Ice Age: Dawn of the Dinosaurs opens with the stitched-together prehistoric family about to become a biological one: Manny (voiced by Ray Romano) and his mate Ellie (Queen Latifah) are expecting a baby mammoth. Unfortunately, this makes Sid the sloth (John Leguizamo) and Diego the saber-toothed tiger (Denis Leary) feel left out. Diego, who worries he’s losing his edge, decides to head out on his own, while Sid adopts three suspiciously large eggs that he’s found through a crack in the ice. Up to this point, the movie is perilously sappy--does anyone, particularly a kid, want to watch a kid’s movie about parenthood and impending middle age? Fortunately, the eggs turn out to be dinosaur eggs from a pre-mammalian underworld, and when the mama T-Rex comes to rescue her rambunctious little ones, Ice Age: Dawn of the Dinosaurs transforms into a delightful comic adventure. The emotional side of the Ice Age movies has always been a tad mawkish, so it’s smart that Dawn of the Dinosaurs emphasizes physical comedy. Clearly, the animators have been inspired by a wild fusion of Road Runner cartoons and Buster Keaton. The character of Scratte, with his non-verbal, monomaniacal efforts to get that last acorn (doubled in this movie with the addition of a female counterpart), is only the most obvious reflection of this sensibility. The animators have great fun with the differences in scale between the mammals and the dinosaurs, and the introduction of a deranged Australian weasel named Buck (Simon Pegg, Shaun of the Dead) pushes everything into Loony-Tune territory. Let Pixar tug at our heartstrings; Ice Age aims to tickle the funny bone and does a fine job of it