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Metriorhynchidae
Fossil range: Bajocian - Valanginian
170-136 Ma
Metriorhynchus supercil1DB
Metriorhynchus
Scientific classification

Class:

Sauropsida

Subclass:

Diapsida

Infraclass:

Archosauromorpha

(Unranked) :

Mesoeucrocodylia

Suborder:

Thalattosuchia

Family:

Metriorhynchidae Fitzinger, 1843 [1]

Genera:

Synonyms:

Metriorhynchids is an extinct clade of fully-aquatic crocodyliforms that lived in seas of the Jurassic and Cretaceous periods. Their fore-legs were reduced and paddle-like, and unlike living crocodilians, they lost their osteoderms ("armour scutes"). Their body shape maximised hydrodynamy (swimming efficiency), as did having a shark-like tail fin.[8]

Metriorhynchids were the only group of archosaurs to become fully adapted to marine life, becoming pelagic in lifestyle.[9]

The name Metriorhynchidae was coined by the Austrian zoologist Leopold Fitzinger in 1843.[1]

Geographical distributionEdit

The family has a wide geographic distribution, with material found in Argentina, Chile, Cuba, England, France, Germany, Italy, Mexico, Poland, Russia and Switzerland.[9]

GeneraEdit

The type genus for Metiorhynchidae is Metriorhynchus from the Middle to Late Jurassic.[9] Other genera included within this family are Teleidosaurus, Geosaurus, Dakosaurus and Enaliosuchus. Genera considered nomina dubia ("doubtful names") within this family are Aggiosaurus [10] and Neustosaurus.[11]

The species classified as Purranisaurus and Suchodus are currently considered to belong within Metriorhynchus; if correct, this makes Purranisaurus and Suchodus junior synonyms of Metriorhynchus. Various palaeontologists have regarded the genus Cricosaurus as a junior synoynm of either Metriorhynchus, Geosaurus or Dakosaurus.[9]

The genus Capelliniosuchus, was once thought to be a metriorhynchid similar to Dakosaurus.[12] However, Sirotti demonstrated that it is a junior synonym of Mosasaurus.[13]

However, recent phylogenetic analyses cast doubt on the idea that many genera form a natural group (i.e. evolved from a common ancestor). The monophyly of Metriorhynchus,[14][15][16]Teleidosaurus,[15][17]Geosaurus,[15][16][17] and Dakosaurus[15] has been questioned. The monophyly of the poorly known genus Cricosaurus is also not supported, while Purranisaurus may be a distinct genus of metriorhynchid.[15]

Genus Status Age Location Description Images
Nomen dubium. Late Jurassic. Europe. A poorly preserved marine crocodile that was originally mistaken for a new kind of megalosaurid dinosaur.
Junior synonym. Late Jurassic. Europe. — junior synonym Geosaurus
Lapsus calami. N/A N/A Misspelling of Capelliniosuchus
Misidentified Mosasaur. N/A N/A Once thought to be a metriorhynchid, now known to be a mosasaur.
Valid. Late Jurassic. Europe. Poorly known genus of Metriorhynchidae.
Lapsus calami. lapsus calami of Dakosaurus
Valid. Late Jurassic-Early Cretaceous. Europe, North America and South America.
Valid. Early Cretaceous. Europe.
Valid. Late Jurassic-Early Cretaceous. Europe, North America and South America.
Junior synonym. — junior synonym of Geosaurus
Lapsus calami. lapsus calami of Metriorhynchus
Valid. Middle-Late Jurassic Europe and South America.
Nomen dubium Early Cretaceous. Europe. — possible junior synonym of Dakosaurus or Geosaurus
Junior synonym. — junior synonym of Metriorhynchus
Junior synonym. — junior synonym of Geosaurus
Junior synonym. — junior synonym of Metriorhynchus
Valid. Middle Jurassic. Europe.

See alsoEdit

ReferencesEdit

  1. ^ a b Fitzinger LJFJ. 1843. Systema Reptilium. Wien: Braumüller et Seidel, 106 pp.
  2. ^ Quenstedt FA. 1856. Sonst und Jetzt: Populäre Vortäge über Geologie. Tübingen: Laupp, 131.
  3. ^ Cuvier G. 1824. Sur les ossements fossiles de crocodiles, 5. In: Dufour & D'Occagne, eds. Recherches sur les ossements fossiles, 2nd édition. Paris: 143-160
  4. ^ Koken E. 1883. Die reptilian der norddeutschen unteren Kreide. Zeitschrift deutschen Geologischen Gesellschaft 35: 735-827.
  5. ^ Meyer H Von. 1830. Achte Versammlung der Naturforscher und Aerzte zu Heidelberg im September 1829. Isis von Oken, 1830: 517-519.
  6. ^ Eudes-Deslongchamps, E. 1869. Notice sur les animaux fossiles de la famille des Téléosauriens recueillis en Normandie. Mémoires Acad. Imp. Sci. et Arts et Belles-Lettres: 31-80.
  7. ^ Andrews CW. 1913. A descriptive catalogue of the marine reptiles of the Oxford Clay, Part Two. London: British Museum (Natural History), 206 pp.
  8. ^ Fraas E. 1902. Die Meer-Krocodilier (Thalattosuchia) des oberen Jura unter specieller Berücksichtigung von Dacosaurus und Geosaurus. Paleontographica 49: 1-72.
  9. ^ a b c d Steel R. 1973. Crocodylia. Handbuch der Paläoherpetologie, Teil 16. Stuttgart: Gustav Fischer Verlag,116 pp.
  10. ^ Buffetaut E. 1982. Aggiosaurus nicaeensis Ambayrac, 1913, from the Upper Jurassic of south-eastern France: A marine crocodilian, not a dinosaur. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte (8): 469-475.
  11. ^ Buffetaut, E. 1982. Radiation évolutive, paléoécologie et biogéographie des Crocodiliens mésosuchienes. Mémoires Societé Geologique de France 142: 1–88.
  12. ^ Simonelli V. 1896. Intoro agli avanzi di coccodrilliano scoperti a San Valentino (provincial di Reggio Emilia) nel 1886. Atli della Reale Accademia dei Lincei, series Qunita Rendiconti 5 (2): 11-18.
  13. ^ Sirotti A. 1989. Mosasaurus hoffmanni Mantell, 1828 (Reptilia) nelle <<argille scagliose>> di S. Valentino (Reggio E.). Atti della società dei naturalisti e matematici di Modena 120: 135-146.
  14. ^ Gasparini Z, Pol D, Spalletti LA. 2006. An unusual marine crocodyliform from the Jurassic-Cretaceous boundary of Patagonia. Science 311: 70-73.
  15. ^ a b c d e Young MT. 2007. The evolution and interrelationships of Metriorhynchidae (Crocodyliformes, Thalattosuchia). Journal of Vertebrate Paleontology 27 (3): 170A.
  16. ^ a b Wilkinson LE, Young MT, Benton MJ. 2008. A new metriorhynchid crocodilian (Mesoeucrocodylia: Thalattosuchia) from the Kimmeridgian (Upper Jurassic) of Wiltshire, UK. Palaeontology 51 (6): 1307-1333.
  17. ^ a b Mueller-Töwe IJ. 2005. Phylogenetic relationships of the Thalattosuchia. Zitteliana A45: 211–213.

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