triceratops

Triceratops is Greek for "three-horned face," but this dinosaur actually had only two genuine horns; the third, a much shorter "horn" on the end of its snout, was made from a soft protein called keratin, the kind found in human fingernails, and wouldn't have been much use in a tussle with a hungry raptor. Paleontologists have identified the remains of a two-horned dinosaur called Nedoceratops, but it may represent a juvenile growth stage of Triceratops.