he Museum's tradition of excavating, studying, and exhibiting fossil mammals has an even longer and more illustrious history than its work with dinosaurs. The Museum's first expedition to search for such fossils was launched in 1891, and in 1895, before its scientists had found a single dinosaur, the Museum opened a full-scale hall of fossil mammals. This original hall, which has displayed such specimens continuously since then, now features advanced mammals with such traits as hoofs and eye sockets near the snout, in addition to those traits featured in the Hall of Primitive Mammals. A wide range of animals is represented along these evolutionary branches, including cats, seals, bears, primates, horses, whales, and elephants, along with their extinct relatives. Up until about 10,000 years ago, mammoths, mastodons, saber-toothed cats, camels, and giant ground sloths roamed across North America. Then, an episode of extinction wiped all those animals out. The cause of this wave of extinction is unclear, but possible explanations include dramatic climate changes at the end of the last ice age, hunting by humans, and infectious disease.

Learn more about the Fossil Halls.