Buck Wild
Buck first met Manny, Crash, Eddie, Diego, and Ellie (who he at one point refers to as "preggers") after they descend into the jungle in pursuit of Sid and Momma, and saves them from a dinosaur attack. He has been living in the jungle for quite some time, persistently hunting Rudy to avenge the loss of his eye, and agrees to lead them to Lava Falls, where Momma has taken Sid, and rescues him after taking control of a Harpactognathus. After Rudy's potential death, Buck, having lost his purpose in life, decides to join the herd and live on the surface. Upon hearing a distant familiar roar that tells him that Rudy survived the fall, he chooses to stay and causes a cave-in that seals off the path between the surface and the underground jungle, trapping him inside and everyone else on the surface. He and Rudy proceed to continue their battle.