Skeletal remains of this early horned dinosaur were first discovered in Mongolia in the 1920s. Since then, hundreds of skulls and skeletons of Protoceratops, ranging from hatchlings to adult males and females, have been collected.

Although hornless, Protoceratops shared with later horned dinosaurs such as Triceratops a distinct bump above the nostrils and a large bony frill that extended over the neck. Thickened areas of bone just above the eye sockets reflect the locations where horns would appear in later horned dinosaur species. Strong cheek muscles prevented food from escaping the mouth during feeding.

Protoceratops is also known for the many nests of its eggs which have been discovered in Mongolia.  These nests included Protoceratops of many ages, including babies that had not yet hatched. However, some eggs originally thought to be those of Protoceratops are actually those of other kinds of dinosaurs.

The andrewsi in Protoceratops' name was bestowed in honor of American explorer Roy Chapman Andrews.