Microceratus is a bipedal ancestor of the horned dinosaurs such as Triceratops. Despite not being very large, at least one is shown to be aggressive towards smaller animals, such as the Ceratogaulus colony.
Microceratus in The Land Before Time
A Microceratus terrorizes a Ceratogaulus burrow in "Stranger from the Mysterious Above" (possibly due to an inferiority complex to larger dinosaurs). Spike ends up frightening it away, saving the mammals.
- Why the herbivorous Microceratus would attack a group of Ceratogaulus is unknown.