''Branchiosaurus'' (from el, βράγχιον , 'gill' and el, σαῦρος , 'lizard') 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 ...

of small, lightly built early

prehistoric amphibian This list of prehistoric amphibians is an attempt to create a comprehensive listing of all Genus, genera from the fossil record that have ever been considered to be amphibians, excluding purely vernacular terms. The list includes all commonly accep ...

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s have been discovered in strata dating from the late Pennsylvanian Epoch to 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 ...

Period. The taxa may be invalid; the material referred to the genus may be juvenile specimens of larger amphibians. Branchiosaurus BW

This tiny amphibian was very similar to the Rachitomi, differing primarily in size. Other distinguishing characteristics include a cartilaginous, less ossified skeleton and a shorter skull. Clear traces of

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

s are present in many fossilized samples, hence the name. Originally thought to have

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...

distinct from rachitomous vertebrae, it was placed in a separate order named Phyllospondyli ("leaf vertebrae"). Later analysis of growth stages showed increasing ossification in larger specimens, which showed that at least some of the species was the

larval stage A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

of much larger rachitomes like ''

Eryops ''Eryops'' (; from Greek , , 'drawn-out' + , , 'face', because most of its skull was in front of its eyes) is a genus of extinct, amphibious temnospondyls. It contains the single species , the fossils of which are found mainly in early Permian (a ...

'', while others represent

paedomorphic Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compared ...

species which retained the larval gills in adulthood.Boy, J.A. (1972): Die Branchiosaurier (Amphibia) des saarpfalzichen Rotliegenden (Perm, SW-Deutschland). ''Abhandlungen des Hessische Landesamt, Bodenforschung'' No 65, pp 1-137 Distribution is uncertain, though available fossils come from central Europe, most famous of which are the Permian Niederkirchen Beds around Pfalz, Germany.

References

External links

Fossil picture.''Branchiosaurus at BioLib.cz''
Branchiosaurids Permian temnospondyls of Europe Prehistoric amphibian genera {{Permian-animal-stub