BOULDER, Colo. — Paleontologists recently discovered a rare mammal fossil in western Colorado. It's a genus of mammal that lived between 70 million and 75 million years ago and has never been ...

An artist's illustration shows Deinosuchus riograndensis swimming with an early alligator relative in the wetlands of the Western Interior Seaway in southwestern North America, during the Late ...

A previously unknown muskrat-sized mammal species was discovered through a 72-million-year-old fossil uncovered near the Utah-Colorado border.

Map of the Western Interior Seaway, which ran through Colorado and separated Appalachia from the western U.S. Sampson et al., 2010, PLOS ONE ...

This remarkable resemblance supports the existence of a three-part vertebrate community zonation for the Late Cretaceous Western Interior Seaway, a pivotal marine environment, during the early to ...

The first Pteranodon fossils, which were discovered by Marsh in 1871, were excavated from the Niobrara Formation of western Kansas, which is composed of layers of chalky limestone and shale. The ...

Geologists working in Mississippi recently stumbled upon an incredible find: the fossil of an ancient marine apex predator. On April 15, researchers were collecting rock, sediment and fossil ...

At one point, the Western Interior Seaway retreated; at another, the Rocky Mountains began to punch through North America's topography.

Map of the Western Interior Seaway, which ran through Colorado and separated Appalachia from the western U.S. Sampson et al., 2010, PLOS ONE ...

Map of the Western Interior Seaway, which ran through Colorado and separated Appalachia from the western U.S. Sampson et al., 2010, PLOS ONE ...