Paleontological, Pleistocene, mammal, Naracoorte Caves, fossil record, taxonomy, pitfall, palaeocommunity

Abstract

The Naracoorte Caves World Heritage Area (NCWHA) in southern Australia preserves an almost continuous fossil record of the last 500,000 years but contains a noticeable temporal gap between ~100 ka and ~200 ka. This study presents the first comprehensive assessment of a fossil assemblage from the Naracoorte region from this “gap”. Fossils analysed in this study were excavated from Specimen Cave by the author, in the first documented palaeontological excavation of this cave. Preliminary dating from previous studies gives Specimen Cave an age of ~130 ka, placing it within the missing gap. The Specimen Cave fossil assemblage preserves a rich and diverse fauna which, shares many similarities with other NCWHA deposits. The deposit is dominated by small mammals, which constitute >90% of the fauna. The most abundant family in the deposit was Muridae (rodents), which also has the greatest species richness and density of all families. The large mammal fauna, which constitutes a very minor (<10%) component of the assemblage, is dominated by Macropodidae (kangaroos). The overall fauna is indicative of a woodland or open forest habitat, and this is the most likely vegetation to have existed in the proximal palaeoenvironment of the cave. The most likely mode of accumulation of the deposit is a pitfall trap, indicated by the presence of large mammals and the dominance of saltatory species in the large mammal fauna. The presence of megafauna such as Procoptodon sp. cf. P. goliah, provide the first robust evidence that some species of this large mammal group did not experience localised extinctions during this period. Comparisons to other mid Pleistocene NCWHA deposits reveal Specimen Cave has lower species richness than deposits older than 200 ka and younger than 100 ka. This apparent loss of richness is primarily attributed to the study’s limited sample size.