One year after the events of the second film, Manny and Ellie are expecting their first child, and Manny struggles to make life perfect and safe for the family as he's determinated to not let his new family having the same fate his old family had. At the same time, Diego decides to leave the herd because he thinks he's losing his edge and isn't meant for the family life. Sid begins to wish for a family of his own and takes three apparently abandoned eggs that he finds in an icy cave and calls them Egbert, Shelly, and Yoko. Manny tells him to put them back, but Sid ignores him and looks after the eggs, which hatch into baby Tyrannosaurus rex the next morning. Meanwhile, Scrat encounters a female flying sabertooth squirrel named Scratte, whom he battles with over the acorn.