Sharks from the mid-Cretaceous Gearle Siltstone, Southern Carnarvon Basin, Western Australia

ABSTRACT

A small but diverse selachian fauna, represented by isolated teeth, is described from the lower part of the Gearle Siltstone in the Giralia Anticline, Southern Carnarvon Basin, Western Australia. It consists of: Notorynchus aptiensis, Paraorthacodus sp., Orectolobiformes gen. et sp. nov., Archaeolamna sp., Leptostyrax sp., Cretoxyrhinidae gen. et sp. incertae sedis, Cretolamna sp., Paraisurus aff. compressus, Carcharias striatula, and Squalicorax primaevus. Comparisons with known ranges of these taxa in the Northern Hemisphere place the fauna in the middle to late Albian. Contrary to previous claims, the cowshark Notorynchus aptiensis does not appear to have been primarily a Tethyan faunal element, as its teeth are more common in the cool water facies of the Gearle Siltstone than anywhere else in the world. The few previous records of Cretaceous sharks from Western Australia are revised, resulting in several systematic alterations.