Practice question

Amphibians share most recent common ancestor with lungfishes within Sarcopterygii lobe-finned clade, more closely related than to actinopterygian ray-finned fishes, reptiles, birds or mammals which are nested crown tetrapods. Shared derived characters include internal choanae connecting nasal cavity to mouth, fleshy pectoral fins with single basal element homologous to humerus, pulmonary respiration, similar neurocranial structure and tooth enamel. Molecular phylogenies concatenate nuclear and mitochondrial genes placing Dipnoi sister to Tetrapoda, supported by transitional fossils like Tiktaalik and Panderichthys bridging gap, lungfishes therefore closest living fish relatives.