Rowdy, trippy and surprisingly raunchy, "Land of the Lost" pushes sci-fi/comedy to the edge of PG-13 decorum.

It's based on a kitschy 1970s live action children's series created by Sid and Marty Krofft (creators of "H.R. Pufnstuf" and "Lidsville"). The Kroffts have spent decades denying that they made their loopy, special-effects-heavy shows under the influence of recreational chemicals. The people behind this leave-your-brains-at-home film might make the same claim, but I'm withholding judgment until I see the lab tests.

Will Ferrell stars as Dr. Rick Marshall, a "quantum paleontologist" who dresses like a park ranger and behaves like a spoiled, immature doofus. When Matt Lauer of "The Today Show" questions his claim that our energy crisis can be solved with transdimensional portals, Rick charges the host, windmilling punches.

Demoted to teaching kiddie science classes at the La Brea Tar Pits, he's a bitter laughingstock until science babe Holly Cantrell (Anna Friel) insists he complete his research. The likeliest gateway to an alternate reality is located in a cheesy roadside amusement park run by Will, a macho redneck tour guide (Danny McBride).

Before you can say "wormhole," the trio is running from angry dinosaurs, reptilian aliens and giant mosquitoes on a wild, wild planet.

It's a vast desert littered with Viking longboats, midcentury motels, pterodactyls, Cessnas and the occasional medieval catapult, the sort of stuff you might find in the Bermuda Triangle's sink drain. Their guide is Chaka (Jorma Taccone), a missing-link teenager who chatters a nonsense language and knows which trees bear the most consciousness-altering fruit.

This isn't the "Land of the Lost" you remember from childhood, but get on its antisocial wavelength and it's fitfully laugh-out-loud funny. The film seems to have been written on the fly, torn apart and roughly put back together. Director Brad Silberling chooses oddball perspectives on the action, shooting the actors as fly specks on the horizon or running alongside them as they race from danger.

The film is so packed with scatological humor you keep looking for the Charmin product placement. Still, I give it points for its subversive, psychedelic absurdism, a choice that will annoy at least as many viewers as it attracts. It's such a skewed, quirky misfire that I found its idiocies oddly entertaining.

Mainstream summertime action fantasies are about ordinary people coping with extraordinary events. "Land of the Lost" spins the innocent, family-oriented concept on its ear, with characters that are sketchy, untrustworthy or a little bit repulsive.

But it's sort of awe-inspiring to see a velociraptor pack attack an ice cream truck with thrilling, kinetic immediacy, followed by a shot of one critter running around wearing the driver's red and white striped hat.