"The Croods" opens with rebellious teen daughter Eep (voiced by Emma Stone) speaking in voiceover about her family's trials and travails as one of the first families of cavemen to roam the planet. How would she even know the term "cavemen," which probably wasn't created until thousands of years later? It is best to not think so hard about such logistics, and instead mourn that the participation of Emma Stone (2013's "Gangster Squad") is where the inspiration within this distaff computer-animated feature from Dreamworks begins and ends. For a minute or two of her delightfully acerbic narration, she reminds of her unforgettable heroine, Olive Penderghast, from 2010's "Easy A." Once that's finished and the rest of the film proper gets underway, "The Croods" plummets into terminal mediocrity, marked by dull, flat-footed characters, rote pacing, a conflict in desperate need of a more clear-cut villain, and the kind of murky, worthless 3D that only hinders the visuals and gives the 3D format a bad reputation.

The Croods—overbearing father Grug (Nicolas Cage), patient mother Ugga (Catherine Keener), aforementioned daughter Eep, offbeat 9-year-old brother Thunk (Clark Duke), toddler Sandy (Randy Thorn), and rambunctious Gran (Cloris Leachman)—have managed to survive the dangerous animals and elements of the Paleolithic Era by cooping themselves up in their cave whenever danger seems to be getting close outside. Seemingly the last family of their kind to not be wiped out by natural selection, Eep grows ever curious to see what the rest of the world has to offer and is lured away one night by the glow of a fire started by a slightly more advanced caveboy named Guy (Ryan Reynolds). The rest of the family are soon right behind them, thrust into a landscape they have yet to discover. With Guy warning them that the threat of volcanoes and seismic earthquakes will surely wipe out their old cave, they set out for safer ground and a new place to call home. Grug, who is constantly wary of anything different or new, is especially slow to come around as they head for the sun on the horizon. However, by the end of their journey, he is sure to realize that it is Eep's adventurous spirit that may very well have saved them all.

Maybe "The Croods" will play better at home, on Blu-ray and in glorious two dimensions. In theaters, where it is being shown in a pointless, chintzy, brightness-draining 3D presentation, the picture looks ugly, dim, and overly brown. A long way from the impressive 3D used to give scope and depth to the recent "Oz the Great and Powerful," taking off one's glasses for any period of time here suddenly reveals a vibrancy to the image that is severely lacking once the spectacles are put back on. A distinct disservice to the fastidious hard work and talents of its animators, studio Dreamworks ought to be ashamed of themselves for not giving audiences a solitary reason why they would want to choose the 3D presentation—then, at many theaters, forcing them to see it in this subpar way for an insulting pricey surcharge.

Lacking variety in its sights—the first half of the movie is set largely amidst nondescript rocks and boulders—perhaps the story will level out the weak areas and breed imagination? Not a chance, as long as the greenery, red fluttering insect swarms, and various increasingly tedious creature chases look so much like copycat retreads of 2009's "Avatar." As for the Croods themselves, only Emma Stone's go-getter Eep ever comes to life. The rest of the family members never quite form a believable or warm-hearted unit, their bickering usually getting in the way of character and relationship development. As Grug, Nicolas Cage (2012's "Ghost Rider: Spirit of Vengeance") is stuck playing the gruff dad who takes the length of the movie to come around and not take his daughter for granted. As his wife Ugga, the usually can't-miss Catherine Keener (2012's "Peace, Love & Misunderstanding") misses big time, a victim of vocal miscasting and a character whose defining traits could be counted on a badly mangled hand. As for Cloris Leachman's Gran, the obvious joke is missed—that in this time period, she is all of 45 and considered ancient—in place of a distasteful running gag where Grug keeps getting his hopes up that she's died, only for her to pop back up unscathed.

"The Croods" was written and directed by Kirk De Micco (2008's "Space Chimps") and Chris Sanders (2010's "How to Train Your Dragon"), and it only takes a gander at some of the stronger, more vividly written and envisioned animated films of the last few years—for example, "ParaNorman," "The Lorax," and "Rango"—to reveal just how deficient and stale this project is. It's never funny or all that emotional, and there is barely a connection to latch onto when it comes to the clumsily one-note protagonists. The finale, at last, earns a bit of tension when the Croods and Guy must escape a ground that is falling out from them, and there is a surprise in its reveal of how the first domesticated pets came to be, but these things bring too little and come too late to the proceedings to turn around the film's overall sluggishness. "The Croods" is 2013's first major animated tentpole release, and, as such, it will hopefully only be uphill from here.