''Archegosaurus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order (biology), order of small to giant tetrapods—often considered Labyrinthodontia, primitive amphi ...

amphibian Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...

which lived during the

Asselian In the geologic timescale, the Asselian is the earliest geochronologic age or lowermost chronostratigraphic stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Asselian lasted between and million years ago (Ma). It ...

Wuchiapingian In the geologic timescale, the Wuchiapingian or Wujiapingian (from in the Liangshan area of Hanzhong, Shaanxi Province) is an age or stage of the Permian. It is also the lower or earlier of two subdivisions of the Lopingian Epoch or Series. The ...

stages of the

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...

, around 299-253 million years ago. The remains of this animal, consisting of at least 90 partial skeletons (mostly skulls), have been found in

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

. The name ''Archegosaurus'' was coined by Goldfuss in 1847. ''Archegosaurus'' is a member of

Archegosauridae Archegosauridae is a family of relatively large and long snouted temnospondyls that lived in the Permian period. They were fully aquatic animals, and were metabolically and physiologically more similar to fish than modern amphibians.Florian Witzm ...

and is that

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal f ...

Classification

In 1938, paleontologist Margaret C. Steen described a temnospondyl from the Permian-age Ruprechtice assemblage in northeast

Bohemia Bohemia ( ; cs, Čechy ; ; hsb, Čěska; szl, Czechy) is the westernmost and largest historical region of the Czech Republic. Bohemia can also refer to a wider area consisting of the historical Lands of the Bohemian Crown ruled by the Bohem ...

. Steen named it ''Memonomenos dyscriton'' on the basis of a skull that was narrower than others in the Ruprechtice. It was classified as an

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

, a group closely related to reptiles. Both ''Memonomenos'' and

embolomere Embolomeri is an Order (biology), order of Tetrapod, tetrapods or Stem-group, stem-tetrapods, possibly members of Reptiliomorpha. Embolomeres first evolution, evolved in the Early Carboniferous (Mississippian age, Mississippian) Period and were th ...

anthracosaurs had vertebrae that were divided into several parts, including a pleurocentrum and intercentrum. Animals with this type of divided vertebrae were said to be

rachitomi The Rachitomi were a group of extinct Palaeozoic labyrinthodont amphibians, according to an earlier classification system.Kent, G.C. & Miller, L. (1997): Comparative anatomy of the vertebrates. 8th edition. Wm. C. Brown Publishers. Dubuque. 487 p ...

. During the early twentieth century, paleontologists considered rhachitomous temnospondyls to be the descendants of embolomeres, and Steen considered ''Memonomenos'' to be a link between these two groups. Steen also noted that ''Memonomenos'' had large

tabular Table may refer to: * Table (furniture), a piece of furniture with a flat surface and one or more legs * Table (landform), a flat area of land * Table (information), a data arrangement with rows and columns * Table (database), how the table data ...

horns, a feature shared with anthracosaurs. Temnospondyls and anthracosaurs were later found to be two distantly related groups, and paleontologist

Alfred Romer Alfred Sherwood Romer (December 28, 1894 – November 5, 1973) was an American paleontologist and biologist and a specialist in vertebrate evolution. Biography Alfred Romer was born in White Plains, New York, the son of Harry Houston Romer an ...

placed ''Memonomenos'' within Anthracosauria. This placement was accepted until 1978 when ''Memonomenos'' was reassigned to the genus ''Archegosaurus'' and classified as a temnospondyl. ''Memonomenos dyscriton'' became a second species of ''Archegosaurus'', ''A. dyscriton''.

Biology

Water balance of the Archegosaurus model

''Archegosaurus'' was a fully aquatic animal. A study regarding its metabolism, gas exchange, osmoregulation, and digestion suggest that it was rather similar to

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

, rather than modern aquatic amphibians like salamanders.Florian Witzmann; Elizabeth Brainerd (2017). "Modeling the physiology of the aquatic temnospondyl Archegosaurus decheni from the early Permian of Germany". Fossil Record. 20 (2): 105–127. doi:10.5194/fr-20-105-2017.

References

* Witzmann, Florian and Scholz, Henning (2006)
"Morphometric study of allometric skull growth in the temnospondyl ''Archegosaurus decheni'' from the Permian/Carboniferous of Germany"
''Geobios'' 40: 4, pp 541–554.

External links

from Palaeos.com {{Taxonbar, from=Q748733 Permian temnospondyls of Europe Stereospondylomorphs Fossil taxa described in 1847 Prehistoric amphibian genera Taxa named by Georg August Goldfuss