Anthracosauria
Encyclopedia
Anthracosauria is an order of extinct reptile-like amphibian
s that flourished during the Carboniferous
and early Permian periods, although precisely which species are included depends on one's definition of the taxon.
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. 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. 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.
('coal lizards'), because many of its fossils were found in the Coal Measures
.
Amphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...
s that flourished during the Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...
and early Permian periods, although precisely which species are included depends on one's definition of the taxon.
Various definitions
As originally defined by Säve-SöderberghGunnar Säve-Söderbergh
Gunnar Säve-Söderbergh was a Swedish palaeontologist and geologist. Säve-Söderbergh was born at Falun, the son of the neurologist Gotthard Söderbergh and Inga Säve. He passed his G.C.E. at Gothenburg in 1928 and took bachelor's and licentiate's degrees at Uppsala University in 1931 and 1933,...
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
Reptiliomorpha
Reptiliomorpha refers to an order or subclass of reptile-like amphibians, which gave rise to the amniotes in the Carboniferous. Under phylogenetic nomenclature, the Reptiliomorpha includes their amniote descendants though, even in phylogenetic nomenclature, the name is mostly used when referring to...
, and Säve-Söderbergh's definition is more equivalent to Romer's suborder Embolomeri
Embolomeri
The Embolomeri is a suborder of Reptiliomorpha. The Embolomeri first evolved from reptile-like amphibians in the Early Carboniferous...
. This definition was also used by Edwin H. Colbert and Robert L. Carroll
Robert L. Carroll
Robert Lynn Carroll is a vertebrate paleontologist who specialises in Paleozoic and Mesozoic amphibians and reptiles.Carroll was an only child and grew up on a farm near Lansing, Michigan...
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. Michel Laurin
Michel Laurin
Michel Laurin is a Canadian vertebrate paleontologist specialising in the origin and phylogeny of tetrapods, comparative biology and paleobiology. As an undergraduate he worked in the laboratory of Robert L. Carroll, and took his doctor thesis on the osteology of seymouriamorphs under Robert R....
(1996) uses the term in a cladistic
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
sense to refer to only the most advanced reptile-like amphibians
Reptiliomorpha
Reptiliomorpha refers to an order or subclass of reptile-like amphibians, which gave rise to the amniotes in the Carboniferous. Under phylogenetic nomenclature, the Reptiliomorpha includes their amniote descendants though, even in phylogenetic nomenclature, the name is mostly used when referring to...
. Thus his definition include the (Diadectomorpha
Diadectomorpha
Diadectomorpha are a clade of large reptile-like amphibians that lived in Euramerica during the Carboniferous and Early Permian periods, and are very close to the ancestry of the Amniota. They include both large carnivorous and even larger herbivorous forms, some semi-aquatic and others fully...
and Solenodonsauridae) and the amniotes. However, Michael Benton
Michael J. Benton
Michael J. Benton is a British paleontologist, a Fellow of the Royal Society of Edinburgh, and professor of vertebrate palaeontology in the Department of Earth Sciences at the University of Bristol....
(2000, 2004) makes the anthracosaurs a paraphyletic order within the superorder Reptiliomorpha
Reptiliomorpha
Reptiliomorpha refers to an order or subclass of reptile-like amphibians, which gave rise to the amniotes in the Carboniferous. Under phylogenetic nomenclature, the Reptiliomorpha includes their amniote descendants though, even in phylogenetic nomenclature, the name is mostly used when referring to...
, along with the orders Seymouriamorpha
Seymouriamorpha
Seymouriamorpha were a small but widespread group of reptiliomorphs. Many seymouriamorphs were terrestrial or semi-aquatic. However, aquatic larvae bearing external gills and grooves from the lateral line system has been found, making them unquestionably amphibians. The adults were terrestrial...
and Diadectomorpha
Diadectomorpha
Diadectomorpha are a clade of large reptile-like amphibians that lived in Euramerica during the Carboniferous and Early Permian periods, and are very close to the ancestry of the Amniota. They include both large carnivorous and even larger herbivorous forms, some semi-aquatic and others fully...
, thus making the Anthracosaurians the "lower" reptile-like amphibians. In his definition, the group encompass the Embolomeri
Embolomeri
The Embolomeri is a suborder of Reptiliomorpha. The Embolomeri first evolved from reptile-like amphibians in the Early Carboniferous...
, Chroniosuchia
Chroniosuchia
The Chroniosuchia are a suborder or order of labyrinthodonts that lived in the middle Permian and the upper Triassic periods of Eastern Europe, Kyrgyzstan, China and Germany. They were all rather short limbed with a strong tail and elongated snout, somewhat resembling modern crocodiles...
and possibly the family Gephyrostegidae.
Etymology
The name "Anthracosauria" is GreekGreek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
('coal lizards'), because many of its fossils were found in the Coal Measures
Coal Measures
The Coal Measures is a lithostratigraphical term for the coal-bearing part of the Upper Carboniferous System. It represents the remains of fluvio-deltaic sediment, and consists mainly of clastic rocks interstratified with the beds of coal...
.