Spinosaurus (pronounced SPINE-no-SAWR-us) was a meat-eating dinosaur that lived during the middle Cretaceous period about 95 million years ago. Spinosaurus (meaning "spiny lizard") is called that because it had a series of large neural spines up to 6 feet (1.8 m) long coming out of its back vertebrae, probably forming a sail-like fin that may have helped in thermoregulation, mating rituals and/or intraspecies rivalry.
Anatomy: Spinosaurus was bipedal (it walked on two legs). It was about 40-50 feet long (12-15 m) and weighed 4 tons or more; it is the largest known Spinosaurid (a type of meat-eating dinosaur). It had a large head with sharp, straight, non-serrated teeth in a powerful, crocodile-like lower jaw.
The Sail: Spinosaurus' huge sail may have been used for regulating its temperature. It could collect warmth from the sun and also disperse excess body heat when in the shade. The presence of this sail as a thermo-regulatory device is evidence that Spinosaurus may have been a cold-blooded animal. The sail may also have been used for mating rituals, attracting mates. The sail may have been brightly colored, like the fins of some modern-day reptiles.
Diet: Segnosaurus was a carnivore (meat-eater) with huge teeth and powerful jaws; it ate animals, including smaller dinosaurs.