A mild bounce back from the dinosaur doldrums of the last Ice Age movie. When the earth’s surface splits apart, Manny the family-guy mammoth (Ray Romano), Diego the saber-toothed tiger grouch (Denis Leary), and Sid the infantile sloth (John Leguizamo) get stranded on an ice floe in Ice Age: Continental Drift. They’re trying to get back home — a dreary plot, but the film keeps throwing things at you, like a colorful ape pirate (Peter Dinklage) and a fun hallucination sequence. That said, the laughs are starting to feel prehistoric. B