Emma Stone, Nicolas Cage, Ryan Reynolds, Catherine Keener, Cloris Leachman, Clark Duke

Kirk De Micco & Chris Sanders

If this movie had a plot, it would be dangerous. As it is, “The Croods” is a rough sketch of an idea, kept afloat courtesy of some well-timed gags. It has heart and a fair share of laughs, and it’s hard not to like the message that we must evolve as a species if we intend to survive, but it feels like a sitcom episode stretched out to a grueling 98 minutes. Ninety-eight-minute movies aren’t supposed to feel long. This one does.

The Croods are a family of cavepeople who have outlived their Neanderthal contemporaries by playing it very, very safe. The father Grug (Nicolas Cage) insists that everyone stay near their cave, and to never leave the cave at night, much to the chagrin of his curious daughter Eep (Emma Stone). One night, unable to sleep, Eep sees a flickering light outside the cave. She sneaks out to investigate, and meets Guy (Ryan Reynolds), a homo sapien boy who warns her that the world is coming to an end (it’s actually continental drift), and that she and her family must find better, higher ground if they wish to survive. This idea, of course, does not sit well with Grug, but it is not long before Guy is proven right, which creates, in Grug’s mind anyway, a battle for supremacy between brains and brawn.

This is the kind of movie that sweats the small stuff – the disaster sequences will make Roland Emmerich squeal, and the animals they created, especially the piranha birds, are both amusing and inspired – but for some reason, they don’t put the same effort into the story. It gets to the point where they let Cage off his leash (never a good idea) and do this bit where Grug tries to be a thinker like Guy, only Cage sounds like he’s trying to channel Jeff Bridges in “The Big Lebowski.” On the one hand, it’s kind of fun to see an animated film play it loose and experiment. On the other hand, it feels forced and out of step with everything around it.

They sure did a nice job of casting the film though, rounding out the A-list firepower with indie queen Catherine Keener, funnyman Clark Duke, who makes a very forgettable character memorable, and Cloris Leachman as Keener’s mom, though to be fair most of Leachman’s laughs come from her character’s actions rather than her words (she’s good with a stick). In spite of these nice touches, “The Croods” is too underdeveloped to pose a threat to its modern-day animated peers. Insert your own joke here about the caveman movie suffering from a lack of development.