Twentieth Century Fox's animation division finally hits it big with Ice Age, a clever and beautifully designed computer animated feature that often measures up to the standards set by last year's two CGI blockbusters, Shrek and Monsters, Inc. Like a prehistoric remake of the classic John Ford western Three Godfathers, Ice Age centers on three nomads forced to care for an abandoned infant. In this instance, the trio consists of Manny, an antisocial woolly mammoth; Sid, a hapless, conniving sloth; and Diego, a ruthless saber-toothed tiger. As the Ice Age begins some 20,000 years ago, Manny heads north while the rest of the mammal population migrates southward; much to his annoyance, he's joined by Sid, who has angered some rhinos and is in urgent need of the mammoth's protection. Manny the loner gets more unwanted company when Sid finds a Native American baby whose mother has been killed. Soon, they encounter Diego, who has been sent by his pack to retrieve the infant. But Manny, more soft-hearted than he first appears, has no intention of sacrificing the child. The unlikely trio sets off in search of the baby's tribe, with the scheming Diego as their tracker.

Directed by Chris Wedge, who won an Oscar a few years ago for the CGI short Bunny, Ice Age maintains a difficult balance of flat-out physical comedy and genuine heart. Every five minutes or so, there's a terrific action-comedy set piece: an encounter with a flock of dopey dodos who quickly demonstrate why their species no longer exists; a breathless, high-speed ride through a series of ice funnels; a daring escape over a collapsing ice bridge. Manny, who begins the film as a misanthrope, makes a genuinely touching emotional journey, especially after it's revealed that the baby's tribe has slaughtered his own kind. Diego, too, evolves from heartless predator to hero in convincing fashion.

The dry deadpan of Ray Romano, star of the consistently hilarious TV sitcom "Everybody Loves Raymond," makes an ideal match with the much-put-upon Manny. John Leguizamo lends his hyperactive rhythms (plus a lisp) to the lovably annoying Sid, and Denis Leary brings a welcome taste of his cynical gruffness to the conflicted tiger. Other familiar voices include "ER" star Goran Visnjic, Jack Black and Cedric "The Entertainer."

Evoking the work of the late, great Chuck Jones, Ice Age also includes a delightful series of gags involving "Scrat," a squirrel-rat hybrid whose efforts to hang onto a single acorn invariably lead to disaster--including the commencement of the Ice Age itself. Don't exit the theatre too early--the closing kicker with Scrat is among the funniest jokes in the movie.

Purely on the design level, Wedge and his team at Blue Sky Studios make a dazzling feature debut, with gorgeously palpable wintry settings, painstaking lighting effects, and witty character movement and expressiveness. For Fox and its feature animation ambitions, the big thaw has arrived.

-Kevin Lally