An international team of researchers has found evidence that the human middle ear evolved from gills.
The human middle ear contains three vibratingbones that are involved in the transmission of air vibrations. It was assumed that this organ developed from a spiracle - a gill opening that has been preserved in some modern fish. In early vertebrates, they were searched for between the lower jaw and the hyoid arch, but could not be found.
Now scientists have studied fossil armoredgaleaspids from China and found spiracles in them. That is, the hypothesis was confirmed. As evolution progressed, many land-dwelling species shed their spiracles to breathe through their mouths and noses. And the spiracle could first develop into an auditory notch, and then into the ear.