After a very rocky start, where this seems to have aspirations no higher than a tired sit-com, this kicks into gear when Manny (Romano) and his mammoth wife (Latifah) find themselves in a 'lost world' populated by prehistoric monsters. They are there in search of Sid (Leguizamo), who was swept away after his attempts to be a foster parent to some eggs went badly awry: their real mother, a T-Rex, shows up. And it turns out that even she is not the top of the dinosaur food-chain, since there's "Rudy", a massive carnivore whose mere roar is enough to send Mama Tyrannosaurus scurrying for cover. Thankfully, Manny and Co are helped by a crazy weasel called Buck (Pegg), who has the street-smarts to survive in this jungle where danger lurks round every corner, but is unquestionably a couple of sandwiches short of a picnic.
Even before we knew it was Pegg giving voice to the character, Buck had proved the film's major saving grace (along with the always reliable saber-tooth squirrel Scratt, who steals his scenes with effortless ease). The dynamic between the three leads which powered the original film is all but gone, since they get about two scenes together, and it's a shame to see Sid and sabertooth Diego reduced to minor sipport. But once he shows up, Buck's loopy insanity is a credible replacement, with lines like "Let me tell you about the time I turned a Tyrannosaurus Rex into Tyrannosaurus Rachel." The film was originally made in 3D, and that probably explains the hyperkinetic style, with a lot of chase scenes and camera motion - these aspects are handled with some energy, and help overcome generally-limited animation [no-one will mistake this for Pixar]. If nothing in the plot will qualify as even a mild surprise, this wasn't the disaster it was shaping up to be in the first 20 minutes. But someone had better push Latifah into a tar-pit before the fourth installment.