The lissamphibian humerus and elbow joint, and the origins of modern amphibians

摘要: The origins and evolution of the three major clades modern amphibians are still a source controversy, no general consensus exists as to their relationship various known Paleozoic taxa. This may indicate that additional character complexes should be studied resolve phylogenetic relationship. salamander elbow joint has been fundamentally misinterpreted in previous morphological descriptions. In caudates anurans, both radius ulna (fused anurans) articulate with characteristically large capitulum (radial condyle), although part ulnar articulating surface fits into smooth trochlear region. "ulnar condyle" descriptions is fact entepicondyle. condition seen batrachians (i.e., salamanders frogs) lissamphibian synapomorphy because region primitive fossil caecilian Eocaecilia resembles those frogs salamanders. addition bulbous capitulum, all humeri lack an entepicondylar foramen, possess distally pointing entepicondyle, low rounded ectepicondyle, elongated shaft. These characters identified key forms assess support for different hypotheses proposed evolutionary lissamphibians. Temnospondyli only group early tetrapods shows progressive traits humerus joint. Furthermore, among taxa, dissorophoid temnospondyl Doleserpeton annectens taxon full set humeral features shared by results add theory monophyletic origin lissamphibians from dissorophoidtemnospondyls.