Triceratops are seen once in Ice Age 3. There are three of them, two parents and a baby. (With a large frill mistake of a Chasmosaurus) They are wading through a pond, but the young one is distracted by a lily pad. It was going to play with it, but one of the parents grunted, telling the baby to catch up. It did, and after they left, Buck emerged from under the lily pad.