Chadron State College
Chadron State College

Fossil Mammals

Mammal fossils are very common at Toadstool Park. Entombed in the 30 million year old mud and siltstone are ancient camels, pigs, rhinos, deer, rabbits, pig-like creatures, predatory cats, and many others.

Rhinos once roamed the grasslands and river bottoms in this area. Move your cursor over this rhino jaw to watch it emerge from the mudstone host rock.
Carnivores called beardogs (Daphoenus shown here) hunted and scavenged across the plains. These creatures have been found nearby at Agate Fossil Beds National Monument, preserved in their burrows.
Pig-like oreodonts are the most abundant mammal fossils found in the Toadstool sediments. These widespread omnivores died out in the late Miocene, about 10 million years ago.
An oreodont jaw in the field or "in situ."