A collage of Arlo and Spot playing, or the "Critter" T-Rexes running.

During his journey, Arlo encounters , a wild human boy. Though initially enemies, the two form an unlikely friendship as they help each other survive. Key Characters

The leading theory involves their diet. These sauropods had a unique respiratory system (similar to birds) and swallowed gastroliths (stones) to digest massive amounts of ferns and conifers. A large gut required a large body, and a large body discouraged predators like the Giganotosaurus .