Dirs: Chris Wedge, Carlos Sladanha. US. 2002. 81 mins.

It may not have the stuff to top - either commercially or creatively - Shrek and Monsters, Inc, but with its impressive computer animation, appealing characters and well-crafted blend of comedy, action and drama Ice Age certainly has the necessary ingredients to give Fox a long-awaited major animated hit. Produced, as its debut feature, by Fox's Blue Sky Studios, the film has generated pre-release buzz through its delightfully slapstick trailer. Now it will be up to Fox - which has begun by securing a slew of promotional tie-ins and inserting Ice Age characters into a range of TV programming - to prove that it can market the finished product to kids and their families as efficiently as DreamWorks and Disney did with last year's two computer-animated blockbusters.

Director and Blue Sky co-founder Chris Wedge won an Oscar in 1999 for his animated short Bunny. Here, he uses the company's proprietary lighting software, known as Ray Tracing, to depict a sweeping early-ice age landscape and the menagerie of animals - from prehistoric rhinos to scrawny mammals, though no dinosaurs - that inhabits it. The technique works particularly well on the giant glaciers and icy caverns that are encroaching on the creatures' once green world. Most of the animation effort, however, goes into the film's three heroes: misanthropic but good-hearted woolly mammoth Manny, voiced by Ray Romano (from hit sitcom Everybody Loves Raymond); comical sloth Sid, voiced by Broadway and movie performer John Leguizamo; and sinister sabre-toothed tiger Diego, voiced by Denis Leary (The Ref).

Besides providing the creatures with the naturalistic fur that has come to be the computer animator's calling card, the animation gives Manny an effectively lumbering presence and nicely expressive eyes and turns Sid into a buck-toothed, rubber-limbed comedian. Diego and the film's other animal and human characters are more stylised - possibly for financial reasons, though the film's budget has been estimated at a healthy $75m - and somewhat less effective.

The plot is fairly standard for the genre, containing echoes of both Shrek and Monsters, Inc. While most of the creatures are heading south to escape the oncoming ice, contrary Manny is heading north. Sid, who has slept through the start of the migration, adopts Manny as a reluctant protector and when the partners find a lost human baby they form an uneasy alliance with Diego and set out to return the baby to its 'herd.' Trekking across perilous icy wastes and lakes of volcanic lava, and tangling along the way with a pack of vicious tigers, the three misfit animals eventually learn to look out for each other, forming an unlikely mini-herd of their own.

Though the momentum of the drama occasionally lags, the film does manage to end on a suitably moving note. It's the comedy, however, that give Ice Age most of its appeal.

With its towering cliffs and glaciers, the setting provides plenty of opportunity for slapstick humour recalling the drawn animation work (particularly the Road Runner cartoons) of the recently-deceased Chuck Jones. To make the most of the opportunity, Ice Age has Scrat, the non-verbal half-squirrel, half-rat creature featured in the film's trailer, appear at regular intervals on his never ending quest to find a hiding place for a precious acorn. As well as starring in the film's opening sequence (an expanded version of the trailer), Scrat also features in a cute epilogue to the main action. Other creatures, including a hyperactive flock of doomed dodos, provide additional comic relief.

Among the voiceover performers, Romano is fairly subdued as the grumpy, sarcastic Manny but Leguizamo, whose vocal abilities have been spotlighted in several hit one-man stage shows, goes to town as the lisping, motor-mouthed Sid. The comedy is nicely accentuated by a quirky music score from composer David Newman (The Flintstones).

Prod co: Blue Sky Studios.
Dist: 20th Century Fox.
Prod: Lori Forte.
Exec prod: Christopher Meledandri.
Scr: Michael Berg, Michael J Wilson, Peter Ackerman.
Music: David Newman.
Prod des: Brian McEntee.
Ed: John Carnochan.
Main cast (voices): Ray Romano, John Leguizamo, Denis Leary, Goran Visnjic, Jack Black, Tara Strong.