The Croods is but a pleasantly entertaining 3-D animated film, so it comes as a disappointment to discover that it was co-written and co-directed by Chris Sanders, the brain behind the sublimely delightful Lilo & Stitch and How to Train Your Dragon. Then again, Sanders shares credit with Kirk De Micco, who gave us the forgettable Space Chimps.

Having not witnessed who wrote what in the screenplay, it’s unfair to guess who wrote the good scenes in The Croods and who wrote the bad ones. Every now and then, the movie achieves some quiet moments where it becomes something more than a child’s amusement.

The tale concerns a family of cavemen who believe themselves to be the last homo sapiens on Earth.

As young Eep (voiced by Emma Stone) laments in the voice over, it’s an existence that alternates between dull routine and frantic chases. Despite her father Grug’s strict orders, Eep wanders around looking for a more fulfilling existence.

Grug (Nicolas Cage) may be overly adamant about the need to live in fear, but considering the fact that there are no other humans and an endless number of hungry predators, it’s unfair to call him paranoid. That’s probably why mother Ugga (Catherine Keener), grandmother Gran (Cloris Leachman), brother Thunk (Clark Duke) and baby sister Sandy (Randy Thom) simply go along with Grug’s dictates.

Eep’s wanderlust may irritate her father, but it leads her to a delightful but urgent discovery. There’s another human living outside the cave named Guy (Ryan Reynolds).

Having seen more of the world, Guy appears to know a great deal about it and winds up disturbing Grug when he reveals that the days of simply hiding in caves are passing. The older man’s family realizes that change is coming quickly, but Grug’s stubbornness threatens them all with extinction.

Grug is a tonic for Cage’s struggling career. As a cartoon caveman, Cage’s tendency to bellow is appropriate. Here the outbursts sound strangely natural.

De Micco and Sanders make one fascinating decision that helps the rest of the film move along. Because nobody living remembers what prehistoric animals looked like, the two avoid creatures that are in the skeletal record and opt for exotic make-believe critters that exist only in the film itself.

Fortunately, De Micco and Sanders do something that isn’t usually seen in children’s cartoons. Grug is a loving father who unfortunately has some limited ideas. But his creators never demonize him. In this prehistoric world, there are no bad people, just bad ideas.

The Croods 79 Cast: With the voices of Nicolas Cage, Emma Stone, Ryan Reynolds, Catherine Keener, Cloris Leachman, Clark Duke, Chris Sanders, Randy Thom Directors: Kirk De Micco, Chris Sanders Rating: PG, for some scary action Running time: 98 minutes

MovieStyle, Pages 33 on 03/22/2013