Sharptooth is a term used by the characters of the film series to refer to many species of carnivorous dinosaurs and prehistoric reptiles. Chomper's parents appear to be of the real-world species Tyrannosaurus Rex. Both are green in color, the mother being a drab olive green and the father being much darker.
Chompers Parents aren't really evil despite being classified as villains. They just kill for survival since they are T-rexes as T-rexes are carnivores.
In The Land Before Time II
In the second film, they search for their missing egg, stolen by two egg-nappers, or struthiomimus, named Ozzy and Strut, and which has now hatched into a baby which the protagonist Littlefoot and friends have named Chomper. Being carnivores, the parents are aggressive towards Littlefoot and his friends. By the conclusion of the film, they are reunited with Chomper, and are last seen chasing Ozzy and Strut.
In The Land Before Time V
In the fifth film, Chomper's parents stalk the Great Valley in which the film is set, and are antagonistic hunters until Littlefoot leaps into deep water to try and save Chomper, following a battle with the Plated Sharptooth. Chomper's parents are so grateful that they promise never to harm Littlefoot or his friends.