Dr Julien Louys collecting dating samples

An incredible Pliocene vertebrate fossil site occurs at Chinchilla, about four hours drive west of Brisbane, Australia. Fossils have been known from the area since the 1800’s with numerous species identified to date. The fossil fauna includes animals as diverse as diprotodontoids (the same family of mega-marsupials as Diprotodon), short- and long-faced kangaroos, wombats, koalas, and lizards. Despite the richness of the assemblage, plus fact that Chinchilla represents one of few fossil deposits of its age in Australia, relatively little research has been directed towards understanding the significance of the site.

Part of my new work, in collaboration with Dr Julien Louys (also from The University of Queensland) and Joanne Wilkinson (QueenslandMuseum), aims to address this knowledge gap. Julien is presently writing a review on the fauna, but without firm geochronological control on the deposits, we are unsure exactly how old the site actually is. By comparing the types of fossils found at Chinchilla to those from other deposits acrossAustralia, we are confident that the site is Pliocene (between 2.6-5 million years old), but where in the Pliocene is unclear.

Joanne Wilkinson surveying the site

The goal of our recent fieldtrip to the site (late February 2012) was to collect new samples for dating. The samples predominantly included sediment that is associated with the fossils. In late March, the samples will be passed on to our colleague, Dr Andy Herries from the LaTrobe University in Victoria, who is a specialist in palaeomagnetic dating. If the dating is successful, they will be the first analytical dates ever produced for Chinchilla.

Dating is notoriously difficult, time consuming and expensive, but absolutely critical for placing the Chinchilla fossil site into a reliable temporal framework for understanding its significance on a continental scale. Fingers crossed that we can get some new dates very soon!