Hall of Ancient Life: Cenozoic Era

65 million years ago to the present

By the Cenozoic Era, the landmass of North America had taken on a fairly "modern" look, though Florida was still underwater. The inland sea that had covered Oklahoma during the Cretaceous Period had receded, leaving Oklahoma once again at a distance from the ocean.

After the mass extinction that eliminated all the dinosaurs except birds, many habitats were nearly emptied of large animals. However, over a relatively short period of time (geologically speaking), mammals filled those gaps, growing in size (like mammoths and whales) and in diversity (primates, rodents, hoofed mammals, etc.).

Arctodus

Around eight million years ago, Oklahoma's landscape changed dramatically. The flowering plants that had evolved in the Cretaceous Period were transforming the world. New plants, along with major climate changes in the middle Cenozoic, resulted in more open habitats, especially grasslands. Many animals adapted to these changes by evolving specialized features such as long legs for running across the plains.

The Pleistocene Epoch, 1.8 million to about 11,500 thousand years ago, is known as the Ice Age because it was characterized by cycles in which great ice sheets expanded and contracted, at times covering as much as a third of Earth's surface. Though the ice never reached as far south as Oklahoma, the climate and animal life were very different than they are today - cooler and drier as the ice moved southward, with greater seasonal changes than before.

Mammoths, mastodons, giant bison and ground sloths fed on plants. They were preyed upon in turn by sabertooth cats, the enormous short-faced bear Arctodus, and dire wolves that were much larger than modern wolves. An exhibit in this gallery illustrates what happens when a sabertooth cat and a short-faced bear stumble across the same meal.

Gomphotherium

Around 12,000 years ago, Oklahoma was home to two different mammoths: the woolly mammoth and the Columbian mammoth, which was much more common. Mammoth fossils are found all over Oklahoma, but especially in the west. You can see a fully mounted skeleton of a Columbian mammoth from Oklahoma in these exhibits, as well as an earlier elephant relative, the "prod tusker" Gomphotherium, from the Paleogene Period.

Some 10,000 years ago, most of the "megafauna," or large animals of this time, including as many as 30 types of mammals, became extinct in North America. This may have been due to an inability to adapt to the dramatic climate changes between colder periods of glacial expansion and warmer "interglacial" periods.

Sometime between 30,000 and 15,000 years ago, humans became part of the scene in Oklahoma as well. The earliest known humans in the area, the Clovis people, lived among many of these fearsome Ice Age mammals. They hunted the giant mammoth and depended upon it for food, shelter, tools and clothes. Heavy hunting by humans may have contributed to the extinction of the mammoth and other animals. You can view a life-sized pair of sculptures depicting an encounter between humans and a giant Columbian mammoth in the museum's Pleistocene Plaza.