LAUSR

ABSTRACT Lungfish tooth plates have been known from Cretaceous deposits at Lightning Ridge and nearby opal fields since 1914. These specimens are reasonably complete, and assigned to a common Mesozoic genus, Metaceratodus wollastoni. Later, several small fragments of lungfish tooth plates collected in 1981 were described as indistinguishable from tooth plates of the living Australian lungfish, Neoceratodus forsteri. However, new dental material has since been collected, consisting of tooth plates with attached bone from both jaws, and this has prompted a revision of the original determination. A new species of lungfish, Neoceratodus potkooroki, can be erected, based on characters of both the tooth plates and the jaw bones, and N. forsteri can no longer be considered a Cretaceous taxon. The oldest occurrence of N. forsteri is now considered to be Pliocene, in the Chinchilla Sands from Chinchilla in Queensland. Material of two other species of dipnoan, M. wollastoni and Ceratodus diutinus, have since been collected from the Cretaceous Griman Creek Formation, and both are easily distinguished from the new species of Neoceratodus.