Teleosaurus

Teleosaurus (from Greek: τέλειος téleios, 'perfect' and Greek: σαῦρος saûros, 'lizard')^[1] is an extinct genus of teleosaurid crocodyliform found in the Middle Jurassic Calcaire de Caen Formation of France.^[2] It was approximately 3 metres (10 ft) in length.^[3] The holotype is MNHN AC 8746, a quarter of a skull and other associated postcranial remains, while other fragmentary specimens are known.^[4] The type species is T. cadomensis,^[5] but a second species, T. geoffroyi may also exist.^[6] It was previously considered a wastebasket taxon, with many other remains assigned to the genus.^[7][4]

Teleosaurus Temporal range: Bajocian–Bathonian, 171–164 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Holotype skull of T. cadomensis (MNHN AC 8746) seen from multiple angles
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Archosauria
Clade:	Pseudosuchia
Clade:	Crocodylomorpha
Clade:	Crocodyliformes
Suborder:	†Thalattosuchia
Family:	†Teleosauridae
Subfamily:	†Teleosaurinae
Genus:	†Teleosaurus Geoffroy, 1825 vide Cuvier, 1824
Type species
†Teleosaurus cadomensis (Lamouroux, 1820)
Other species
T. geoffroyi? Eudes-Deslongchamps, 1868c
Synonyms
Crocodylus cadomensis Lamouroux, 1820 Teleosaurus asthenodirus Owen, 1842 Teleosaurus brevior Owen, 1884 Teleosaurus eucephalus Seeley, 1880 Teleosaurus gladius Eudes-Deslongchamps, 1868c Teleosaurus lacunosae Quenstedt, 1858 Teleosaurus latifrons Owen, 1884 Teleosaurus minimus Quenstedt, 1852 Teleosaurus ornati Quenstedt, 1852 Teleosaurus soemmeringii Holl, 1829 Teleosaurus subulidens Phillips, 1871

History

Skull illustration

Dorsal osteoderms (NHMUK PV R 4207) of T. cadomensis from Normandy, which have been in the collection of the Field Museum of Natural History since 1914

Teleosaur remains have been known to science since at least 1758,^[8][9] although at first scientists believed the remains belonged to extinct crocodiles and alligators, and remains that have at one point in time been attributed to Teleosaurus (and Steneosaurus) have been known to science since at least 1800.^[10][11] The holotype was discovered during the early 19th century by Pierre Tesson before he traded it with Lamoroux. Teleosaurus was briefly noted on by Jean Vincent Félix Lamouroux in 1820 as Crocodilus cadomensis and then he sent the specimen to Georges Cuvier.^[12] It was fully described by Cuvier in 1824,^[13] but it was not published until a year later by Étienne Geoffroy Saint-Hilaire.^[5]

The second species attributed to Teleosaurus, T. soemmeringii (now a synonym of T. cadomensis), was named in 1829.^[14] In 1842, T. asthenodeirus, was named.^[15] T. minimus and T ornati were named in 1852 and it is now firmly a synonym of T. cadomensis.^[16] Friedrich August von Quenstedt also added T. lacunosae several years later in 1858. Eudes-Deslongchamps followed in 1868, naming the two species T. geoffroyi and T. gladius - both are based on remains destroyed in Caen in 1944. T. geoffroyi, described on the basis of now destroyed mandibular fragments, was considered a valid species by Vignaud (1995),^[17] but it was made a probable synonym of T. cadomensis in 2020.^[4] Richard Owen added T. brevior and T. latifrons to Teleosaurus in 1884.^[18]

In 2019, the taxonomy of Teleosauroidea was reviewed and T. cadomensis was seen as the only valid species.^[7] The rest of the known species were absorbed into T. cadomensis or other genera.^[7][4] This study was published in October 2020.^[4]

Description

Teleosaurus had highly elongate jaws, similar to those of a modern gharial.^[15] It had a long, slender, body, with a sinuous tail that would have helped propel it through the water. Its forelimbs were remarkably short, and would probably have been held close to the body when swimming to improve the animal's streamlining. Unlike modern crocodilians, it lived in the open ocean, and it probably caught fish and squid with its sharp, needle-like teeth.^[19]

Known remains

Teleosaurus cadomensis is known from the following specimens:^[4]

• MNHN AC 8746 (holotype): quarter of a skull and other associated postcranial remains
• NHMUK PV OR 119a: dorsal osteoderms
• NHMUK PV R 4207: dorsal osteoderms
• NHMUK PV OR 32588: dorsal, sacral and caudal vertebrae
• NHMUK PV OR 32657: femur
• NHMUK PV OR 32680: ischium
• NHMUK PV OR 33124 mandibular symphysis
• NHMUK PV OR 39788: partial rostrum
• NHMUK PV R 880 and NHMUK PV R 880a: additional casts

References

• Paleontology portal

1. Roberts, George (1839). An etymological and explanatory dictionary of the terms and language of geology. London: Longman, Orme, Brown, Green, & Longmans. p. 169. Retrieved 1 January 2022.
2. Weishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Europe)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 538–541. ISBN 0-520-24209-2.
3. P. H. Phizackerley (1951). A revision of the Teleosauridae in the Oxford University Museum and the British Museum. The Annals and Magazine of Natural History 12(4): 1170–1192.
4. Johnson, Michela M.; Young, Mark T.; Brusatte, Stephen L. (2020). "The phylogenetics of Teleosauroidea (Crocodylomorpha, Thalattosuchia) and implications for their ecology and evolution". PeerJ. 8: e9808. doi:10.7717/peerj.9808. PMC 7548081. PMID 33083104.
5. Geoffroy Saint-Hilaire, É. (1825) Recherches sur l’organisation des gavials. Mém Mus Natl Hist Nat 12: 97–155.
6. P. H. Phizackerley. (1951). A revision of the Teleosauridae in the Oxford University Museum and the British Museum. The Annals and Magazine of Natural History 12(4):1170-1192
7. "The taxonomy, systematics and ecomorphological diversity of Teleosauroidea (Crocodylomorpha, Thalattosuchia), and the evaluation of the genus 'Steneosaurus'". Archives of the University of Edinburgh. 2019.
8. Chapman, W. (1758) An account of the fossile bones of an allegator, found on the sea-shore, near Whitby in Yorkshire. Philosophical Transactions of The Royal Society of London 50:688-691
9. Morton, C. and Wooler, M. (1758) A Description of the Fossil Skeleton of an Animal Found in the Alum Rock Near Whitby. Philosophical Transactions (1683–1775) 50:786-790
10. Cuvier, G. (1800) On a new species of fossil crocodile [in French] Bulletin de la Sociéte philomatique de Paris 2:159
11. Cuvier, G. (1808) On the fossil bones of crocodiles: and especially on those around Le Havre and Honfleur, with remarks on the skeletons of the saurians of Thuringia [in French] Annales du Muséum d'histoire naturelle 12:73-110
12. Lamouroux, M (1820) Sur le crocodile fossile trouvé dans les carrières du Bourg d'Allemagne, a un quart de lieue de Caen. Annales générales des Sciences physiques.
13. Cuvier, G. (1824) Article IV Des os de deux espèces inconnues de Gavials; trouvés pêle-mêle près de Honfleur et du Hâvre. Sur les Ossemens Fossiles. Nouvelle édition, Tome Cinquieme, Partie 2 Paris: Dufour & d’Occagne. 143–160.
14. F. Holl. (1829). Handbuch der Petrefactenkunde, mit einer Einleitung über die Vorwelt der organischen Wesen auf der Erde von Dr. Ludwig Choulant 1:1-115
15. R. Owen (1842). Report on British fossil reptiles, part II. Report of the British Association for the Advancement of Science 11: 60-204.
16. Von Quenstedt, F. A. (1852). Handbuch der Petrefaktenkunde. Tübingen: Laupp.
17. Vignaud, P. (1995). “The Thalattosuchia, Mesozoic marine crocodiles: phylogenetic systematics, paleoecology, biochronology and palaeogeographical implications." Unpublished PhD thesis, University of Poitiers p.410
18. R. Owen. (1884). A History of British Fossil Reptiles, Part III. 1-199
19. Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 99. ISBN 1-84028-152-9.