A 6000 Year‐old Fossil Dugong from Botany Bay: Inferences about Changes in Sydney's Climate, Sea Levels and Waterways

Abstract

The excavation in the 1890s of a skeleton of the warm-water marine mammal Dugong dugon , associated with Aboriginal artefacts, from a Botany Bay salt marsh, marked the beginning of speculation about climate and sea level change in Australia over the period of human occupation. The dugong bones have recently been dated, giving a conventional 14 C age of 5520 ± 70 years BP, which is consistent with three older 14 C dates for a layer of buried trees that underlies much of the north Botany sediments. The carefully drawn cross-sections of depositional strata produced by the original discoverers allow further interpretation of the pattern of Holocene sea-level fluctuations in the Sydney region. Layers of estuarine sediment, such as the one containing the dugong skeleton, are inter-bedded with peat layers containing in situ roots and stumps, suggesting that the site alternated between sub-aerial exposure and submergence throughout the Holocene. The presence of the dugong is suggestive of warmer conditions, and its inland location indicates a more extensive Botany Bay in the recent past. This is in agreement with other work from southern New South Wales describing both warm-water marine species and higher sea levels several thousand years ago.

A deep dive into the ecology of Gamay (Botany Bay, Australia): current knowledge and future priorities for this highly modified coastal waterway

“…Rarer sightings of larger fish such as whale shark (Rhincodon typus) and bump-head sunfish (Mola alexandrine) have also been reported in Gamay. Bones of Dugong excavated from an indigenous midden near Gamay suggest that dugongs occurred in the area historically (Haworth et al 2004); however, recent sightings along the NSW coast are rare and none has been reported in Gamay (Allen et al 2004). Little penguins (Eudyptula minor) can also occasionally be seen foraging for baitfish in Gamay (Carter 2020).…”