The People That Time Forgot, sequel to The Land That Time Forgot, is a 1977 science fiction film starring Doug McClure. It is based on the Edgar Rice Burroughs novel with the same name. The book can be read online here, or listen to it here.
Watch it online, with commercials, compliments of hulu.com. [update: no longer available there or anywhere else I've looked.]
This is slow. It looks like they're trying to be dramatic, but the music hitting you over the head isn't the best way to achieve that goal. This one is forgettable. The prehistoric monsters are worse than many I've seen in movies from the 50's. The sexism is also worse than much of what I've seen in 50's movies -much worse really, when you think that this is a 1977! film. We hadn't come a long way, baby, after all.
I see that Princess Leia wasn't alone in her choice of hairstyle.
Moria has a review. 1000 Misspent Hours says it "isn’t anywhere near as good as its best moments suggest it could have been".