The movie I'm looking for was a sci fi.. it involved a group of scientists w/ an EARTH DRILLING MACHINE that took them to a lost world of dinosouars etc. I don't remember any other humans being where they ended up.. (no Natives) but them.. at the end the older \elder scientist stayed behind to continue to battle the T- REX that tormented them the whole time they were there.. at first arrival the drilling machine landed in water where they had to deal with leeches in the water that they landed in. The Name of the movie is not "The lost World" with the German sub and all! It was later than that... I THINK. Please help! OH for reference.. in one sceen they had built a catapult to heave a huge rock at the T-REX..

Sounds like The Last Dinosaur, but there are prehistoric humans in it. Here's a link with some pictures: The Last Dinosaur