Avian Barometers Come from Fish

The paratympanic organ (PTO) in the middle ear of birds, commonly referred to as their natural barometer, apparently evolved from the sense organs of very ancient fish, investigators from the University of Cambridge established in a new study.

The ancient sense organ was originally found in aquatic creatures such as sharks and sturgeons, the team explains in a paper published in the latest issue of the scientific journal Nature Communications.

Scientists argue that the original function of the organ was to detect jaw movements. Later, as the first animals started walking on land, numerous organs that their ancestors had changed function, or disappeared entirely.

“It is not clear why the PTO was lost in the other amniote lineages – mammals, turtles, lizards and snakes – but the PTO’s function is likely to have been modified in birds for detecting air pressure during flight,” the research group explains.