Late Cretaceous – 65 million years ago
North America: Colorado, Montana, New Mexico, Wyoming, Alberta, Saskatchewan
Despite appearances, Triceratops was no gentle, plant-eating giant. Many fossil records show damage to Triceratops bones that could have occurred in combat with rivals or predators. Aside from inter-group displays of domination and as weapons, horns could also be used in mating displays. The neck frill would have offered some protection against predatory bites (such as that of the Tyrannnosaurus rex) and may have regulated body temperature.