Microsauria
| Microsauria Temporal range: Late Carboniferous-Early Permian, 318.1–270.6Ma Possible descendant taxon Lissamphibia survives to present |
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| Microsauria diversity. (Hyloplesion (A), Pantylus (B), Pelodosotis (C) & Rhynchonkos (D)) | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Amphibia |
| Subclass: | †Lepospondyli |
| Order: | Microsauria* Dawson, 1863 |
| Suborders | |
Microsauria ("small lizards") is an extinct order of lepospondyl amphibians from the late Carboniferous and early Permian periods. It is the most diverse and species-rich group of lepospondyls.[1][2] Recently, Microsauria has been considered paraphyletic, as several other non-microsaur lepospondyl groups such as Lysorophia seem to be nested in it.[1][3][4] Microsauria is now commonly used as a collective term for the grade of lepospondyls that were originally classified as members of Microsauria.[2]
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.[5]
They are possible ancestors of the newts and salamanders, if that group did not arise from the temnospondyls along with the frogs and toads.[5]
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Distribution [edit]
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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,[6] Texas, Oklahoma, Ohio,[7] and Illinois, although remains have also been found in Nova Scotia.[8] 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.[9] 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 [edit]
Cladogram modified from Anderson (2001):[3]
| Lepospondyli |
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Cladogram from Ruta and Coates (2007):[4]
| "Microsauria" |
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References [edit]
- ^ a b Ruta, M.; Coates, M.I.; and Quicke, D.L.J. (2003). "Early tetrapod relationships revisited". Biological Reviews 78 (2): 251–345. doi:10.1017/S1464793102006103. PMID 12803423.
- ^ a b Bolt, J.R.; and 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.
- ^ a b 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.
- ^ a b Ruta, M.; and 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.
- ^ a b Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 55. ISBN 1-84028-152-9.
- ^ Thayer, D.W. (1985). "New Pennsylvanian lepospondyl amphibians from the Swisshelm Mountains, Arizona". Journal of Paleontology 59 (3): 684–700.
- ^ Hook, R. W.; and 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.
- ^ 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.; and Golubev, V.K. (2006). "Vyazniki biotic assemblage of the terminal Permian". Paleontological Journal 40 (Suppl. 4): S475–S481. doi:10.1134/S0031030106100078.
External links [edit]
- Microsauria in the Paleobiology Database
