The Otic notch is another feature shared between modern amphibians and
the temnospondyls. The otic notch is an area at the back of the skull
where a stapes has been found in come individuals. In modern amphibia
it comprises part of the ear and it is suggested that the Lissamphibian
ear originated in the Temnospondyli and evolved from there.
Bicuspid teeth are found in almost all modern amphibia. Those that
don't have bicuspid teeth generally have a variation on it, i.e.
tricuspid or monocuspid. These variations are said to have evolved
after the divergence of the groups. Some early temnospondyls, e.g. Dolserpeton
, appear to have bicuspid teeth as well as a number of other characteristics found in the Lissamphibia.
shows a bicuspid tooth in section.
All these characters as well as more anotomically specific characters
have been found in certain individual specimens or species of
lepospondyl. This has brought about a conclusion that the lepospondyls
are the ancestors of the modern amphibia and that the temnospondyls did
not give rise to any further groups. Whether or not this is the correct
conclusion or whether the temnospondyl origin of the lissamphibia is
correct is the subject of a strongly contested debate.