Hooves are present in several groups of mammals, including the Artiodactyla, the diverse order that includes cattle (bovids) and an enormous range of other animals. Bovids, including bison, have only two toes on each foot, with a hoof at the tip of each toe, as is clear in the photo below of a bison considerately presenting his hooves for inspection:
The outside of the hoof is made largely of keratin proteins, but inside is a bone. This is the last finger or toe bone, known as the terminal phalanx or ungal. The ungal shown above appears to be from left manual digit IV, or the outside toe on the left forefoot. This specimen was collected from the East Dam of Diamond Valley Lake, not far from where the Western Science Center is now located.