Suchosaurus

Suchosaurus
Temporal range: Early Cretaceous
Holotype tooth of S. cultridens
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Clade:Dinosauria
Order:Saurischia
Suborder:Theropoda
Family:†Spinosauridae
Genus:†Suchosaurus
Owen, 1841
Species
  • S. cultridens Owen, 1841 (type)
  • S. girardi Sauvage, 1897
Synonyms

Suchosaurus (meaning "crocodile lizard") is a spinosaurid theropod dinosaur from Cretaceous England, originally believed to be a genus of crocodile. The type material consists of teeth. Two species, S. cultridens and S. girardi have been named.

History of discovery

About 1820, Gideon Mantell acquired teeth discovered near Cuckfield in the Wadhurst Clay of East Sussex, part of a lot with the present inventory number BMNH R36536. In 1822, he reported these, after an identification by William Clift, as belonging to crocodiles.[1] In 1824, the teeth were mentioned and illustrated by Georges Cuvier, representing the first illustration of a spinosaurid fossil (though this group wouldn't be recognized for nearly another century).[2] In 1827 Mantell described additional teeth, pointing out the similarities to the crocodylian Teleosaurus and Gavialis.[3] One of these teeth is the present specimen BMNH R4415, others are part of BMNH R36536.

In 1841, Richard Owen named, based on BMNH R36536 as a syntype series, a subgenus Crocodylus (Suchosaurus) with as type species Crocodylus (Suchosaurus) cultridens.[4] The subgeneric name was derived from Greek σοῦχος, souchos, the name of the Egyptian crocodile god Sobek. This reflected the presumed taxonomic affinities; at the time the crocodile-like snouts of spinosaurids were not known. The specific name is derived from Latin culter, "dagger", and dens, "tooth", in reference to the elongated form of the teeth. In 1842, Owen again mentioned the taxon as a subgenus,[5] subsequently he and other workers would use it as a full genus Suchosaurus. In 1842 and 1878 Owen referred some vertebrae to Suchosaurus,[6] but these likely belong to Ornithischia instead.[7] In 1884, Owen indicated a tooth as "Suchosaurus leavidens" in a caption,[8] this is usually seen as a lapsus calami because this species is not further mentioned.

Type mandible and tooth of S. girardi

In 1897, Henri-Émile Sauvage named a second species: Suchosaurus girardi, based on two jaw fragments (specimen MG324) and a tooth, found in Portugal by Paul Choffat. The specific name honours French geologist Albert Girard.[9] The tooth was considered lost but was rediscovered and in 2013 reported as specimen MNHN/UL.I.F2.176.1, part of remains recovered after a fire in 1978.[10]

During the nineteenth and most of the twentieth century, Suchosaurus was usually considered to have been some obscure crocodilian, perhaps belonging to the Pholidosauridae.[11] Single comparable teeth discovered in England were referred to the genus.[7] However, when publishing a redescription of Baryonyx in 1998, Angela Milner realised that the teeth of that spinosaurid dinosaur were extremely similar to those of Suchosaurus. In 2003, she suggested both genera represented one and the same animal.[12] An identity would imply the name Suchosaurus has priority. However, the Suchosaurus teeth are also indistinguishable from those of Cristatusaurus and Suchomimus, making it an indeterminate baryonychine.

In 2007 Eric Buffetaut considered the teeth of S. girardi very similar to those of Baryonyx (and S. cultridens) except for the stronger development of the crown ribs, suggesting that the remains belonged to the same genus. Buffetaut agreed with Milner that the teeth of S. cultridens were almost identical to those of B. walkeri, but with a ribbier surface. The former taxon might be a senior synonym of the latter (since it was published first), depending on whether the differences were within a taxon or between different ones. According to Buffetaut, since the holotype specimen of S. cultridens is one worn tooth and that of B. walkeri is a skeleton it would be more practical to retain the newer name.[13]

In 2011 Portuguese palaeontologist Octávio Mateus and colleagues agreed that Suchosaurus was closely related to Baryonyx, but considered both species in the former genus (Suchosaurus) nomina dubia (dubious names) since their holotype specimens were not considered diagnostic (lacking distinguishing features) and could not be definitely equated with other taxa.[14]

References

  1. ↑ Mantell, G.A., 1822, The fossils of the South Downs or Illustrations of the Geology of Sussex, London, Rupton Relfe
  2. ↑ Cuvier, G., 1824, Recherches sur les ossemens fossiles, deuxième édition. Dufour & d’Ocagne, Paris. 547 pp
  3. ↑ Mantell, G.A., 1827, Illustrations of the geology of Sussex, London, Lupton Relfe. 92 pp
  4. ↑ Owen, R. (1840–1845). Odontography. London: Hippolyte Baillière, 655 pp, 1–32
  5. ↑ Owen, R., 1842, Report on British fossil reptiles. Part II. Reports of the meetings of the British Association for the Advancement of Science. 11, pp 61-204
  6. ↑ Owen, R., 1878, Monograph on the fossil Reptilia of the Wealden and Purbeck Formations. Supplement VIII, (Goniopholis, Petrosuchus, and Suchosaurus). Palaeontolographical Society Monographs, 32, pp 1-15
  7. 1 2 Lydekker, R., 1888, Catalogue of the Fossil Reptilia and Amphibia in the British Museum (Natural History), Cromwell Road, S.W., Part 1. Containing the Orders Ornithosauria, Crocodilia, Dinosauria, Squamata, Rhynchocephalia, and Proterosauria. British Museum of Natural History, London. 309 pp
  8. ↑
    • Owen, R., 1884, A History of British Fossil Reptiles, Volume II. Cassell, London. 224 pp
  9. ↑ Sauvage, H. E. (1897–1898). Vertébrés fossiles du Portugal. Contribution à l’étude des poissons et des reptiles du Jurassique et du Crétacique. Lisbonne: Direction des Travaux géologiques du Portugal, 46p
  10. ↑ Malafaia, E.; Ortega, F.; Escaso, F.; Mocho, P., 2013, "Rediscovery of a lost portion of the holotype of Suchosaurus girardi (Sauvage, 1897-98), now related to the spinosaurid theropod Baryonyx", In: Torcida Fernández-Baldor, F.; Huerta, P. (Eds.). Abstract book of the VI International Symposium about Dinosaurs Palaeontology and their Environment pp 82-84
  11. ↑ Buffetaut, E., 2010, "Spinosaurs before Stromer: Early finds of spinosaurid dinosaurs and their interpretations", Geological Society, London, Special Publications. 343, pp 175-188
  12. ↑ Milner, A., 2003, "Fish-eating theropods: A short review of the systematics, biology and palaeobiogeography of spinosaurs". In: Huerta Hurtado and Torcida Fernandez-Baldor (eds.). Actas de las II Jornadas Internacionales sobre Paleontologýa de Dinosaurios y su Entorno (2001). pp 129-138
  13. ↑ Buffetaut, E. (2007). "The spinosaurid dinosaur Baryonyx (Saurischia, Theropoda) in the Early Cretaceous of Portugal." Geological Magazine, 144(6): 1021-1025. doi:10.1017/S0016756807003883
  14. ↑ Mateus, O.; Araújo, R.; Natário, C.; Castanhinha, R. (2011). "A new specimen of the theropod dinosaur Baryonyx from the early Cretaceous of Portugal and taxonomic validity of Suchosaurus" (PDF). Zootaxa. 2827: 54–68.
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