Spinosaurus aegyptiacus was a highly unusual theropod dinosaur that lived in Egypt and Morocco around 90 million years ago. It is distinctly different from other carnosaurs in the respect that it has an unusually high vertibrae on it's back that give it a giant fin or sail, about 6 feet high, the purpose of which is not understood. It may have served as a cooling device, for heat dissipation or a sexual signal. Interestingly enough, an iguanodont from the same place at almost the same time, Ouranosaurus, had a similar sail.
The jaws of Spinosaurus are narrow and crocodile-like, and the teeth are straight and not serrated like those of Tyrannosaurus. This feature is very similar to the theropods Baryonyx and Suchomimus, both of which were probable fish-eaters.
Spinosaurus is known only from fragments, the first specimen was
unfortunately destroyed during
World War II. It is estimated that the beast was collosal, perhaps measuring 50 feet in length, but these are only estimates. It seems that although the creature may have been longer than Tyrannosaurus, it had a more slender build.
Pound for pound, both relatively and absolutely,
Tyrannosaurus rex is the more formidable animal, despite what the movie
Jurassic Park 3 depcits. T.rex would be heavier, more powerfully musculed, and have a much stronger bite than Spinosaurus.