 By the end of the 19th century , most of what are today regarded as <unk> were placed in the suborder <unk> . American paleontologist Ermine Cowles Case called it <unk> vera or " true <unk> " . The names <unk> and Labyrinthodontia were used interchangeably to refer to the order in which it belonged . The <unk> suborders <unk> and <unk> , both of which contain <unk> , were distinct from <unk> . Within <unk> were the groups <unk> , <unk> , and <unk> . Members of <unk> , such as <unk> and <unk> , had <unk> vertebrae with enlarged <unk> that displaced the <unk> . <unk> , such as Mastodonsaurus , <unk> , and <unk> , had lost their <unk> , and the <unk> made up the entire body of the vertebrae . <unk> had <unk> and <unk> that were of equal size . <unk> are now identified as <unk> distantly related to <unk> . 
