After the events of "Ice Age: The Meltdown", life begins to change for Manny and his friends: Scrat is still on the hunt to hold onto his beloved acorn, while finding a possible romance in a female sabre-toothed squirrel named Scratte. Manny and Ellie, having since become an item, are expecting a baby, which leaves Manny anxious to ensure that everything is perfect for when his baby arrives. Diego is fed up with being treated like a house-cat and ponders the notion that he is becoming too laid-back. Sid begins to wish for a family of his own, and so steals some dinosaur eggs which leads to Sid ending up in a strange underground world where his herd must rescue him, while dodging dinosaurs and facing danger left and right, and meeting up with a one-eyed weasel known as Buck who hunts dinosaurs intently.
Cast:
- Eunice Cho - Diatryma Girl (voice)
- Karen Disher - Scratte (voice)
- Harrison Fahn - Glypto Boy (voice)
- Maile Flanagan - Aardvark Mom (voice)
- Jason Fricchione - Adult Molehog Male (voice)
- Bill Hader - Gazelle (voice)
- Kelly Keaton - Molehog Mom / Shovelmouth Mom (voice)
- Joey King - Beaver Girl (voice)
- Queen Latifah - Ellie (voice)
- Denis Leary - Diego (voice)
- Allegra Leguizamo - Aardvark Girl (voice)
- John Leguizamo - Sid (voice)
- Lucas Leguizamo - Aardvark Boy / Beaver Kid #2 (voice)
- Clea Lewis - Start Mom (voice)
- Jane Lynch - Diatryma Mom (voice)