Lewisuchus
Lewisuchus | |
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Life reconstruction of Lewisuchus admixtus | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dracohors
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Family: | †Silesauridae |
Genus: | †Lewisuchus Romer, 1972
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Species: | †L. admixtus
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Binomial name | |
†Lewisuchus admixtus Romer, 1972
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Synonyms | |
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Lewisuchus is a
History
The first remains of Lewisuchus were discovered in a 1964-1965 joint expedition by the Museo de La Plata and Harvard's Museum of Comparative Zoology. These remains were preserved in a carbonate nodule recovered from the Chañares Formation of Argentina. It contained a partial skeleton of Lewisuchus, including parts of the skull, braincase, many vertebrae, scapulocoracoids, humeri, and tibiae.[8] A gomphodont and bones from several other species of archosaurs were also preserved in the same nodule.[7] An isolated lower jaw and foot bones were also initially referred to Lewisuchus, but these were later identified as belong to proterochampsids. This is also likely true of an astragalus found alongside the skeleton.[8]
Alfred Romer named Lewisuchus as a new genus in 1972, based on the partial skeleton which at that point was stored at the Museo de La Plata with catalogue number 64-XI-14-14. The generic name honored Arnold D. Lewis, the chief preparator who discovered the skeleton while working on the recovered nodule. Like many other early archosaurs and crocodilian relatives, it also references Soûkhos, the Greek name for the Egyptian crocodile god Sobek. The species name "admixtus" refers to the mixture of different species preserved along with the holotype.[7] The holotype is now housed at the Paleontology Museum at the National University of La Rioja (PULR) with catalogue number PULR 01.[8]
Pseudolagosuchus
Another Chañares
Despite not sharing much overlapping material, some paleontologists have proposed that Pseudolagosuchus major represented the same species of animal as Lewisuchus admixtus. If this is demonstrated to be the case, the name Lewisuchus would have priority over Pseudolagosuchus due to having been named earlier. Arcucci argued towards synonymizing the two as early as 1997. A 2010 study in the Journal Nature by Nesbitt et al. also made a case for their synonymy, as they were approximately the same size, came from the same locality and strata, and both were found to be basal members of the recently named family Silesauridae.[11] Many other studies supported these arguments, sometimes even scoring the two as a single taxon in their phylogenetic analyses.[12] Several hindlimb, hip, and vertebral fossils (PVL 3456, PULR-V 112 and PULR-V 113) have additionally been referred to Lewisuchus based on their similarity to Pseudolagosuchus remains.[8][13] However, Bittencourt et al.'s 2014 redescription of the Lewisuchus holotype refrained from synonymizing the two due to a lack of data, with the only overlapping material being the tibia and a few cervical (neck) vertebrae. No unambiguous characteristics were shared between these scraps, and one tibia referred to Pseudolagosuchus (Novas's 'UPLR 53') seemed to have a curvature different from that of Lewisuchus's holotype.[8]
A new specimen of Lewisuchus discovered in 2013 was described by
References
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- PMID 31720108.
- PMID 27839975.
- ^ a b c Romer, A. S. (11 August 1972). "The Chañares (Argentina) Triassic reptile fauna; XIV, Lewisuchus admixtus, gen. et sp. nov., a further thecodont from the Chañares beds". Breviora. 390: 1–13.
- ^ S2CID 56155733.
- ^ Arcucci, Andrea (1987). "Un nuevo Lagosuchidae (Thecodontia-Pseudosuchia) de la fauna de Los Chanares (edad reptil Chanarense, Triasico Medio), La Rioja, Argentina" (PDF). Ameghiniana. 24 (1–2): 89–94.
- JSTOR 4523770.
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- PMID 31444989.