The study of fossil and extant dipnoan dentitions shows that the shagr
een of denticles found in such Devonian genera as Uranolophus and Crip
hognathus is not primitive for the group, that the ontogeny of the ext
ant Neoceratodus is not a guide to the primitive adult tooth plate, th
at homology between teeth on dipnoan tooth plates and polyphyodont mar
ginal teeth of other osteichthyans has not been established, and that
the Chinese Devonian genus Diabolepis should nor be regarded as a dipn
oan. We conclude that no convincing argument has been advanced to dest
roy our contention that the primitive dipnoan plate was a relatively f
eatureless sheet that was added to at the margins by the incorporation
of small enamel-covered dentine blisters, and was thickened by resorp
tion of the basal bone and subsequent ingrowth by pleromic dentine.