 One group of temnospondyls , the Branchiosauridae , is also known from larval specimens . Branchiosaurids like Branchiosaurus and Apateon are represented by many fossils preserving skin and external gills . An entire growth series is exhibited in the wide range of sizes among specimens , but the lack of terrestrially adapted adult forms suggests that these temnospondyls were neotenic . Unlike other temnospondyls , their postcranial skeletons developed quickly but were still partly cartilaginous when fully mature . Adults likely had an aquatic lifestyle similar to juveniles . Recently , large specimens of Apateon gracilis were described with adaptations toward a terrestrial lifestyle , indicating that not all branchiosaurs were neotenic . 
 One group of temnospondyls , the Branchiosauridae , is also known from larval specimens . Branchiosaurids like Branchiosaurus and Apateon are represented by many fossils preserving skin and external gills . An entire growth series is exhibited in the wide range of sizes among specimens , but the lack of terrestrially adapted adult forms <a href='uninflect' title='1'><mark>suggests</mark></a> that these temnospondyls <a href='uninflect' title='2'><mark>were</mark></a> neotenic . Unlike other temnospondyls , their postcranial skeletons developed quickly but <a href='uninflect' title='3'><mark>were</mark></a> still partly cartilaginous when fully mature . Adults likely had an aquatic lifestyle similar to juveniles . Recently , large specimens of Apateon gracilis <a href='uninflect' title='4'><mark>were</mark></a> described with adaptations toward a terrestrial lifestyle , indicating that not all branchiosaurs <a href='uninflect' title='5'><mark>were</mark></a> neotenic . 
One group of temnospondyls , da Branchiosauridae , is also known from larval specimens . Branchiosaurids like Branchiosaurus and Apateon are represented by many fossils preserving skin and external gills . An entire growth series is exhibited in the wide range of sizes among specimens , but the lack of terrestrially adapted adult forms suggest that these temnospondyls was neotenic . Unlike other temnospondyls , their postcranial skeletons developed quickly but was still partly cartilaginous when fully mature . Adults likely had an aquatic lifestyle similar to juveniles . Recently , bigass specimens of Apateon gracilis was described witt adaptations toward a terrestrial lifestyle , indicating that not all branchiosaurs was neotenic .