Ray Harryhausen's Allosaurus in the film One Million Years BC is one of the most reconizible dinosaurs from the film. The allosaurus with incredible detailed skin, covered in scales, bumps, ridges, and reptile like patterns around the mouth and eyes, was one of the most notatable dinosaurs from the film, along with the pterandon.
The allosaurus has a unique skin pigment from brownish, purplish, to even greenish at times, with incredibly detailed skin, ridges arounds its mouth and eyes, similar to geckos or iguanas, and reptile-like scales and bumps covering its body. The allosaurus stood some where ten to 24 feet tall upwright with its tail dragging on the ground (however it wasn't in this position for the whole movie) like a T-Rex.
The allosaurus was similar to Gwangi in the aspect of an agressive apex predator, but the allosaurus wasn't, because their were other main predators in the area (Ceratasaurus, Pteranodon, Giant Iguana). However that didn't stop him from being agressive like Gwangi. The allosaurus was very agressive, however tented to feed on small easy prey, like humans. In the film the allosaurus attacked The Shell Tribe. The allosaurus prefered to eat the young (in the film he tried to eat children in a tree) but wouldn't mind eating adult cavemen either. The allosaurus was very agressive, and wasn't afraid of any human attack, making him very hard to kill. However, Tumak, a caveman, did kill the beasts, however it took many tries and a pole to finnaly killed the allosaurus.