children underground, with Diego in pursuit. Manny, Ellie, Crash, and Eddie follow as well and discover that the icy cave leads to a vast subterranean jungle populated by dinosaurs thought to be extinct. There, they meet a deranged, quick-witted, one-eyed least weasel named Buck when he saves them from a crowd of angry, carnivorous dinosaurs surrounding them. Buck reveals that he has been living in this jungle for quite some time and is hunting down Rudy, a large and hostile albino Baryonyx feared by the inhabitants of the jungle, intending to avenge the eye he lost to him years prior. He agrees to lead the group through the jungle's perils to Lava Falls, where Momma has taken Sid and her babies. In the meantime, Scrat and Scratte continue their battle for the acorn back, but during one of their fights, Scrat saves Scratte from falling into a river of lava, causing them to fall in love with each other and forget about the acorn. Meanwhile, Momma tries to eat Sid, but her babies protect him, still thinking he is their mother. Afterwards, Momma, realizing that her children genuinely care for Sid, warms up to him. The next day, however, Sid is separated from the Tyrannosaurus family and is attacked by Rudy. He is knocked onto a loose rock slab that is floating on a river of lava and about to plummet over the falls. As the herd moves toward the lava falls, Ellie goes into labor and a pack of Guanlong attack them, causing a rock slide that separates her from the rest. Buck, Crash, and Eddie set out to rescue Sid while Manny and Diego stay behind to protect Ellie. Diego regains his edge by protecting Ellie from the Guanlong closest to her while supporting her emotionally as she gives birth, while Manny slows down the ones further away as he makes his way up to her. Meanwhile, just as Sid goes over the falls, Buck, Crash, and Eddie swoop in on a commandeered Harpactognathus, narrowly saving Sid after escaping a pack of Quetzalcoatlus. Manny reaches Ellie just in time to hear the cry of a newborn baby girl. The couple agree to name the baby "Peaches". Sid is happy to reunite with his friends, but gets sad at the fact that he never had a chance to say goodbye to the dinosaurs. Before they can leave the jungle,