Streptospondylus (meaning "reversed vertebra") is a genus of tetanurantheropoddinosaur known from the Late Jurassic period of France, 161million years ago. It was a medium-sized predator with an estimated length of 6 meters (19.5ft) and a weight of 500kg (1,100lbs).[2]
Discovery and naming
Restoration in its habitat
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.[1]
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.[3][4] 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".[3] Louis-Benoît Guersent (1777–1848), professor of natural history in this school, drew the attention of Georges Cuvier to these 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.[5]
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.[6] 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.[7]
In 1832 however, the German paleontologistChristian 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.[8] 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.
Type specimen of S. cuvieri
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.[9] 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 2001, Ronan Allain concluded that no connection could be proven between Piveteausaurus and the referred other theropod material from Normandy. He also pointed out that the skull von Meyer had based Streptospondylus altdorfensis on was in fact a composite of bones from two species, since named Steneosaurus edwardsi Deslongchamps 1866 and Metriorynchus superciliosum Blainville 1853 (Steel 1973). A lectotype had never been chosen from one of the composite parts to give the name Streptospondylus priority over either one of these species. Allain used this situation to remove all the crocodilian material from the Streptospondylus type by designating the complete (postcranial) theropod material as the lectotype. As Steneosaurus rostromajor had been based on the composite skull, the epithet rostromajor now no longer had priority over altdorfensis. This way in 2001 Streptospondylus altdorfensis became the valid name and type species of a theropod. Laelaps gallicus and Megalosaurus cuvieri are its objective junior synonyms.[1]
The lectotype specimens, MNHN 8605-09, 8787-89, 8793-94, 8907, were probably found at the coast in layers of the Falaises des Vaches Noires near Calvados, dating from the late Callovian or early Oxfordian, about 161 million years old. They consist of several vertebrae series, single vertebrae, a partial left pubis and limb elements. The longest vertebra has a length of 97 millimetres, indicating a total body length of about seven metres. Also a partial left femur, MNHN 9645, has been referred. Streptospondylus has been diagnosed by the unique bifurcation (split) of the hypapophyses (processes which extend from the lower surface of a vertebra) in the anterior dorsal vertebrae.[11]
Material referred to S. major by Owen
Owen also named two other species, S. major[9] (S. recentior is a museum label for syntype specimens [12]) and S. meyeri,[13] of which the former is based on iguanodont material. His S. cuvieri, of which the type specimen is lost, is today considered a nomen dubium.
In 2022, theropod specimens from the same locality as the type of Streptospondylus, long held in private collections, were described. It was found that some dorsal vertebrae (MNHN.F.RJN472;B5) bore autapomorphies of Streptospondylus, while a cervical vertebra (MPV 2020.1.11), a tibia (MPV 2020.1.2) and a femur were referred to the species, based on shared characters with the related genus Eustreptospondylus.[14]
Phylogeny
Earlier assigned to crocodilian groups, Streptospondylus was in the 20th century typically classified in the Megalosauridae.
Recent analyses indicate that Streptospondylus is a tetanurantheropod. Allain in 2001 suggested that it was closely related to Eustreptospondylus in the Spinosauroidea. Roger Benson in 2008 and 2010 concluded that whether it is a megalosauroid, allosauroid, or a more primitive form cannot be determined because of its extremely fragmentary remains.[15] Later cladistic analysis by Benson and colleagues from 2010 indicated that Streptospondylus was the sister species of Magnosaurus within the Megalosauridae.[16] Carrano et al. (2012) placed Streptospondylus at Megalosauriaincertae sedis due to its fragmentary nature.[17]
Megalosaurus is an extinct genus of large carnivorous theropod dinosaurs of the Middle Jurassic Epoch of southern England. Although fossils from other areas have been assigned to the genus, the only certain remains of Megalosaurus come from Oxfordshire and date to the late Middle Jurassic.
Neovenator is a genus of carcharodontosaurian theropod dinosaur. It is known from several skeletons found in the Early Cretaceous (Hauterivian-Barremian) Wessex Formation on the south coast of the Isle of Wight, southern England. It is one of the best known theropod dinosaurs from the Early Cretaceous of Europe.
Afrovenator is a genus of megalosaurid theropod dinosaur from the Middle or Late Jurassic Period on the Tiourarén Formation and maybe the Irhazer II Formation of the Niger Sahara region in northern Africa. Afrovenator represents the only properly identified Gondwanan megalosaur, with proposed material of the group present in the Late Jurassic on Tacuarembó Formation of Uruguay and the Tendaguru Formation of Tanzania.
Metriacanthosaurus is a genus of metriacanthosaurid dinosaur from the upper Oxford Clay of England, dating to the Late Jurassic period, about 160 million years ago.
Altispinax is a genus of large predatory theropod dinosaur from the Early Cretaceous period of what is now the Wadhurst Clay Formation of East Sussex, England.
Eustreptospondylus is a genus of megalosaurid theropod dinosaur, from the Oxfordian stage of the Late Jurassic period in southern England, at a time when Europe was a series of scattered islands.
Megalosauridae is a monophyletic family of carnivorous theropod dinosaurs within the group Megalosauroidea. Appearing in the Middle Jurassic, megalosaurids were among the first major radiation of large theropod dinosaurs. They were a relatively primitive group of basal tetanurans containing two main subfamilies, Megalosaurinae and Afrovenatorinae, along with the basal genus Eustreptospondylus, an unresolved taxon which differs from both subfamilies.
Megalosauroidea is a superfamily of tetanuran theropod dinosaurs that lived from the Middle Jurassic to the Late Cretaceous period. The group is defined as Megalosaurus bucklandii and all taxa sharing a more recent common ancestor with it than with Allosaurus fragilis or Passer domesticus. Members of the group include Spinosaurus, Megalosaurus, and Torvosaurus. They are possibly paraphyletic in nature with respect to Allosauroidea.
Chuandongocoelurus is a genus of carnivorous tetanuran theropod dinosaur from the Jurassic of China.
Cristatusaurus is a genus of theropod dinosaur that lived during the Early Cretaceous Period of what is now Niger, 112 million years ago. It was a baryonychine member of the Spinosauridae, a group of large bipedal carnivores with well-built forelimbs and elongated, crocodile-like skulls. The type species Cristatusaurus lapparenti was named in 1998 by scientists Philippe Taquet and Dale Russell, on the basis of jaw bones and some vertebrae. Two claw fossils were also later assigned to Cristatusaurus. The animal's generic name, which means "crested reptile", alludes to a sagittal crest on top of its snout; while the specific name is in honor of the French paleontologist Albert-Félix de Lapparent. Cristatusaurus is known from the Albian to Aptian Elrhaz Formation, where it would have coexisted with sauropod and iguanodontian dinosaurs, other theropods, and various crocodylomorphs.
Metriacanthosauridae is an extinct family of allosauroid theropod dinosaurs that lived from the Middle Jurassic to the Early Cretaceous. When broken down into its Greek roots, it means "moderately-spined lizards". The family is split into two subgroups: Metriacanthosaurinae, which includes dinosaurs closely related to Metriacanthosaurus, and another group composed of the close relatives of Yangchuanosaurus. Metriacanthosaurids are considered carnosaurs, belonging to the Allosauroidea superfamily. The group includes species of large range in body size. Of their physical traits, most notable are their neural spines. The records of the group are mostly confined to Asia, though Metriacanthosaurus is known from Europe. Metriacanthosauridae is used as a senior synonym of Sinraptoridae.
Dubreuillosaurus is a genus of carnivorous dinosaur from the middle Jurassic Period. It is a megalosaurid theropod. Its fossils were found in France. The only named species, Dubreuillosaurus valesdunensis, was originally described as a species of Poekilopleuron, Poekilopleuron? valesdunensis, which is still formally the type species of the genus. It was later renamed Dubreuillosaurus valesdunensis when, in 2005, Allain came to the conclusion that it was not part of the genus Poekilopleuron. Its type specimen, MNHN 1998-13, is only rivalled in the number of preserved elements in this group by that of Eustreptospondylus. Dubreuillosaurus is considered to be the sister species of Magnosaurus. It did not show signs of insular dwarfism even though it was uncovered on an island.
Erectopus is an extinct genus of basal allosauroid theropod from the Early Cretaceous La Penthiève Beds Formation of France and also possibly the Cernavodă Formation of southern Romania. The type species is E. superbus, which was initially known as a species of Megalosaurus.
Marshosaurus is a genus of medium-sized carnivorous theropod dinosaur, belonging to the family Piatnitzkysauridae, from the Late Jurassic Morrison Formation of Utah and possibly Colorado.
Piveteausaurus is a genus of theropod dinosaur known from a partial skull discovered in the Middle Jurassic Marnes de Dives formation of Calvados, in northern France and lived about 164.7-161.2 million years ago. In 2012 Thomas Holtz gave a possible length of 11 meters.
Spinostropheus is a genus of carnivorous neotheropod theropod dinosaur that lived in the Middle Jurassic period and has been found in the Tiouraren Formation, Niger. The type and only species is S. gautieri.
Poekilopleuron is a genus of tetanuran dinosaur, which lived during the middle Bathonian of the Jurassic, about 168 to 166 million years ago. The genus has been used under many different spelling variants, although only one, Poekilopleuron, is valid. The type species is P. bucklandii, named after William Buckland, and many junior synonyms of it have also been erected. Little material is currently known, as the holotype was destroyed in World War II, although many casts of the material still exist.
Suchosaurus is a spinosaurid dinosaur from Cretaceous England and Portugal, originally believed to be a genus of crocodile. The type material, consisting of teeth, was used by British palaeontologist Richard Owen to name the species S. cultridens in 1841. Later in 1897, French palaeontologist Henri-Émile Sauvage named a second species, S. girardi, based on two fragments from the mandible and one tooth discovered in Portugal. Suchosaurus is possibly a senior synonym of the contemporary spinosaurid Baryonyx, but is usually considered a dubious name due to the paucity of its remains, and is considered an indeterminate baryonychine. In the Wadhurst Clay Formation of what is now southern England, Suchosaurus lived alongside other dinosaurs, as well as plesiosaurs, mammals, and crocodyliforms.
Duriavenator is a genus of theropod dinosaur that lived in what is now England during the Middle Jurassic, about 168 million years ago. In 1882, upper and lower jaw bones of a dinosaur were collected near Sherborne in Dorset, and Richard Owen considered the fossils to belong to the species Megalosaurus bucklandii, the first named non-bird dinosaur. By 1964, the specimen was recognised as belonging to a different species, and in 1974 it was described as a new species of Megalosaurus, M. hesperis; the specific name means 'the West' or 'western'. Later researchers questioned whether the species belonged to Megalosaurus, in which many fragmentary theropods from around the world had historically been placed. After examining the taxonomic issues surrounding Megalosaurus, Roger B. J. Benson moved M. hesperis to its own genus in 2008, Duriavenator; this name means "Dorset hunter".
The Marnes de Dives is a geological formation in Normandy, France. It dates back to the upper part of the Callovian stage of the Middle Jurassic. And is partially equivalent to the Oxford Clay in England. It predominantly consists of ooidal marl, rich in pyrite and lignite, interbedded with thin limestone horizons. It is best exposed at the base of the Falaises des Vaches Noires as well as the foreshore at low tide. It is known for its fossils, notably those of ammonites, marine crocodiles and fragmentary remains of dinosaurs, mostly theropods.
References
1 2 3 Allain R (2001). "Redescription de Streptospondylus altdorfensis, le dinosaure théropode de Cuvier, du Jurassique de Normandie [Redescription of Streptospondylus altdorfensis, Cuvier's theropod dinosaur from the Jurassic of Normandy]". Geodiversitas. 23 (3): 349–367.
1 2 Paul, G.S. 2010. The Princeton Field Guide to Dinosaurs. Princeton University Press, 89 pp
1 2 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 Palevol15: 595–605 (in French with an abridged English version).
↑ Brignon, A. (2016) Le premier "chasseur de dinosaures" en France: l'abbé Charles Bacheley (1716-1795). Fossiles: Revue française de Paléontologie27: 36-42.
↑ Cuvier G (1800). "Sur une nouvelle espèce de crocodile fossile". Bulletin des Sciences, Société Philomathique de Paris. 2: 159.
↑ Cuvier G (1808). "Sur les ossements fossiles de crocodiles et particulièrement sur ceux des environs du Havre et d'Honfleur, avec des remarques sur les squelettes de sauriens de la Thuringe". Annales du Muséum d'Histoire naturelle de Paris. XII: 73–110.
↑ Geoffroy Saint-Hilaire E (1825). "Recherches sur l'organisation des gavials". Mémoires du Muséum national d'Histoire naturelle. 12: 97–155.
↑ Meyer, H. von, (1832), Paleologica zur Geschichte der Erde, Frankfurt am Main, 560 p
1 2 Owen R (1842). "Report on British fossil reptiles". Report of the British Association for the Advancement of Science. 11: 60–204.
↑ Walker A.D. (1964). "Triassic reptiles from the Elgin area: Ornithosuchus and the origin of carnosarus". Philosophical Transactions of the Royal Society of London. 248 (744): 53–134. Bibcode:1964RSPTB.248...53W. doi:10.1098/rstb.1964.0009.
↑ Carrano, Matthew T.; Benson, Roger B. J.; Sampson, Scott D. (2012-05-17). "The phylogeny of Tetanurae (Dinosauria: Theropoda)". Journal of Systematic Palaeontology. 10 (2): 211–300. doi:10.1080/14772019.2011.630927. ISSN1477-2019. S2CID85354215.
↑ Mantell, G. A., 1851, Petrifactions and their teachings; or a hand-book to the Gallery of Organic remains of The British Museum, London, 496pp.
↑ Owen, R., 1854a. Descriptive catalogue of the fossil organic remains of reptilia and pisces contained in the Museum of The Royal College of Surgeons of England: 184pp.
↑ M. T. Carrano, R. B. J. Benson, and S. D. Sampson. 2012. The phylogeny of Tetanurae (Dinosauria: Theropoda). Journal of Systematic Palaeontology 10(2):211-300
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