Streptospondylus Altdorfensis

''Streptospondylus'' (meaning "reversed vertebra") is a genus of tetanuran theropod dinosaur known from the Late Jurassic period of France, 161 million years ago. It was a medium-sized predator with an estimated length of 6 meters (19.5 ft) and a weight of 500 kg (1,100 lbs).

Discovery and naming

''Streptospondylus'' was one of the first dinosaurs collected and was the first described, though not the first dinosaur named. It was not recognised as a theropod dinosaur until 2001.

In 1778, abbey Charles Bacheley, a Norman naturalist, reported the presence of fossil bones in the Callovo-Oxfordian formations, either the Marnes de Dives or the overlying Marnes de Villers, probably the former, exposed at the foot of the Vaches Noires cliffs between Villers-sur-Mer and Houlgate.Brignon, A. (2016) Abbé Bacheley and the discovery of the first dinosaurs and marine crocodilians from the Jurassic of the Vaches Noires (Callovian/Oxfordian, Normandy, France). ''Comptes Rendus Palevol'' 15 : 595–605 (in French with an abridged English version). These fossil materials contained theropod vertebrae and marine crocodilian remains. After the death of Bacheley, his fossil cabinet was acquired by the "Ecole centrale de Rouen". Louis-Benoît Guersent (1777–1848), professor of natural history in this school, drew the attention of Georges Cuvier to this remarkable fossil bones. With the agreement of the prefect of Seine-Inférieure, count Jacques Claude Beugnot, Guersent sent the collection to the Muséum National d'Histoire Naturelle in Paris. In 1800, these fossils were briefly mentioned by Georges Cuvier who misspelled the name of their former owner as Bachelet.

In 1808, Cuvier scientifically described the theropod vertebrae as the first dinosaur remains ever. However, he considered them to be crocodilian and associated them with fossils of the Teleosauridae and the Metriorhynchidae. In 1822, Cuvier by the work of Henry De La Bèche became aware that these finds were very disparate, stemming from different periods. He abstained from naming them but in 1824 concluded that there were two main types. In 1825 Étienne Geoffroy Saint-Hilaire accordingly named two crocodilian skulls as the genus ''Steneosaurus'', the one, specimen MNHN 8900, becoming ''Steneosaurus rostromajor'', the other, MNHN 8902, ''S. rostrominor''.

In 1832 however, the German paleontologist Christian Erich Hermann von Meyer split the material. ''Steneosaurus rostrominor'' was renamed ''Metriorhynchus geoffroyii'' while ''Steneosaurus rostromajor'' became ''Streptospondylus altdorfensis''. To the last species the theropod remains were referred. The generic name is derived from Greek ''στρεπτος''/''streptos'', "reversed", and ''σπονδυλος''/''spondylos'', "vertebra", alluding to the fact that the vertebrae differed from typical crocodile elements in being opisthocoel: convex in front and concave behind. The specific name refers to Altdorf where some teleosaurid remains had also been found. Von Meyer's name was the first binomial name (also) referring to a theropod.

In 1842 Richard Owen pointed out that von Meyer had been incorrect in changing the original specific name and created the correct combination ''Streptospondylus rostromajor'' for ''Streptospondylus altdorfensis''. At the same time he created a second species: ''Streptospondylus cuvieri'' based on a single damaged vertebra from the Bajocian, found near Chipping Norton. In 1861, Owen would refer the entire Cuvier material to ''S. cuvieri'', despite the fact that if it were cospecific the name ''S. rostromajor'' would have priority. From that time ''S. cuvieri'' was generally accepted in the literature as the valid name, though some workers split off the theropod remains from the crocodilian bones, Edward Drinker Cope in 1867 naming a ''Laelaps gallicus'' and Friedrich von Huene in 1909 a ''Megalosaurus cuvieri''.

In 1964, Alick Donald Walker discovered Owen's mistake, referring the entire theropod material to the new species '' Eustreptospondylus divesensis'' which, however, had a skull not belonging to the Cuvier material as the type specimen, MNHN 1920–7. In 1977 Philippe Taquet created the genus ''Piveteausaurus'' for this species.

In 2001, Ronan Allain