Prehistory's first blended herd — sloth Sid (voice of John Leguizamo), mammoth Manny (Ray Romano) and saber-toothed tiger Diego (Denis Leary) — begins a new adventure some tens of thousands of years after joining forces in the face of a global deep freeze (no, the math doesn't work, so stop worrying about it). Worldwide warming is melting the Earth's mantle of ice, and none of its creatures wants to imagine a downside until a dour vulture (Will Arnett) hits them with some unassailable logic: They're in a valley, and when the surrounding glaciers melt, anything without gills or wings will be up an evolutionary creek without a selective adaptation. But the vulture claims to have seen a boat, and so a new migration begins. As if tromping over hill and dale pursued by the specter of imminent death (personified by two scaly sea predators who glide unnoticed beneath the thinning ice) weren't enough, big 'fraidy cat Diego is secretly hydrophobic, and morose Manny suspects he's the sole surviving member of his species (a grim notion reinforced every time some insensitive lesser life form scuttles by and marvels, "Look kids, the last mammoth!"). Fortunately for Manny, they soon cross paths with Ellie (Queen Latifah), as fine a specimen of wooly pulchritude as anyone could imagine — except for the fact that she thinks she's an opossum — who comes encumbered with a pair of smart-mouthed, hyperactive 'possum "brothers" (Seann William Scott, Josh Peck) and takes Manny for a clueless masher. They work out their differences around the same time Diego is forced to face his fears from the vantage point of a runaway ice floe, while Sid just ambles along being Sid and initiating the movie's two musical numbers: a Busby Berkeley-style synchronized spectacle involving miniature, pastel-colored sloths who take Sid for a fire god, and a very funny, vulture-specific variation on OLIVER!'s "Food, Glorious Food." The series' breakout star remains Scrat (Chris Wedge), a scrawny, speechless rat-squirrel thing trapped in a Sisyphean quest for acorns, and while kids' movies generally could do with fewer scatological gags (the target audience for poo and pee humor needs no encouragement), writers Peter Gaulke and Jim Hecht managed to come up with a (relatively) sophisticated one: Father dung beetle, rolling a manure ball twice his size and sighing that they probably have the same crap wherever they're going, is silenced by his wife's brisk rejoinder that this ball of dung was her mother's. And that's the end of that. --Maitland McDonagh
