Spinosaurus is a genus of theropod dinosaur that lived in what now is North Africa, during the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago. This genus was known first from Egyptian remains discovered in 1912 and described by German paleontologist Ernst Stromer in 1915. The original remains were destroyed in World War II, but additional material has come to light in recent years. It is unclear whether one or two species are represented in the fossils reported in the scientific literature. The best known species is S. aegyptiacus from Egypt, although a potential second species, S. maroccanus, has been recovered from Morocco.
Spinosaurus was among the largest of all known carnivorous dinosaurs, …show more content…
Both Friedrich von Huene in 1926 and Donald F. Glut in 1982 listed it as among the most massive theropods in their surveys, at in length and upwards of in weight. In 1988, Gregory Paul also listed it as the longest theropod at, but gave a lower mass estimate of . The Dal Sasso et al. estimates were criticized because the skull length estimate was uncertain, and scaling Suchomimus which was long and in mass to the range of estimated lengths of Spinosaurus would produce an estimated body mass of .
François Therrien and Donald Henderson, in a 2007 paper using scaling based on skull length, challenged previous estimates of the size of Spinosaurus, finding the length too great and the weight too small. Improvement of the precision of size estimates for Spinosaurus requires the discovery of more complete remains as available for some other dinosaurs, especially the limb bones of Spinosaurus which are "hitherto unknown". The neural spines were slightly longer front to back at the base than higher up, and were unlike the thin rods seen in the pelycosaur finbacks Edaphosaurus and Dimetrodon, contrasting also with the thicker spines in the iguanodontian Ouranosaurus.
The following cladogram shows an analysis of Tetanurae simplified to show only Spinosauridae from Allain et al. :
Discovery and …show more content…
maroccanus was originally described by Dale Russell in 1996 as a new species based on the length of its neck vertebrae. most researchers regard S. maroccanus as a nomen dubium or as a junior synonym of S. aegyptiacus. Described by Taquet and Russell in 1998, the specimen is in width; no length was stated. The body proportions of this specimen have been debated as the hind limbs are disproportionately shorter in the specimen than in previous reconstructions. However, it has been demonstrated by multiple paleontologists that the specimen is not a chimaera, and is indeed a specimen of Spinosaurus that suggests that the animal had much smaller hind limbs than previously