Extinction, Climate Change, and Tropical Swamplands (65-55 Million Years Ago)

Skeleton of the crocodile Borealosuchus

A devastating mass extinction event occurred about 65 million years ago, killing the last of the dinosaurs and about 75 percent of life on Earth. Explore possible causes of the extinction and view a display of meteorites.

Learn how the Earth’s climate changed after this extinction, creating a welcoming environment for plants and animals to recover. Mammals grew in size, diversified, and evolved, signaling the end of the age of reptiles and ushering in the age of mammals – including (millions and millions of years later) humans.

A diorama and wall-size mural simulate western North Dakota as it was 60 million years ago--a tropical forested swampland.

See some of the species that flourished here:

  • A 12-foot-long crocodile Borealosuchus skeleton cast
  • A 3-foot-long salamander Piceoerpeton skeleton cast
  • An 8-foot-long skeleton of Champsosaurus (crocodile-like animal)
  • A Plesiadapis (a lemur-like mammal) skeleton cast
  • A Titanoides (a bear-size mammal) skull
  • Fossils of plants and animals that lived in the Cannonball Sea, the last sea to cover North Dakota
  • Several beautifully preserved leaf and seed fossils
  • A display of several specimens of North Dakota’s state fossil, Teredo-bored petrified wood