I saw this movie when I was a kid and have tried to track it down several times, but never was able to figure out the title.
From what I remember, the movie has a male and female main characters and broadly followed a "Journey to the Center of the Earth" plot. The characters were part of a military operation and at some point find themselves in a hidden land filled with dinosaurs. I clearly remember a few scenes.
- A large-scale bombardment of the land when the dinosaurs are discovered. I think that there is a bit where the top of a triceratops's head plate is blown off by one of the mortars.
- One of the military people remarks that they need to keep moving further North to find food.
- The movie ends with the two main characters walking together in a snow storm wearing fur outfits (presumably representing that they are in the Ice Age era). The male character's voice narrates that they have to keep moving, "North. Always North".