Heloderma, the only genus of the family Helodermatidae, consists of venomous lizards native to the southwestern United States, Mexico, and as far south as Guatemala. It includes five separate species, with two subspecies. Their closest living relatives are the anguid lizards. Helodermatids are carnivorous, preying on rodents and other small mammals, and eating the eggs of birds and reptiles. They are oviparous, laying large clutches of eggs.