Microceratus

Microceratops was a tiny ceratopsian Dinosaur that lived in Mongolia about 80 million years ago, in the Late Cretaceous period. While sporting a frill like larger members of its group, Microceratops had no horns, walked on two feet, and grew to only a foot long.

In Jurassic Park
Microceratops appears only in the novel, as a free-roaming addition to the park. Some editions of the novel accidentaly replace its name with that of Callovosaurus, a small, primitive Iguanodontid.