The time is…sometime in the past, the place is Mexico, and the thing, that is … Gwangi! He is a terrifying t-rex like beast! You’ll find him, along with a bunch of other made up extinct things secreted in a ‘forbidden valley’ that is either one, or many many perilous days ride from the new town – it is not really made clear where the forbidden valley is, but it takes either very little time to get there, or ages.
Its kind of a tale of two halves, the part before Gwangi shows up, where all sorts of silly stuff goes on with a tiny horse, some questionable sexy scenes and lots of fannying around on horses. Then there is the second, possibly more enjoyable part where Gwangi is doing his thing, roaring and battling other dinosaur type things and generally being badass.
We don’t actually get to the eponymous valley until well into the movie. Mouth chomp! The effects are exactly what you’d expect from a sixties monster pic, sort of plasticine looking and not particularly good. Dino Bite! What is done well though is the interaction between the humans and the creatures, something which is difficult to get right even now with all this cgi, they pull off with aplomb. Foot crush!
Anyway, write off the awful racial stereotypes and get into this classic load of rubbish, you’ll probably not regret it, and even if you do its going to be fun to tell everyone how good the plastic dinosaurs are.