Spinosaurus is a huge semi-aquatic dinosaur from the Cretaceous, that lived 99 to 93.5 million years ago. It was the largest of all known terrestrial carnivores. It had paddle-like feet and nostrils on top of its crocodile-like head. This would let it submerge, similar to a crocodile. Some research suggest it was larger than Tyrannosaurus rex, but more clumsy on land, moving as a quadruped.