Picture this epic showdown between Spinosaurus and Purussaurus, right? Spinosaurus, this hulking dinosaur with that iconic sail on its back, was a real water lover, cruising around ancient rivers and ...

exploring the evolutionary features that set them apart from other dinosaurs. In This Article Spinosaurus, distinguished by ...

One member of this group was a large, sail-backed animal called dimetrodon, which looks like it could be a dinosaur but isn’t. Then 252 million years ago came the Permian-Triassic extinction event.