Thalattosuchus

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Thalattosuchus
Temporal range: Callovian - Oxfordian, 166–160  Ma
Metriorhynchus jaekeli - Naturmuseum Senckenberg - DSC02182.JPG
T. superciliosus, Senckenberg Museum of Frankfurt
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauria
Clade: Pseudosuchia
Clade: Crocodylomorpha
Suborder: Thalattosuchia
Family: Metriorhynchidae
Subfamily: Metriorhynchinae
Genus: Thalattosuchus
Young et al., 2020 [1]
Species:
T. superciliosus
Binomial name
Thalattosuchus superciliosus
(Blainville in Eudes-Deslongchamps, 1852)
Synonyms

Thalattosuchus is an extinct genus of marine crocodyliform that lived in the oceans during the Middle to Late Jurassic. Though the genus Thalattosuchus itself was named in 2020, its fossils have historically been included under the well known name Metriorhynchus as the species M. superciliosus, from which much of the research on the latter genus has been based upon. M. superciliosus was named as its own genus after a team of palaeontologists led by Mark Young in 2020 argued that the name Metriorhynchus could only be definitively applied to the type species, M. geoffroyii, and named Thalattosuchus ("sea crocodile", and from its parent group Thalattosuchia). [1] Not all researchers have accepted this split, and in 2022 another team led by Jonas le Mort have proposed Thalattosuchus be syonymised back into Metriorhynchus. [2]

Contents

Thalattosuchus was a carnivore that spent much, if not all, its life out at sea. No Thalattosuchus eggs or nests have been discovered, so little is known of the reptile's life cycle, unlike other large marine reptiles of the Mesozoic, such as plesiosaurs or ichthyosaurs which are known to have given birth to live young out at sea. [3] Where Thalattosuchus mated, whether on land or at sea, is currently unknown.

Discovery and species

T. superciliosus at the Museum national d'Histoire naturelle, Paris Metriorhynchus superciliosus.jpg
T. superciliosus at the Muséum national d'Histoire naturelle, Paris

Fossil specimens referrable to Thalattosuchus are known from Middle-Late Jurassic deposits of England, France and Germany. [1] [4]

The type species of Thalattosuchus was initially described as Crocodilus superciliosus in 1852. [5] During the 1860s the species superciliosus was moved to the genera Teleosaurus and Metriorhynchus . [1] The type specimen of superciliosus was largely neglected in the literature, and was figured in 2018 [6] and figured again in 2020 when the genus Thalattosuchus was created for the species. [1]

Only one species is recognised, the type species T. superciliosus.

The cladogram below is from an analysis by Mark Young and colleagues in 2020. [1]

Metriorhynchinae

Description

Life restoration of T. superciliosus Metriorhynchus superciliosum.jpg
Life restoration of T. superciliosus

Measuring 3–4.5 m (9.8–14.8 ft) in length, [7] Thalattosuchus was similar size to modern crocodiles. However, it had a streamlined body and a finned tail, making it a more efficient swimmer than modern crocodylian species. [8]

Palaeobiology

Salt glands

Thalattosuchus had nasal salt glands which, like the salt glands of all other marine reptiles, were used to remove excess salt. [9] This means that like Cricosaurus it would have been able to "drink" salt-water and eat equally salty prey, such as cephalopods, without dehydrating. [10]

See also

References

  1. 1 2 3 4 5 6 Young, M. T.; Brignon, A.; Sachs, S.; Hornung, J. J.; Foffa, D.; Kitson, J. J .N.; Johnson, M. M.; Steel, L. (2020). "Cutting the Gordian knot: a historical and taxonomic revision of the Jurassic crocodylomorph Metriorhynchus". Zoological Journal of the Linnean Society. 192 (2): 510–553. doi: 10.1093/zoolinnean/zlaa092 .
  2. Le Mort, J.; Martin, J. E.; Picot, L.; Hua, S. (2022). "First description of the most complete Metriorhynchus aff. superciliosus (Thalattosuchia) specimen from the Callovian of the Vaches-Noires cliffs (Normandy, France) and limitations in the classification of Metriorhynchidae". Annales de Paléontologie. 108 (3): 102539. Bibcode:2022AnPal.10802539L. doi:10.1016/j.annpal.2022.102539. ISSN   0753-3969. S2CID   254175334.
  3. Metriorhynchus fact files
  4. Steel R. 1973. Crocodylia. Handbuch der Paläoherpetologie, Teil 16. Stuttgart: Gustav Fischer Verlag,116 pp.
  5. Eudes-Deslongchamps, J. A.; Blainville, H. M. D. (de) (1852). Lettres sur les crocodiles vivants et fossiles. Caen: A. Hardel. pp. 1–38.
  6. Brignon, A. (2018). "Contexte historique de la collection Félix de Roissy (1771-1843) de reptiles marins jurassiques des Vaches Noires". Geodiversitas. 40 (1): 43–68. Bibcode:2018Geodv..40...43B. doi:10.5252/geodiversitas2018v40a2.
  7. Young, M.T.; Bell, M.A.; De Andrade, M.B.; Brusatte, S.L. (2011). "Body size estimation and evolution in metriorhynchid crocodylomorphs: Implications for species diversification and niche partitioning". Zoological Journal of the Linnean Society. 163 (4): 1199–1216. doi: 10.1111/j.1096-3642.2011.00734.x .
  8. Massare JA. 1988. Swimming capabilities of Mesozoic marine reptiles; implications for method of predation. Paleobiology14 (2):187-205.
  9. Gandola, R.; Buffetaut, E.; Monaghan, N.; Dyke, G. (2006). "Salt glands in the fossil crocodile Metriorhynchus". Journal of Vertebrate Paleontology. 26 (4): 1009–1010. doi:10.1671/0272-4634(2006)26[1009:SGITFC]2.0.CO;2.
  10. Fernández M, Gasparini Z. 2008. Salt glands in the Jurassic metriorhynchid Geosaurus: implications for the evolution of osmoregulation in Mesozoic crocodyliforms. Naturwissenschaften95: 79-84.