Bison in the Pleistocene Epoch (2.6 million to 11,700 years ago) had horns spanning nearly 10 feet tip to tip, making them significantly larger than modern bison (the Kansas state mammal).

Fossils of Pleistocene and later Holocene bison are most commonly found near riverbeds. Along Bear Creek in western Kansas, for example, archaeologists found fossilized bones of at least seven bison that lived about 9,000 years ago. Human artifacts found in the bone bed proved that PaleoIndians (early people in North America) hunted, butchered, and cooked the bison.