Loading

Documenting Climate Change: White River Group KU Natural History Museum

The fossils in this exhibit come from the White River Group. It is one of the richest sources of fossil mammals in North America and documents dramatic changes in climate and environment from 37-30 million years ago.

Eocene/Oligocene Landscape by Scientific Illustrator, Oscar Sanisidro

The fossil mammals in this exhibit are represented in the illustration above. Scroll down to learn more about these animals. See if you can find them in the landscape at the bottom of the page.

Climate Change During the Age of Mammals: From Forest to Open Plains

Warm subtropical forests covered North America during most of the Eocene. These forests teemed with diverse groups of mammals including brontotheres, entelodonts and creodonts, and were also home to early primates. Over millions of years, the climate became cooler and drier, changing the landscape to more temperate woodland and open plains.

Brontothere: an extinct relative of rhinos, tapirs and horses

Megacerops coloradensis

White River Group Map. Specimen found in Custer County, SD
Megacerops coloradensis scale illustration

Oreodont: an extinct group related to camels and pigs

Merycoidodon culbertsoni

White River Group Map. Specimen found in Niobrara County, WY
Megacerops coloradensis scale illustration

Entelodont: an extinct pig-like group most closely related to hippos and whales

Entelodon imperator

White River Group Map. Specimen found in Custer County, SD
Entelodon imperator scale illustration

Creodont: an extinct group of carnivorous mammals

Hyaenodon mustelinus

White River Group Map. Specimen found in Converse County, WY
Hyaenodon mustelinus scale illustration

A Mammal Fauna in Transition: From Browsing Beasts to Small Grass and Seed-eaters on the Open Plains

The White River Group documents the transition from warm, subtropical forests to cooler, drier environments with more extreme seasons in the Oligocene. This change led to the extinction of forest-dwelling mammals like brontotheres and primates in North America. In contrast, rabbits, rodents, horses and carnivores thrived and diversified in the more open seasonal environments of the Oligocene.

Early relative of wolves, dogs and other canids

Hesperocyon lippincottianus

White River Group Map. Specimen found in Yuma County, CO
Hesperocyon lippincottianus scale illustration

Early Horse

Mesohippus

Specimen found in North America

Mesohippus scale illustration

Early relative of deer and antelope

Leptomeryx evansi

White River Group Map. Specimen found in Logan County, CO
Leptomeryx evansi scale illustration

Early relative of deer and antelope

Hypisodus minimus

White River Group Map. Specimen found in Converse County, WY
Hypisodus minimus scale illustration

Early relative of rabbits and pikas

Palaeolagus

White River Group Map. Specimen found in Converse County, WY
Palaeolagus scale illustration

Early rodent

Eumys

White River Group Map. Specimen found in Converse County, WY
Eumys scale illustration

Can you identify the illustrations? Click the image to enlarge. Check your answers with the key.