The Land That Time Forgot
1975

Oh dear. The Effects That Time Has Not Been Kind To might be a better title these days - Jurassic Park this most surely is not. It's not even Valley Of Gwangi (and that was made before it). But despite not being a horror film at all, it was made by Amicus - so I suppose I might as well mention it.
And to give it its wobbly rubbery due, the scenes before we actually reach the Land of the title are actually quite good, reasonably gripping and positively entertaining. Because they're straight-out wartime derring-do, and there's NOT a shit monster to be seen.
Doug McClure, professional roll-necked jumper wearer you might remember from such films as... erm... this one, finds himself cast adrift with Susan Penhaligan after their boat is torpedoed by a U-boat.
Before you can say "Achtung! Ze Americaner swinehund has gertaken uber das boot!" Old Doug has rallied together his bunch of sweaty sailors and kicked the shit out of the hun. Hurrah!
Unfortunately, the Hun soon rally their forces and it's Cabbage Crunchers...2 Doug McClure's All Star Panto Regulars... 1. But not for long, and soon Doug's back in charge. Luckily, he's also an expert in U-Boat design (like most American civilians during WW2, I think you'll agree) and decides to pilot it himself. Unluckily, he gets lost and they end up at the South Pole.
It's about at this point that the audience suddenly remembers why they wanted to watch the film in the first place (ie monsters), but they don't have long to wait. The friendly German U-boat commander reckons he knows where they are and they sail under an ice flo, coming up in a Tropical paradise. From then on it's a non-stop battle against both huge, dodgy-looking dinosaurs which the cast have to grab hold of in an attempt to make them look like they're attacking, and tribes of Stone Age people, explained away by the land being full of animals from all periods of time (apparently).
As McClure fights gamely on with Penhaligon at his side, the rest of the cast (including evil Anthony Ainley and chubby Keith Baron) gradually get whittled down by the unconvincing foe. There's a sequel (The People That Time Forgot - great, not even any monsters), and if you're very clever you can just watch the first 10 minutes of that to get a handy precis of the dire original, then turn it off. That's what I did.

Land That Time Forgot (1975)
Director: Kevin Connor Writer(s): Edgar Rice Burroughs (novel) James Cawthorn Michael Moorcock
Cast: Doug McClure - Bowen Tyler, John McEnery - Captain Von Schoenvorts, Susan Penhaligon - Lisa Clayton, Keith Barron - Bradley, Anthony Ainley - Dietz, Godfrey James - Borg, Bobby Parr - Ahm, Declan Mulholland - Olson, Colin Farrell - Whiteley, Ben Howard - Benson, Roy Holder - Plesser, Andrew McCulloch - Sinclair, Ron Pember - Jones, Grahame Mallard - Deusett, Andrew Lodge - Reuther, Brian Hall - Schwartz, Stanley McGeagh - Hiller, Peter Sproule - Hindle, Steve James - First Sto-Lu