Anthracosauria

Anthracosauria Temporal range: Late Devonian–Early Triassic PreЄ Є O S D C P T J K Pg N
Gephyrostegus bohemicus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Superclass:	Tetrapoda
Class:	Amphibia/sensu lato
Superorder:	Reptiliomorpha
Order:	Anthracosauria Säve-Söderbergh, 1934
Groups
Embolomeri Chroniosuchia Gephyrostegida Seymouriamorpha Diadectomorpha

Anthracosauria is an order of extinct reptile-like amphibians that flourished during the Carboniferous and early Permian periods, although precisely which species are included depends on one's definition of the taxon.

File:Empedias molaris.JPG

Empedias molaris bones

Various definitions

As originally defined by Säve-Söderbergh in 1934, the anthracosaurs are a group of usually large aquatic Amphibia from the Carboniferous and lower Permian. As defined by Alfred Sherwood Romer however, the anthracosaurs include all non-amniote "labyrinthodont" reptile-like amphibians, and Säve-Söderbergh's definition is more equivalent to Romer's suborder Embolomeri. This definition was also used by Edwin H. Colbert and Robert 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 his Handbuch der Paläoherpetologie, 1970.

With cladistics things have changed again. Gauthier, Kluge and Rowe (1988) defined Anthracosauria as a clade 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 including Lissamphibia and those tetrapods that are more closely related to lissamphibians than they are to amniotes). Similarly, Michel Laurin (1996) uses the term in a cladistic sense to refer to only the most advanced reptile-like amphibians. Thus his definition include the (Diadectomorpha and 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 genus Anthracosaurus itself, wouldn't belong to Anthracosauria. Laurin (2001) created a different phylogenetic definition of Anthracosauria, defining it as "the largest clade that includes Anthracosaurus russelli but not Ascaphus truei". However, Michael Benton (2000, 2004) makes the anthracosaurs a paraphyletic order within the superorder Reptiliomorpha, along with the orders Seymouriamorpha and Diadectomorpha, thus making the Anthracosaurians the "lower" reptile-like amphibians. In his definition, the group encompass the Embolomeri, Chroniosuchia and possibly the family Gephyrostegidae.

Etymology

The name "Anthracosauria" is Greek ('coal lizards'), because many of its fossils were found in the Coal Measures.

References and external links

• Benton, M. J. (2004), Vertebrate Palaeontology, Blackwell Science Ltd 3rd ed. - see also taxonomic hierarchy of the vertebrates, according to Benton 2004
• Carroll, R. L., 1988: Vertebrate Paleontology and Evolution. W. H. Freeman and company, New York
• Clack, J. A. (2002), Gaining Ground: the Origin and Evolution of Tetrapods Indiana Univ. Press, 369 pp.
• Colbert, E. H. (1969), Evolution of the Vertebrates, John Wiley & Sons Inc (2nd ed.)
• Laurin, Michel (1996) Terrestrial Vertebrates - Stegocephalians: Tetrapods and other digit-bearing vertebrates
• Palaeos Anthracosauroidea
• Panchen, A. L. (1970) Handbuch der Paläoherpetologie - Encyclopedia of Paleoherpetology Part 5a - Batrachosauria (Anthracosauria), Gustav Fischer Verlag - Stuttgart & Portland, 83 pp., ISBN 3-89937-021-X web page
• Systema Naturae 2000 / Classification Order Anthracosauria