Anthracosauria is aparaphyleticorder of extinct reptile-likeamphibians (in the broad sense) that flourished during theCarboniferous andearly Permian periods, although precisely which species are included depends on one's definition of the taxon. "Anthracosauria" is sometimes used to refer to alltetrapods more closely related toamniotes such asreptiles,mammals, andbirds, than tolissamphibians such asfrogs andsalamanders. An equivalent term to this definition would beReptiliomorpha. Anthracosauria has also been used to refer to a smaller group of large, crocodilian-like aquatic tetrapods also known asembolomeres.
As originally defined bySäve-Söderbergh in 1934, the anthracosaurs are a group of usually large aquatic Amphibia from the Carboniferous and lower Permian. As defined byAlfred Sherwood Romer however, the anthracosaurs include all non-amniote "labyrinthodont"reptile-like amphibians, and Säve-Söderbergh's definition is more equivalent to Romer's suborderEmbolomeri. This definition was also used byEdwin H. Colbert andRobert L. Carroll in their textbooks of Vertebrate Palaeontology (Colbert 1969, Carroll 1988). Dr A. L. Panchen however preferred Säve-Söderbergh's original definition of Antracosauria in hisHandbuch der Paläoherpetologie, 1970.
Withcladistics things have changed again.Gauthier,Kluge andRowe (1988) defined Anthracosauria as aclade including "Amniota plus all other tetrapods that are more closely related to amniotes than they are to amphibians" (Amphibia in turn was defined by these authors as a clade includingLissamphibia and those tetrapods that are more closely related to lissamphibians than they are toamniotes). Similarly,Michel Laurin (1996) uses the term in acladistic sense to refer to only the most advancedreptile-like amphibians. Thus his definition includesDiadectomorpha,Solenodonsauridae and the amniotes. As Ruta, Coates and Quicke (2003) pointed out, this definition is problematic, because, depending on the exact phylogenetic position of Lissamphibia within Tetrapoda, using it might lead to the situation where some taxa traditionally classified as anthracosaurs, including even the genusAnthracosaurus itself, wouldn't belong to Anthracosauria. Laurin (2001) created a different phylogenetic definition of Anthracosauria, defining it as "the largest clade that includesAnthracosaurus russelli but notAscaphus truei". However,Michael Benton (2000, 2004) makes the anthracosaurs aparaphyletic order within the superorderReptiliomorpha, along with the ordersSeymouriamorpha andDiadectomorpha, thus making the Anthracosaurians the "lower" reptile-like amphibians. In his definition, the group encompass theEmbolomeri,Chroniosuchia and possibly the familyGephyrostegidae.
Many studies since have suggested that anthracosaurs or embolomeres are likelyreptiliomorphs closer toamniotes, but some recent studies either retain them as amphibians or argue that their relationships are still ambiguous and are more likely to be stem-tetrapods.[1][2][3]
Gauthier, J. A.; Kluge, A. G.; Rowe, T. (1988). "The early evolution of the Amniota". In M. J. Benton (ed.).The Phylogeny and Classification of the Tetrapods, Volume 1: Amphibians, Reptiles, Birds. Systematics Association Special Volume. Vol. 35A. Clarendon Press. pp. 103–155.
Panchen, A. L. (1970)Handbuch der Paläoherpetologie - Encyclopedia of Paleoherpetology Part 5a - Batrachosauria (Anthracosauria), Gustav Fischer Verlag - Stuttgart & Portland, 83 pp.,ISBN3-89937-021-Xweb pageArchived 2007-12-14 at theWayback Machine
^Hodnett, John-Paul M.; Lucas, Spencer G. (2018). "A nonmarine Late Pennsylvanian vertebrate assemblage in a marine bromalite from the Manzanita Mountains, Bernalillo County, New Mexico".New Mexico Museum of Natural History and Science Bulletin.79:251–260.
^Adams, Gabrielle R. (2020). "3. A phylogenetic analysis of NSM 994GF1.1 to determine the placement of embolomeres in the tetrapod tree".Description of Calligenethlon watsoni based on computed tomography and resulting implications for the phylogenetic placement of embolomeres (MSc thesis). Carleton University.
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