Later in the 19th century , temnospondyls were classified as various members of Stegocephalia , a name coined by American paleontologist Edward Drinker Cope in 1868 . Cope placed stegocephalians in the class Batrachia , the name then used for Amphibia . Stegocephalia means " roof @-@ headed " in Greek , a reference to the wide , flat heads of temnospondyls and other early tetrapods . During this time , palaeontologists considered temnospondyls to be amphibians because they possessed three main features : gill arches in juvenile skeletons , indicating they were amphibious for at least the first part of their lives ; ribs that do not connect at the underside of the rib cage ; and deep pits in the skull that were interpreted as space for mucous glands .