In a mere three minutes this movie has more life and fun and personality than either of the two needless remakes. Just three minutes of footage- and not all of it's stop-motion animation. One can easily see why the late Ray Harryhausen was so taken with this movie just by this fight scene alone.
And despite what some fans think, this was a t rex. At the time the movie was made they weren't sure how many fingers the rex was supposed to have on it's tiny little arms. It's fashionable now to some people to call it an allosaurus, but all the books that talked to the people involved say it was a rex. Even Gwangi is supposed to be a rex.