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Spinosaurus aegyptiacus ("Egyptian spine lizard") is a theropod dinosaur species from the Albian to early Cenomanian stages of the Cretaceous period, about 95 to 93 million years ago. Its distinctions include being the biggest meat-eating of all dinosaurs, rivaling even Tyrannosaurus rex (at somewhere between 12 to 20 metres (40 and 60 feet) long, 4.8 to 6 metres (16 to 20 feet) tall, and 4.5 to 6 tons, having large bones extending from the vertebrae up to 1.8 m long. These spines most likely had skin or a membrane stretching between them, forming a sail-like structure. Spinosaurus provides the name of a family of dinosaurs, the Spinosauridae, of which other members include Angaturama (probably synonymous with Irritator), Baryonyx, Irritator, Suchomimus, and Siamosaurus.

Much mystery surrounds the nature of this animal. First of all, although it has been well-known to dinosaur enthusiasts because of its unusual features, even before it was popularized by its role as main antagonist in Jurassic Park III, it is mostly known through remains that have been destroyed, aside from a few more recently discovered teeth. Unpublished jaw and skull material suggest that it may have had one of the longest skulls of any carnivorous dinosaur. Originally found in the Baharija Valley of Egypt in 1912, it was named by German paleontologist Ernst Stromer in 1915. Some of the fossils were damaged during transport back to the Munich Museum in Germany, and the remaining bones were completely lost due to Allied bombing in 1944.

Aside from its sail, notable characteristics of Spinosaurus include:

• A long, narrow snout similar to other Spinosaurids, and like them filled with conical teeth.
• A slender build.
• One enlarged, hook-like claw on each of its front limbs, perhaps for catching fish.
• Relatively short legs and long arms, leading some paleontologists to suggest it may have been quadrupedal, rather than strictly bipedal (though it was undoubtedly capable of at least facultative bipedality).

Much of this is speculation based on Baryonyx and other Spinosaurids, as no limb material has ever been attributed to Spinosaurus.

Scientists disagree whether Spinosaurus was a cursorial predator (like Tyrannosaurus rex) or a docile fisher, sitting lazily by riverbanks and snatching up helpless prey as they swam by. In Jurassic Park III, it is portrayed as a lethal and dangerous killer, even winning a battle with a Tyrannosaurus. However as noted above, despite its length, it was more lightly built than Tyrannosaurus and other theropods, and its elongated jaws and conical teeth suggest it may have largely eaten fish, or else fed on carrion, rather than being a hunter of large prey like Tyrannosaurus.

Also, the purpose of its sail is unclear. Scientists have suggested it could have been used to regulate temperature, or to attract mates, or to intimidate rivals. However, the use of such an odd structure can probably only be based on speculation. The fact that other dinosaurs of the same time and area, namely the ornithopod Ouranosaurus and the sauropod Rebbachisaurus, possessed a similar structure is interesting. The sail is possible analogous (not homologous) to that of the Permian mammal-like reptile, Dimetrodon, who lived before the dinosaurs even appeared, strongly points in the direction of parallel evolution.

It is very possible that the sail was very vascular and used by the animal to heat itself up when sunrise took place, by turning the sail at a 90 degree angle to the rising sun. This would imply that the animal was only partly warm-blooded at best and lived in climates where nighttime temperatures were cool or low and the sky usually not cloudy. It is thought that Spinosaurus and Ouranosaurus both lived in or at the margins of an earlier version of the Sahara Desert, which would explain this.

External links

• "Spinosaurus". DinoData.

• Dinosaurs
• Jurassic Park species