Biology:Simoedosaurus

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Short description: Extinct genus of reptiles


Simoedosaurus
Temporal range: Paleocene-Eocene
Simoedosaurus lemoinei Cernay.JPG
Fossil
Scientific classification e
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Choristodera
Suborder: Neochoristodera
Genus: Simoedosaurus
Gervais, 1877
Type species
Simoedosaurus lemoinei
Gervais, 1877

Simoedosaurus is an extinct reptile known from the Paleocene of North America, Europe and western Asia,[1] and a member of the Choristodera, a group of aquatic reptiles that lived in the Northern Hemisphere from the Jurassic to the early Cenozoic.

A second species, S. dakotensis got its own genus, Kosmodraco, in 2022.[2]

Taxonomy

French paleontologist Paul Gervais described Simoedosaurus in 1877.

Though similar to and contemporaneous, Simoedosaurus is not closely related to the North American Champsosaurus, instead it appears to be most closely related to Tchoiria and Ikechosaurus from the Early Cretaceous of Asia. It therefore may represent a species that immigrated into North America from Asia in the wake of the Cretaceous-Tertiary mass extinction event, though the absence of choristoderes in the Late Cretaceous of Asia makes this merely a paleogeographical speculation.[3]

Biology

Simoedosaurus was an aquatic predator, specialised to a fully aquatic lifestyle; though Champsosaurus might have still come ashore to lay eggs, ovovivipary is known in other choristoderes.[4] It in particular possesses broader, stronger jaws than other longirostrine choristoderes, including its closest relatives, suggesting that it was capable of tackling larger prey.[5]

Simoedosaurus does occur in sites where aquatic crocodilians are present, including brevirostrine forms like Borealosuchus; the extent of competition between both groups, if there was any, is still unresolved.[6]

Like other neo-choristoderes it has nasal conchae, suggesting it could regulate its own body temperature, explaining its ability to live in cold waters.[7]

Range

The earliest records of Simoedosaurus are from the Early Paleocene (Puercan Land Mammal Age) of Saskatchewan. It persisted until the Late Palaecene in North America, and has also been found in the Late Paleocene of France. The youngest remains seem to occur in the Eocene of Kazakhstan.[8]

References

  1. "The first choristoderes (Diapsida, Choristodera) from the Paleogene of Asia.". Paleontological Journal 39 (1): 79–84. 2005. 
  2. "High morphological disparity in a bizarre Paleocene fauna of predatory freshwater reptiles". BMC Ecology and Evolution 22 (1): 34. March 2022. doi:10.1186/s12862-022-01985-z. PMID 35313822. 
  3. "Choristoderes and the freshwater assemblages of Laurasia.". Journal of Iberian Geology 36 (2): 253–274. 2010. doi:10.5209/rev_JIGE.2010.v36.n2.11. 
  4. "Embryos of Early Cretaceous Choristodera (Reptilia) from the Jehol Biota in western Liaoning, China.". Journal of the Paleontological Society of Korea 22 (1): 111–118. 2006. 
  5. "Morphology and function of the palatal dentition in Choristodera". Journal of Anatomy 228 (3): 414–29. March 2016. doi:10.1111/joa.12414. PMID 26573112. 
  6. R. Matsumoto and S. E. Evans. 2010. Choristoderes and the freshwater assemblages of Laurasia. Journal of Iberian Geology 36(2):253-274
  7. Dudgeon TW (2019). The internal cranial anatomy of Champsosaurus lindoei and its functional implications (Doctoral thesis). Carleton University.
  8. "The first choristoderes (Diapsida, Choristodera) from the Paleogene of Asia.". Paleontological Journal 39 (1): 79–84. 2005. 

Wikidata ☰ Q2164813 entry