Some of the most commonly seen animals during summer in the monument are reptiles, especially lizards. During winter months, reptiles may hibernate, or in the case of snakes, will den up together in a rocky cave and go into an inactive torpor.
Western rattlesnakes live throughout the Fossil Beds and can be dangerous, though they tend to shy away from people by heading off before they are seen. If surprised or threatened though, they will sound the rattling noise they are named after. Most snakes in the monument are other varieties that pose no threat, such as garter snakes, gopher snakes, and blue racers.
Snakes play a significant role in controlling rodent populations. Lizards help keep insect populations in check. Even those who do not particularly like reptiles benefit from their presence.