suspected.
“Looking at the first geological minutes of the Puercan is essential to understanding the evolution of mammals over the millions of years that followed, including the origin of the current orders of mammals.”
- Madelaine R. Atteberry and Jaelyn J. Eberle. New Paleocene (Puercan) periptychid “condylarths” from the Great Divide Basin, Wyoming, USA. DOI: 10.1080/14772019.2021.1924301