Buck is a major character in the 2015 Disney/Pixar animated feature film The Good Dinosaur. He is Arlo's older brother, Libby's younger twin brother, and Poppa Henry and Momma Ida's eldest son and middle child. "Buck is Arlo's brother: they're the same age, but Buck is bigger, stronger, and a little rambunctious. He likes to tease his fearful brother as often as he can—and Arlo is an easy target. Buck's size, strength, and confidence allow him to do things that Arlo can't imagine doing—like…