WALL POST

I am not someone who insists that cartoons obey the laws of physics or stick to the historical record. The Acme Corporation will not deliver a home catapult kit to an unmarked mesa in the desert Southwest, and, “Up” notwithstanding, even a modest bungalow is unlikely to make an intercontinental flight propelled solely by helium balloons. Everyone is aware of these fundamental truths, and no one is likely to complain when they are flouted for purposes of entertainment.

But the idea that a hot, verdant land, populated by giant lizards and carnivorous plants, might have lain hidden beneath the glacial, prehistoric ice — I’m sorry, but that’s just idiotic. I don’t mean to sound like a 9-year-old or a dogmatic Darwinian, but really. Come on. T. rexes chasing woolly mammoths? “Ice Age: Dawn of the Dinosaurs”? What? Dawn of the dinosaurs? In the Ice Age? You’ve got to be kidding.

I know. This kind of anachronism is trendy at the moment, what with “Year One” and “Land of the Lost” and “Star Trek.” But weren’t underground dinosaurs in 3-D already tried last summer in the abysmal “Journey to the Center of the Earth”? Couldn’t the creative minds at the 20th Century Fox animation studios, hoping to wring a few hundred million dollars more out of their prized family-animation franchise, have come up with something more original?

Dumb question. The first two “Ice Age” movies were widely tolerated by adults and children alike, and while nobody has necessarily been clamoring to sample more prehistoric voice work from Ray Romano, Denis Leary, Queen Latifah and John Leguizamo, families who have recovered from the trauma of the “Transformers” sequel are unlikely to avoid this tired, loud little sequel over the coming holiday weekend.

The story, such as it is, concerns the expanding family circle of the mammoths Manny (Mr. Romano) and Ellie (Ms. Latifah) and their sidekick pals. Ellie is expecting a baby, which inspires the envious sloth Sid (Mr. Leguizamo) to adopt three mysterious eggs he finds in a cave. When they hatch into cute little rambunctious baby dinosaurs, the whole crew — including the opossums Crash (Seann William Scott) and Eddie (Josh Peck), ancillary, annoying comic sidekicks, just in case Sid’s energy should falter — takes a subterranean voyage into a land of biological diversity and creative desolation.

Not that stuff doesn’t happen. A new, nutty sidekick is discovered, a weasel named Buck, who has an eyepatch, the swashbuckling accent of Simon Pegg and the funniest lines in the movie. And though I might have dozed off, I think some important lessons were dispensed about being yourself, sticking together, following your dreams and accepting the inevitable extinction of your species. Maybe not the last one, come to think of it, and since future sequels are likely, it would be premature in any case.

As in the previous installment (also directed by Carlos Saldanha), one element of “Ice Age: Dawn of the Dinosaurs” manages to be authentically charming, and also to make moderately ingenious use of the 3-D techniques that otherwise just add to the jostle and noise. I’m referring, of course, to the dialogue-free sequences, unrelated to the main plot, that involve a plucky proto-squirrel known as Scrat and his quixotic pursuit of an acorn. This time Scrat is distracted by love, and he and his inamorata, who is also his rival for possession of that acorn, breath whimsical, inventive life into the movie.

They also expose its pointlessness and irrelevance. A collection of short Scrat films would be much more pleasing than the elephantine “Ice Age” series, though of course without the same commercial potential. But silliness and simplicity are, in the end, worth more than overblown dinosaur chases or cynical, recycled life lessons, and children’s animation does not require an extra visual dimension or additional celebrity voices as much as it needs an occasional reminder of the value of keeping silent.

“Ice Age: Dawn of the Dinosaurs” is rated PG (Parental guidance suggested). It has some scary scenes of cute creatures being chased by predators.

Ice Age Dawn of the Dinosaurs

Opens on Wednesday nationwide.

Directed by Carlos Saldanha; written by Michael Berg, Peter Ackerman, Mike Reiss and Yoni Brenner, based on a story by Jason Carter Eaton; characters designed by Peter de Sève; edited by Harry Hitner; music by John Powell; art director, Michael Knapp; produced by Lori Forte and John C. Donkin; released by 20th Century Fox. Running time: 1 hour 27 minutes.

WITH THE VOICES OF: Ray Romano (Manny), John Leguizamo (Sid), Denis Leary (Diego), Simon Pegg (Buck), Queen Latifah (Ellie), Seann William Scott (Crash) and Josh Peck (Eddie).

review fromThe New York Times