Microsauria
Microsauria ("small lizards") is an extinct, possibly polyphyletic[1] order of tetrapods from the late Carboniferous and early Permian periods. It is the most diverse and species-rich group of lepospondyls.[2][3] Recently, Microsauria has been considered paraphyletic, as several other non-microsaur lepospondyl groups such as Lysorophia seem to be nested in it.[2][4][5] Microsauria is now commonly used as a collective term for the grade of lepospondyls that were originally classified as members of Microsauria.[3]
| Microsauria | |
|---|---|
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| Microsauria diversity. (Hyloplesion (A), Pantylus (B), Pelodosotis (C) & Rhynchonkos (D)) | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Subclass: | †Lepospondyli |
| Order: | †"Microsauria" Dawson, 1863 |
| Subgroups | |
The microsaurs all had short tails and small legs, but were otherwise quite varied in form. The group included lizard-like animals that were relatively well-adapted to living on dry land, burrowing forms, and others that, like the modern axolotl, retained their gills into adult life, and so presumably never left the water.[6]
Distribution
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Microsaur remains have been found from Europe and North America in Late Carboniferous and Early Permian localities. Most North American microsaurs have been found in the United States in Arizona,[7] Texas, Oklahoma, Ohio,[8] Illinois, as well as Kansas and Nebraska,[9] although remains have also been found in Nova Scotia.[10] In Europe, microsaurs are known from Germany and the Czech Republic. Possible microsaur remains have also been found from strata in the town of Vyazniki in the Vladimir Oblast of Russia.[11] These strata are Late Permian in age, near the Permo-Triassic boundary. The microsaur material at Vyazniki may be the youngest record of microsaurs, and would extend their range by around 20 million years.
Classification
Cladogram modified from Anderson (2001):[4]
| Lepospondyli |
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Cladogram from Ruta and Coates (2007):[5]
| "Microsauria" |
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Cladistic analysis by Pardo et al. (2017) places recumbirostran microsaurs and lysorophians as members of Amniota.[12]
References
- https://onlinelibrary.wiley.com/doi/abs/10.1002/spp2.1316
- Ruta, M.; Coates, M.I.; Quicke, D.L.J. (2003). "Early tetrapod relationships revisited" (PDF). Biological Reviews. 78 (2): 251–345. doi:10.1017/S1464793102006103. PMID 12803423.
- Bolt, J.R.; Rieppel, O. (2009). "The holotype skull of Llistrofus pricei Carroll and Gaskill, 1978 (Microsauria: Hapsidopareiontidae)". Journal of Paleontology. 83 (3): 471–483. doi:10.1666/08-076.1.
- Anderson, J.S. (2001). "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:10.1080/10635150119889. PMID 12116927.
- Ruta, M.; Coates, M.I. (2007). "Dates, nodes, and character conflict: addressing the lissamphibian origin problem". Journal of Systematic Palaeontology. 5: 69–122. doi:10.1017/S1477201906002008.
- Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 55. ISBN 978-1-84028-152-1.
- Thayer, D.W. (1985). "New Pennsylvanian lepospondyl amphibians from the Swisshelm Mountains, Arizona". Journal of Paleontology. 59 (3): 684–700.
- Hook, R. W.; Baird, D. (1986). "The Diamond Coal Mine of Linton, Ohio, and its Pennsylvanian-Age vertebrates". Journal of Vertebrate Paleontology. 6 (2): 174–190. doi:10.1080/02724634.1986.10011609.
- Huttenlocker, A. K.; Pardo, J. D.; Small, B. J.; Anderson, J. 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.
- Steen, M.C. (1934). "The amphibian fauna from the South Joggins, Nova Scotia". Proceedings of the Zoological Society of London. 104 (3): 465–504. doi:10.1111/j.1096-3642.1934.tb01644.x.
- Sennikov, A.G.; Golubev, V.K. (2006). "Vyazniki biotic assemblage of the terminal Permian" (PDF). Paleontological Journal. 40 (Suppl. 4): S475–S481. doi:10.1134/S0031030106100078.
- Jason D. Pardo; Matt Szostakiwskyj; Per E. Ahlberg; Jason S. Anderson (2017). "Hidden morphological diversity among early tetrapods". Nature. 546 (7660): 642–645. doi:10.1038/nature22966. PMID 28636600.
External links
- Microsauria in the Paleobiology Database
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