He first appeared as the deuteragonist of The Land Before Time II: The Great Valley Adventure, when he was hatched by Littlefoot. Being raised by them for the first day of his life has led him to be friendly with herbivorous dinosaurs, although they do not always trust him. But his friends still like him anyway. He is bilingual, being able to speak both the herbivore language of the plant-eating dinosaurs (heard as English to the viewer), and the "Sharptooth" language of the carnivorous dinosaurs, which seems to consist of grunts, roars, and clicks, which makes him quite useful in solving disputes between the herbivores and carnivores.
Chomper was so well-received by the fans and critics of the series that he was brought back as a major character in The Land Before Time V: The Mysterious Island, and re-introduced as a main character in the television series. He returned as a supporting character in Journey of the Brave.
Chomper is kind and extroverted. But he is also a little naive when he sometimes offers insects to his friends, forgetting that they are herbivores. Chomper is always loyal to his friends, it hurts him so much that his friends do not trust him a lot on occasion for being a sharptooth, something that once Cera expressed her distrust of by openly hurting his feelings in the fifth movie. Littlefoot and Ruby are the only ones who trust Chomper without hesitation, so the two are known as the closest friends of the young tyrannosaur.
Chomper hates to be called small even if it is or also that his arms are very short. He also does not like to feel useless when he tries to help his friends, just as his short arms do not allow him to push heavy rocks.