Kesteven, (1951), was convinced that the Dipnoi were the
ancestors of amphibians.
To prove his theory, he wrote up a list of around 40 shared
characteristics between them and the first true terrestrial vertebrates.
This is a technique that is common when trying to prove
Some of the characteristics he quoted were:
Structure and position of the glottis
possesion on an epiglotis
Kesteven went on to say that the lungfish, (a type of
Dipnoi), were the closest relatives of tetrapods and that no fossil group
lay between them.