Many changes in the sensory systems of tetrapods are associated
with the water-to-land transition. In hearing, one of the
crucial elements in detecting airborne sound is the tympanic
ear. Surprisingly, the tympanic ear originated independently in
the major tetrapod lineages and relatively late after the
terrestrial tetrapods emerged – in the Triassic, more than 100
million years after the origin of tetrapods. The major question
raised by the researchers Jakob Christensen-Dalsgaard, Christian
Brandt and Magnus Wahlberg, University of Southern Denmark, and
Maria Wilson and Peter T. Madsen, Aarhus University was what
hearing was like in the early tetrapods before the origin of the
tympanic ear. To answer that question the research group
measured hearing in the closest living relative of tetrapods,
the lungfish. The scientists measured evoked potentials in the
brain of lightly anesthetized African lungfish in response to
airborne and underwater sound and to vibrations of the head. The
vibration sensitivity of lun