Eocene molluscs from the Merlinleigh Sandstone, Carnarvon Basin, Western Australia

WA Museum Records and Supplements | Updated 7 years ago

ABSTRACT – Sixteen species of molluscs are described from the Late Eocene Merlinleigh Sandstone, Carnarvon Basin, Western Australia. The assemblage, a random thanatocoenose, is dominated by bivalves (11 species) and a cephalopod, with a few gastropod specimens. All primary shell carbonate — calcite or aragonite — is replaced by silica. The assemblage is distinctive in composition, resembling no other known from the Australian Eocene. Terrestrial plant material, all silicifi ed, is associated with the marine fossils, consistent with a depositional environment of the energised sandy littoral, subject to river fl ood discharge. At a height of +280 to 300 m AHD, the formation compares closely with others of similar age in southwestern Australia, which also consist of a combination of marine and terrestrial fossil material. Faunal affinities with the southern Australian Eocene were weak; an apparent Tethyan-Indo-Southwest Pacific inf uence is present, possibly with a weak endemic element. The taxonomy of the nautiloid Aturia clarkei is discussed.

KEYWORDS: new species, fossils, Tethyan-Indo-Southwest Pacific influence, silicification, Aturia.