Tetrapod-like middle ear architecture in a Devonian fish

Detailed study of Panderichthys, a lobe-finned fish closely related to the first amphibians, suggests that the early stages in the evolution of the vertebrate middle ear were related to breathing, rather than detecting sound. Our middle ear corresponds to a reduced gill slit called the ‘spiracle’ in fishes. In a well preserved Panderichthys fossil specimen held in the Latvian Natural History Museum in Riga, this gill slit is much larger than in other ancient fish species and has vertebrate-like architecture, yet was probably used to inhale water or air. It seems that a rudimentary auditory role for the stapes and other middle-ear components first developed in primitive land vertebrates.