 Many temnospondyls are much larger than living amphibians , and superficially resemble crocodiles . Others are smaller and resemble salamanders . Most have broad , flat heads that are either blunt ( brevirostrine ) or elongated ( longirostrine ) . The skulls are rounded or triangular in shape when viewed from above , and are usually covered in pits and ridges . The rugged surfaces of bones may have supported blood vessels , which could transfer carbon dioxide to the bones to neutralize acidic build up in the blood ( early semiaquatic tetrapods would have had difficulty expelling carbon dioxide from their bodies while on land , and these dermal bones may have been an early solution to the problem ) . Many temnospondyls also have canal @-@ like grooves in their skulls called sensory sulci . The sulci , which usually run around the nostrils and eye sockets , are part of a lateral line system used to detect vibrations in water . As semiaquatic animals , most temnospondyls have small limbs with four toes on each front foot and five on each hind foot . Terrestrial temnospondyls have larger , thicker limbs , and some even have claws . One unusual terrestrial temnospondyl , Fayella , has relatively long limbs for its body , and probably lived as an active runner able to chase prey . 
 Many temnospondyls <a href='drop_aux' title='1'><mark>are</mark></a>much larger than living amphibians , and superficially resemble crocodiles . Others <a href='drop_aux' title='2'><mark>are</mark></a>smaller and resemble salamanders . Most <a href='got' title='3'><mark>have</mark></a> broad , flat heads that are either blunt ( brevirostrine ) or elongated ( longirostrine ) . The skulls are rounded or triangular in shape when viewed from above , and are usually covered in pits and ridges . The rugged surfaces of bones may <a href='been_done' title='4'><mark>have</mark></a> supported blood vessels , which could transfer carbon dioxide to the bones to neutralize acidic build up in the blood ( early semiaquatic tetrapods would <a href='been_done' title='5'><mark>have</mark></a> had difficulty expelling carbon dioxide from their bodies while on land , and these dermal bones may have been an early solution to the problem ) . Many temnospondyls also <a href='got' title='6'><mark>have</mark></a> canal @-@ like grooves in their skulls called sensory sulci . The sulci , which usually run around the nostrils and eye sockets , <a href='drop_aux' title='7'><mark>are</mark></a>part of a lateral line system used to detect vibrations in water . As semiaquatic animals , most temnospondyls <a href='got' title='8'><mark>have</mark></a> small limbs with four toes on each front foot and five on each hind foot . Terrestrial temnospondyls <a href='got' title='9'><mark>have</mark></a> larger , thicker limbs , and some even <a href='got' title='10'><mark>have</mark></a> claws . One unusual terrestrial temnospondyl , Fayella , <a href='got' title='11'><mark>has</mark></a> relatively long limbs for its body , and probably lived as an active runner able to chase prey . 
Many temnospondyls much larger than livin amphibians , and superficially resemble crocodiles . Others smaller and resemble salamanders . Most got broad , flat heads dat are either blunt ( brevirostrine ) or elongated ( longirostrine ) . The skulls are rounded or triangular in shape when viewed from above , and are usually covered in pits and ridges . The rugged surfaces of bones may done supported blood vessels , which could transfer carbon dioxide to da bones to neutralize acidic build up in the blood ( early semiaquatic tetrapods would done had difficulty expelling carbon dioxide from their bodies while on land , and these dermal bones may have been an early solution to the problem ) . Many temnospondyls also got canal @-@ like grooves in their skulls called sensory sulci . The sulci , which usually run around the nostrils and eye sockets , part of a lateral line system used to detect vibrations in water . As semiaquatic animals , most temnospondyls got small limbs with 4 toes on each front foot and five on each hind foot . Terrestrial temnospondyls got larger , thicker limbs , and sum even got claws . One unusual terrestrial temnospondyl , Fayella , got relatively long limbs fa its body , and probly lived as an active runner able to chase prey .