Of all the John Dark/Kevin Connor/Doug McLure adventure fantasies of the Seventies, I think At The Earth's Core is my favorite. Mostly because of the presence of Caroline Munro, I admit, although I'm also grateful for Peter Cushing's inclusion in the cast.
I also enjoy the bizarro man-in-suit creatures created by the filmmakers to stand-in for the prehistoric beasties of Edgar Rice Burroughs' original novel. Their fanciful designs frankly delight me. I can only assume that the producer/director team of Dark and Connor chose not to use dinosaurs in Core order to differentiate this flick from their Time Forgot films.