Spinosaurus (meaning "spine lizard") is a genus of theropod dinosaur which lives in the Rainy Basin.
The distinctive spines of Spinosaurus, which are long extensions of the vertebrae, grew up to 6 feet long and have skin connecting them, forming a sail-like structure.
The Spinosaurus skull has a narrow snout filled with straight conical teeth that lack serrations. There are six or seven teeth on each side of the very front of the upper jaw, in the premaxilla bones, and another twelve in both maxillae behind them. The second and third teeth on each side are noticeably larger than the rest of the teeth in the premaxilla, creating a space between them and the large teeth in the anterior maxilla; large teeth in the lower jaw faced this space. The very tip of the snout holding those few large anterior teeth was expanded, and a small crest was present in front of the eyes.
The sail of Spinosaurus is formed of very tall neural spines growing on the back vertebrae. These spines are seven to eleven times the height of the vertebrae from which they grow. The spines were slightly longer front to back at the base than higher up, and are unlike the thin rods seen in the pelycosaur finbacks Edaphosaurus.
It was a 52 feet long predator.