An asterolepidoid antiarch (placoderm fish) from the Early Devonian of the Georgina Basin, central Australia

Abstract

A small collection of well-preserved antiarch remains from the basal calcareous unit of the Cravens Peak Beds is described and figured. This represents the earliest record of antiarchs from the Australian continent. An Emsian age, based on correlations with the Mulga Downs Group in the Darling Basin, makes this the earliest recorded antiarch occurrence outside of the south China province. All specimens are of small size and may be juvenile. Some resemblances to Pterichthyodes are noted, but the material is insufficient for formal taxonomic treatment. The structure of the asterolepidoid pectoral fin is discussed, and it is concluded that this is a shared primitive feature of euantiarchs generally. It is suggested that the primary distribution of asterolepidoid antiarchs did not include south China, and some implications of a vicariance explanation for the origin of bothriolepidoids in south China, and of asterolepidoids elsewhere, are briefly considered.