Unlocking archives of faunal dispersal in rock deposits: the key to reconstructing palaeoenvironmental change and human dispersal in Southeast Asia
Chief Investigators for this 3-year Australian Discovery Project (2010-2012) are Kira Westaway (Macquarie University), Mike Morwood and Gert van den Bergh, who aim to provide critical new insights into the timing of faunal dispersals and widespread environmental changes in southern China and Southeast Asia over the last 500,000 years.
Locations of published breccia sites containing fossils in southern China and Southeast Asia.
Rainforest animals represented in the Punung breccias, East Java. The deposits are of early Last Interglacial age (~125 ka).
In the past, open environments prevailed during drier glacial periods, while rainforests expanded during warmer, wetter interglacials. Such climatic changes were associated with faunal migrations, replacements and extinctions. Despite the significance of these events, their timing is uncertain because a lack of dating applications, which has meant that the ages of many of the key fossil sites are not known.
This project aims to rectify this situation by using luminescence and U-series dating to determine the age of cave breccias containing faunal remains. Breccia deposits are cemented accumulations in caves and are generally preserved against the walls. Under wet conditions, the deposits become cemented by calcite (secondary limestone deposits), combine with other cave sediments, and form a hard breccia that is more resistant to erosion than softer cave sediments.
During periods of rainforest expansion, porcupines were one of the main contributors to the profusion of fossils found in Southeast Asian bone breccia deposits. These animals collect bones and teeth from the landscape and store them in their ‘lairs’ (caves), where they can become incorporated and cemented into breccias. Such ‘scavenged bone accumulations’ reflect the range of animals found in the surrounding landscape and occur within dateable deposits. They provide crucial evidence for faunal sequences and evolution in Southeast Asia.
Westaway, K.E., Morwood, M.J., Roberts, R., Rokus, A.D., Zhao, J.-x., Storm, P., Aziz, F., van den Bergh, G.D., Hadi, P., Jatmiko, & de Vos, J. (2007).Age and biostratigraphic significance of the Punung Rainforest Fauna, East Java, Indonesia, and implications for Pongo and Homo. Journal of Human Evolution 2007, 53, 709-717.