Figure A shows the skull of a Palaeogyrinus.
The illustration clearly shows an area at the back of the skull that
looks like a large chunk has been taken out. This is the Otic Notch.
Figure B shows the skull of a Parotosuchus.
On the left hand side of the skull toward the back you can see two
holes. These are the otic notches, however in this species they are
almost closed off.
In some specimens scientists have found a stapes, the same bone found
in our own ear. Some experts suggest that the Otic notch had a tympanum
(similar to our ear drum) stretched across it. However others disagree
and show that the stapes bones found in the fossil were too thick and
robust in early temnospondyls to be of any use for hearing. Whether or
not it appeared in later temnopondyls is not certain. While it is
accepted that the ear probably did arise from strucutres similar to
these, temnospondyls probably did not have ears per se.
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