Kawasphenodon is an extinct genus of sphenodontian reptile, known from the Late Cretaceous and Paleocene of Patagonia in South America. The type species, K. expectatus, was described in 2005 from jaw fragments found in late Campanian aged sediments in the Los Alamitos Formation, the jaw when complete was estimated to be 11 cm long, making it among the largest known sphenodontians.[1] A second species, K. peligrensis, around 1/3 the size of the type species, was described in 2014 also from jaw fragments in early Paleocene (Danian) sediments of the Salamanca Formation, making it the youngest known definitive representative of Rhynchocephalia outside of New Zealand.[2] In the original description, it was found to be a member of Sphenodontidae, in some other subsequent analyses it was found to be a member of Opisthodontia. A 2020 analysis of rhyncocephalian relationships found it to be outside Opisthodontia, and instead a member of the Sphenodontinae as the closest known relative of the tuatara, with an estimated divergence between the two genera in the Early Cretaceous.[3] Other subsequent studies have endorsed its placement as a member of Sphenodontidae.[4] Like most other rhynchocephalians, the teeth are acrodont, with a deep dentary, and it probably had an omnivorous habit.[2]
| Kawasphenodon | |
|---|---|
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Rhynchocephalia |
| Suborder: | Sphenodontia |
| Genus: | †Kawasphenodon Apesteguía, 2005 |
| Type species | |
| Kawasphenodon expectatus Apesteguía, 2005
| |
| Other species | |
| |
References
edit- ^ Apesteguía, Sebastián (2005-12-01). "A Late Campanian sphenodontid (Reptilia, Diapsida) from northern Patagonia". Comptes Rendus Palevol. 4 (8): 663–669. Bibcode:2005CRPal...4..663A. doi:10.1016/j.crpv.2005.06.003. ISSN 1631-0683.
- ^ a b Apesteguía, Sebastián; Gómez, Raúl O.; Rougier, Guillermo W. (2014-10-07). "The youngest South American rhynchocephalian, a survivor of the K/Pg extinction". Proceedings of the Royal Society B: Biological Sciences. 281 (1792): 20140811. doi:10.1098/rspb.2014.0811. ISSN 0962-8452. PMC 4150314. PMID 25143041.
- ^ Simões, Tiago R.; Caldwell, Michael W.; Pierce, Stephanie E. (December 2020). "Sphenodontian phylogeny and the impact of model choice in Bayesian morphological clock estimates of divergence times and evolutionary rates". BMC Biology. 18 (1): 191. doi:10.1186/s12915-020-00901-5. ISSN 1741-7007. PMC 7720557. PMID 33287835.
- ^ Agnolín, Federico L.; Aranciaga Rolando, A. Mauro; Chimento, Nicolás R.; Novas, Fernando E. (October 2023). "New small reptile remains from the Late Cretaceous of Patagonia increase morphological diversity of sphenodontids (Lepidosauria)". Proceedings of the Geologists' Association. 135: 36–44. doi:10.1016/j.pgeola.2023.09.007.