Macropalaeontology of the Trochocyathus-Trematotrochus band (Paleocene/Eocene boundary), Dilwyn Formation, Otway Basin, Victoria

Abstract

Our limited knowledge of latest Paleocene and earliest Eocene Australian macrofaunas is much reduced with the report here of 37 species of invertebrates and vertebrates from coastal outcrops of the Dilwyn Formation in the Otway National Park, Victoria. The Trochocyathus-Trematotrochus band in the lowermost part of the Dilwyn Formation has yielded the highest taxonomic diversity in the formation, with 29 species of shallow marine bivalves, gastropods and scaphopods, along with less common brachiopods, echinoderms and cnidarians, and sparse vertebrate remains (shark teeth, otoliths). At least seven (possibly ten) molluscan species are common to the underlying Pebble Point Formation. Four new species are the gastropods Drepanocheilus (Tulochilus) retisurus sp. nov., Cerithiella leptopyrga sp. nov., Volutomitra (Waimatea) dilwyni sp. nov. and Mauidrillia otwayensis sp. nov. Eight probably new taxa are: Euspira? sp. nov., Nassaria? sp. nov., Odostomia? sp. nov.?, Circulus sp. nov.?, Proximitra sp. nov. cf. P. trirugulata Darragh, 1997, Microvoluta? sp. nov., Dentalium? sp. nov.? and Trematotrochus sp. nov. All macroinvertebrate species are, on present knowledge, endemic to Victoria, with the exception of Parvamussium sp. which is known from Western Australia.