Cenozoic Molluscs and Echinoids of Barrow Island, Western Australia

WA Museum Records and Supplements | Updated 9 years ago

Abstract - A survey of the Cenozoic fossil fauna of Barrow Island, northwest Australia, has yielded a rich fauna of Middle Miocene and Late Pleistocene molluscs, and a rich Middle Miocene echinoid fauna. This paper, in recording 179 species, represents the first documentation of the fossil fauna of Barrow Island. The Miocene limestones reach up to 29 m in thickness in cliff sections exposed on the western side of the island. On the eastern side they are up to 9 m thick and are overlain by Late Pleistocene limestones. Formerly considered to belong to the Trealla Limestone, the Miocene limestones are regarded as a distinct formation, herein termed the "Poivre Formation", on account of their more variable and generally coarser sediment grain size.

The Poivre Formation yielded 270 specimens, comprising 70 species of bivalves and gastropods, 9 species of echinoids, plus indeterminate species of cephalopod, calcareous worm and corals. The Late Pleistocene fauna from an unnamed formation consists of 83 species of bivalves and gastropods, 11 species of corals and a single species of crustacean. Formal descriptions are given of the Miocene bivalves, gastropods and echinoids. New species of naticid gastropod, Ampullina butleri sp. nov., toxopneustid echinoid, Tripneustes pregratilla sp. nov., clypeasterid echinoid Clypeaster tumulus sp. nov. and echinolampadid echinoid Echinolampas butleri sp. nov., are described.

The Miocene mollusc and echinoid fauna has little in common with contemporaneous faunas from the Nullarbor Limestone in the Eucla Basin. The echinoid fauna shows more in common with Miocene faunas of Java and India, than it does with Miocene echinoids of southern Australia.The mollusc and echinoid faunas show strong affinities with modern communities.