Dismissed as a loon, paleontologist Rick Marshall (Will Ferrell) retreats into junk food and ends up teaching bored kids about the wonders of space until super-keen Brit student Holly Cantrell (Anna Friel) saves him from a sugar overdose and, after telling him she is his biggest fan, persuades him to give his tachyon time machine just one more try.

After finding the nearest time portal at a cheesy roadside attraction run by Will Stanton (Danny McBride) the trio power up the tachyon and take a wild trip into another dimension – a place that’s full of lost relics from history and is populated by dinosaurs, enormous crabs and ape-like men called Pakunis.

One of these Pakunis called Cha-Ka (Jorma Taccone) helps them out, but it’s not long before a T-Rex is hot in their tails and they meet a strange race of evil Sleestak lizards. Enik is the only good lizard in the bunch, and from his Krypton-like cave he warns the trio that plans are afoot for a major invasion of earth by the razor-toothed Sleetstaks: they’ve got to find the tachyon and go back…

As if you hadn’t already guessed, this was originally a very psychedelic 1970’s US kids TV series known for its wobbly sets and far out stories (Holly was originally Rick’s daughter, too). This film, however, seems to be aimed at an adult audience, and this change of tone adds to the feeling that this is perhaps too dated to really work.

Having Rick, Will and Cha-Ka get stoned and talk nonsense to each other seems wildly out of place when you’re thinking: “If this is a fantasy world lost in time, I want to be dazzled by it – not bored.” It’s Holly who seems to do all the clever thinking anyway, and although Farrell tries hard, his character’s brain seems to be out to lunch.

McBride (a rising star from recent movies such as Pineapple Express and Tropic Thunder) has nothing to do either, and that doesn’t bode well for a film that seems to promise comedy. There are only a few funny moments, and although Ferrell’s dancing/singing through a pterodactyl nest is a highlight – as is the Chorus Line reference - it again it shows that when he’s not doing balls-out comedy like Talladega Nights or Blades of Glory, he’s no great shakes.