Julien is a vertebrate palaeontologist and palaeoecologist at the Australian Research Centre of Human Evolution (ARCHE), Griffith University, Brisbane. His current position is Professor of Palaeontology and he is also Deputy Director of ARCHE. His major research projects focus on adding to Sumatra's Pleistocene fossil record, and understanding its evolutionary and environmental history (funded by 2017 Australian Research Council (ARC) Future Fellowship and 2022 ARC Discovery Project); and the palaeontology of Australian underwater caves (funded by 2022 ARC Linkage Grant).
He received a Bachelor of Science and a Bachelor of Mathematics (2003) from the University of Newcastle, Australia and a Bachelor of Sciences (Hons, 2004), and PhD (2008) from the University of New South Wales, Sydney. He completed a three year (2008-2011) Postdoctoral Research Assistant position at Liverpool John Moores University, UK, examining the use of taxon-free variables in palaeoecological analyses. He then (2012) worked for 12 months at the Queensland Museum as Curator of Geosciences, and a University of Queensland Postdoctoral Fellow (2012-2013) examining Australian marsupial palaeontology, particularly Pliocene faunas, as well as community ecology of Pleistocene/Holocene small mammal assemblages. Between 2013-2017 he was a Postdoctoral Research Associate at the Australian National University, Canberra. He took up a permanent position at Griffith University in 2017, completing an Australian Research Council (ARC) Future Fellowship (2017-2021), where he was promoted to Associate Professor in 2019, and Professor in 2023.
Julien has conducted hominin and other mammal palaeoecological research in Australia, Kenya, Saudi Arabia, Mongolia, Indonesia, and Timor-Leste. He has published >100 articles in peer reviewed journals, in addition to several book chapters and edited volumes. He is a passionate caver, certified cave diver, and scientific cave diver. His research has been funded domestically and internationally, including grants from the ARC, The Ian Potter Foundation, The Wenner-Gren Foundation, National Geographic, and The Leakey Foundation.