''Plagiosaurus'' is an extinct genus of temnospondyl amphibian - Arthur Smith Woodward regarded it as a synonym of ''

Plagiosternum ''Plagiosternum'' (plae-jee-oh-ster-num, meaning "sideways breastbone") was a middle Triassic temnospondyl that is native to Spitzbergen Svalbard ( , ), also known as Spitsbergen, or Spitzbergen, is a Norwegian archipelago in the Ar ...

''. They were paedomorphic, retaining the larval

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 ar ...

s on adulthood. They had weak simplified

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 characteristi ...

, consisting of large intercentra and

neural arch 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 ...

es, the

stereospondyl The Stereospondyli are a group of extinct temnospondyl amphibians that existed primarily during the Mesozoic period. They are known from all seven continents and were common components of many Triassic ecosystems, likely filling a similar ecologi ...

condition.

References

Triassic temnospondyls of Europe Plagiosauridae {{temnospondyli-stub