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Stegotretus

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Stegotretus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Order: Microsauria
Family: Gymnarthridae
Genus: Stegotretus
Berman, Eberth & Brinkman, 1988
Type species
Stegotretus agyrus
Berman, Eberth & Brinkman, 1988

Stegotretus is an extinct genus of microsaur referred to the Pantylidae. It is known from the CarboniferousPermian boundary Cutler Formation exposures of New Mexico.[1]

History of study

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Material now referred to Stegotretus was first described (in brief) by Eberth & Berman (1983).[2] It was formally named by Berman et al. (1988).[1] The genus name comes from the Greek stegos ('roof') and tretos ('perforated') to refer to a large fenestra found on the palatine bone. The species name, S. agyrus, is said to be derived from Greek agyrus ('gathering' / 'crowd') in reference to the concentration of all known specimens in a small area.[1] The proper word in ancient Greek for 'gathering' / 'crowd' is however agora (ἀγορά), with the variant agyris (ἄγυρις) in the Aeolic dialect.[3] The holotype and referred materials are currently reposited in the Carnegie Museum of Natural History. A large number of partial to complete skulls and associated postcrania are known for this taxon.

Anatomy

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Despite the large number of specimens of Stegotretus, many are poorly preserved or distorted. Stegotretus is diagnosed by the presence of only two premaxillary teeth and by a large circular fenestra on the palatine. A contact between the maxilla and the quadratojugal and the absence of an entepicondylar foramen on the humerus separate it from the purportedly closely related Pantylus.

Relationships

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Stegotretus was classified as a pantylid by Berman et al. (1988). This has been validated by phylogenetic analyses that include the taxon,[4][5][6] although it is sometimes recovered as being more closely related to Sparodus than to Pantylus when all three taxa are sampled.[7] Below is the result of the analysis by Huttenlocker et al. (2013):

Microsauria

References

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  1. ^ a b c Berman, D.S.; Eberth, D.A.; Brinkman, D.B. (1988). "Stegotretus agyrus, a new genus and species of microsaur (amphibian) from the Permo-Pennsylvanian of New Mexico". Annals of Carnegie Museum. 57: 293–323.
  2. ^ Eberth, David A.; Berman, David S (1983). "Sedimentology and paleontology of Lower Permian fluvial redbeds of north-central New Mexico - preliminary report" (PDF). New Mexico Geology. 5: 21–25.
  3. ^ Liddell, H.G. & Scott, R. (1940). A Greek-English Lexicon. Revised and augmented throughout by Sir Henry Stuart Jones with the assistance of Roderick McKenzie.Oxford: Clarendon Press.
  4. ^ Huttenlocker, Adam K.; Pardo, Jason D.; Small, Bryan J.; Anderson, Jason S. (2013). "Cranial morphology of recumbirostrans (Lepospondyli) from the Permian of Kansas and Nebraska, and early morphological evolution inferred by micro-computed tomography". Journal of Vertebrate Paleontology. 33 (3): 540–552. doi:10.1080/02724634.2013.728998. ISSN 0272-4634.
  5. ^ Anderson, Jason S. (2001-03-01). "The Phylogenetic Trunk: Maximal Inclusion of Taxa with Missing Data in an Analysis of the Lepospondyli (Vertebrata, Tetrapoda)". Systematic Biology. 50 (2): 170–193. doi:10.1080/10635150151125833. ISSN 1076-836X.
  6. ^ Marjanović, David; Laurin, Michel (2019-01-04). "Phylogeny of Paleozoic limbed vertebrates reassessed through revision and expansion of the largest published relevant data matrix". PeerJ. 6: e5565. doi:10.7717/peerj.5565. ISSN 2167-8359. PMC 6322490. PMID 30631641.
  7. ^ Ruta, Marcello; Jeffery, Jonathan E.; Coates, Michael I. (2003-12-07). "A supertree of early tetrapods". Proceedings of the Royal Society of London. Series B: Biological Sciences. 270 (1532): 2507–2516. doi:10.1098/rspb.2003.2524. ISSN 1471-2954. PMC 1691537. PMID 14667343.