By the end of the 19th century , most of what are today regarded as temnospondyls were placed in the suborder Labyrinthodonta . American paleontologist Ermine Cowles Case called it Labyrinthodonta vera or " true labyrinthodonts " . The names Stegocephalia and Labyrinthodontia were used interchangeably to refer to the order in which it belonged . The labyrinthodontian suborders Microsauria and Branchiosauria , both of which contain temnospondyls , were distinct from Labyrinthodonta . Within Labyrinthodonta were the groups Rhachitomi , Labyrinthodonti , and Embolerimi . Members of Rhachitomi , such as Archegosaurus and Eryops , had rhachitomous vertebrae with enlarged intercentra that displaced the pleurocentra . Labyrinthodonti , such as Mastodonsaurus , Trematosaurus , and Micropholis , had lost their pleurocentra , and the intercentra made up the entire body of the vertebrae . Embolerimi had intercentra and pleurocentra that were of equal size . Embolomeres are now identified as reptiliomorphs distantly related to temnospondyls .