This third in the Ice Age series is a bit sweeter and gentler than the first two, perhaps less ambitious in scope than the first but much more engaging than the second. The 3D animation is beautifully immersive and the story is exciting but so low-key that everyone, even the scary dinosaurs with the big teeth, ends up happy.

Again this is the story of woolly mammoth Manny (Ray Romano), sloth Sid (John Leguizamo), and saber tooth tiger Diego (Dennis Leary), now joined by Manny’s mate Ellie (Queen Latifah), who is about to have a baby. Everything seems settled and happy, but of course we would not have a story unless everything got unsettled pretty quickly. Diego is feeling left out and worried about getting older and less powerful, so he decides to leave the makeshift “tribe” they all think of as family. Sid finds three huge eggs and immediately adopts them, his nesting instinct so over the top that he insists he is their mother. The eggs hatch, and at first the little dino babies happily follow Sid around like ducklings, though they are not entirely on board with the idea of vegetarianism. But then their mommy dinosaur comes to get them, grabbing Sid along with her chicks, and pending childbirth or not, Sid, Manny, Ellie, and Diego go off to rescue him.

They end up in an underground portal to a place where the weather is temperate and the dinosaurs still rule. “I thought those guys were extinct,” one of our heroes comments. (Note that in real life the last Ice Age was about 20 thousand years ago and the last dinosaurs were about 65 million years ago, but what the heck, animals do not talk or build playgrounds, either.) There they meet up with an off-beat piratical weasel named Buck (Simon Pegg), who teaches them some survival skills and leads them to Sid. Along the way, they have a number of adventures, and yes, that baby decides to arrive at just the wrong place and time, but despite some chases, several falls, and one near-ingestion by a hungry plant, everyone ends up happy and healthy.

Children and their parents will enjoy the portrayals of family life. “You’re trying to childproof nature,” Ellie chides Manny as his approaching fatherhood brings literally home to him the dangers of the world. And they will enjoy Buck’s rakish antics and the traditional subplot about the prehistoric squirrel Scrat and his perpetual quest for the elusive acorn. This time, his biggest impediment is a long-lashed female, who outsmarts him at every turn.

Scrat’s romantic confusion is a lot of fun, but there is a sense that the folks behind this movie are not evolved enough to think of the female characters as anything other than wise and nurturing — and a little bossy. Ellie’s job in the movie is to be the grown-up; apparently even in pre-historic times the females were more, uh, evolved. Not as funny, however.

But the sweet nature of this film is engaging and the adorable characters designed by illustrator Peter de Seve make this movie both satisfying and fun. The squirrels’ tar pit dip, romantic tango, and post-romantic home-decorating session, Sid’s efforts to mother the adorable dinosaur babies, and a nimble balance of action and humor make this one of the best family films of the year.