Spinosaurus is a large Spinosaurid dinosaur that lived 99-93 million years ago during the Cenomonian stage of the upper Cretaceous period in what is now known as North Africa. First remains of spinosaurus was described by the German paleontologist Ernst Stromer in 1912. Even for the time Stromer realized that this animal was a bizzare animal , different from any other theropod dinosaur known at the time with even the potential of being larger than the recently discovered Tyrannosaurus. The best known species of Spinosaurus is S. aegyptiacus but there is also another species spinosaurus named S. morracanus (although S. morracanus might just be the same animal as S. aegyptiacus. so it currently is a dubious species) There also used to be the debate about Sigilmassasaurus brevicolis which has now been synonymized with Spinosaurus aegyptiacus. Another possible synonym is another large Spinosaurid dinosaur known as Oxalaia quilombensis from Brazil , but this is still heavily debated.
Spinosaurus is the largest of all terrestrial carnivores. Estimates published between 2005-2008 put the animal in a length between 13-18 meters and 7-20 tonnes but the current estimates for the animal puts it in a size range between 14-16 meters and 5-7 tonnes.The skull of Spinosaurus was long, low and narrow, similar to that of a modern crocodilian, and bore straight conical teeth with no serrations. It would have had large, robust forelimbs bearing three-fingered hands, with an enlarged claw on the first digit. The distinctive neural spines of Spinosaurus, which were long extensions of the vertebrae (or backbones), grew to at least 1.65 meters long and were likely to have had skin connecting them, forming a sail-like structure, although some authors have suggested that the spines were covered in fat and formed a hump. Spinosaurus's hip bones were reduced, and the legs were very short in proportion to the body. Its long and narrow tail was deepened by tall, thin neural spines and elongated chevrons, forming a flexible fin or paddle-like structure.
Spinosaurus is known to have eaten fish, and most scientists believe that it hunted both terrestrial and aquatic prey. Evidence suggests that it was highly semiaquatic, and lived both on land and in water much like modern crocodilians do. Spinosaurus's leg bones had osteosclerosis (high bone density), allowing for better buoyancy control, and the paddle-like tail was likely used for underwater propulsion. Multiple functions have been put forward for the dorsal sail, including thermoregulation and display; either to intimidate rivals or attract mates. Spinosaurus lived in a humid environment of tidal flats and mangrove forests alongside many other dinosaurs, as well as fish, crocodylomorphs, lizards, turtles, pterosaurs, and plesiosaurs.