 Temnospondyli ( from Greek τέμνειν ( temnein , " to cut " ) and σπόνδυλος ( spondylos , " vertebra " ) ) is a diverse subclass of extinct small to giant tetrapods — often considered primitive amphibians — that flourished worldwide during the Carboniferous , Permian , and Triassic periods . A few species continued into the Cretaceous . Fossils have been found on every continent . During about 210 million years of evolutionary history , they adapted to a wide range of habitats , including fresh water , terrestrial , and even coastal marine environments . Their life history is well understood , with fossils known from the larval stage , metamorphosis , and maturity . Most temnospondyls were semiaquatic , although some were almost fully terrestrial , returning to the water only to breed . These temnospondyls were some of the first vertebrates fully adapted to life on land . Although temnospondyls are considered amphibians , many had characteristics , such as scales , claws , and armour @-@ like bony plates , that distinguish them from modern amphibians . 
 Temnospondyli ( from Greek τέμνειν ( temnein , " to cut " ) and σπόνδυλος ( spondylos , " vertebra " ) ) <a href='drop_aux' title='1'><mark>is</mark></a>a diverse subclass of extinct small to giant tetrapods — often considered primitive amphibians — that flourished worldwide during the Carboniferous , Permian , and Triassic periods . A few species continued into the Cretaceous . Fossils <a href='been_done' title='2'><mark>have</mark></a> been found on every continent . During about 210 million years of evolutionary history , they adapted to a wide range of habitats , including fresh water , terrestrial , and even coastal marine environments . Their life history is well understood , with fossils known from the larval stage , metamorphosis , and maturity . Most temnospondyls <a href='uninflect' title='3'><mark>were</mark></a> semiaquatic , although some <a href='uninflect' title='4'><mark>were</mark></a> almost fully terrestrial , returning to the water only to breed . These temnospondyls <a href='uninflect' title='5'><mark>were</mark></a> some of the first vertebrates fully adapted to life on land . Although temnospondyls are considered amphibians , many had characteristics , such as scales , claws , and armour @-@ like bony plates , <a href='null_relcl' title='6'><mark>that</mark></a>distinguish them from modern amphibians . 
Temnospondyli ( from Greek τέμνειν ( temnein , " to cut " ) and σπόνδυλος ( spondylos , " vertebra " ) ) a diverse subclass of extinct small to giant tetrapods — often considered primitive amphibians — that flourished worldwide during the Carboniferous , Permian , and Triassic periods . A few species continued into da Cretaceous . Fossils done been found on every continent . durin bou 210 million yrs of evolutionary history , they adapted to a wide range of habitats , including fresh water , terrestrial , and even coastal marine environments . Their life history is well understood , with fossils known from tdalarval stage , metamorphosis , and maturity . Most temnospondyls was semiaquatic , although sum was almost fully terrestrial , returning to thdaater only to breed . dem temnospondyls was some of thedarst vertebrates fully adapted to life on land . Although temnospondyls r considered amphibians , many had characteristics , such as scales , claws , and armour @-@ like bony plates , distinguish em from modern amphibians .