Fossilised lizards: looking backwards to look forwards

Skink mandibles. Image: Paul Stokes.

Mandibles of a living skink (Egernia saxatilis) and two fossil Egernia specimens from Riversleigh, Queensland (Mid-Miocene).

For Dr Mark Hutchinson, Senior Research Scientist, Herpetology, looking backwards can be a good way to look forwards. Mark is using the fossilised remains of Ice Age lizards to determine where species occurred when Australia was cooler and drier than it is today.

The global warming that occurred as the last Ice Age ended would have led to different patterns of geographic distribution than those occurring in the Ice Age. Identifying which species were present at various Ice Age sites will reveal how the distribution patterns have changed.

It is a hot topic given our changing climate and Mark is hopeful his studies can make a significant contribution to the field.

Frozen animal tissues stored in the South Australian Museum’s Australian Biological Tissue Collection (ABTC) are invaluable to research scientists conducting molecular studies. By studying genes, scientists can map out phylogenetic trees that show how groups of animals are related to each other in an evolutionary sense. While this is very valuable information, it doesn’t reveal all there is to know  genes don’t necessarily tell us what an animal looks like or how they behave. Whole or parts of animals, on the other hand, can be very revealing.

Mark is collecting information on fossilised lizard specimens from several cave sites across Australia. Although lizard fossils are not abundant at large and open sites, they do tend to accumulate in the relative protection of caves. Limestone deposits at Riversleigh in Queensland have provided Mark with remains of lizards that were the immediate ancestors of many lizards currently in existence. He has also studied lizard fossils from the world heritage caves at Naracoorte, south-east of Adelaide and Wellington Caves in the Blue Mountains of New South Wales.

Mark has also benefited from preliminary fieldwork at the Nullarbor Plains caves, carried out by Dr Gavin Prideaux from Flinders University on Ice Age lizards of the area.

Much of this fossil research is done ‘in the background’, using only the South Australian Museum’s research collections, a microscope and snatches of time stolen from other work. The efforts of volunteers creating images and preparing specimens have also been invaluable.

With the support of the Museum, Mark recently took study leave in the USA, which enabled him to greatly expand his knowledge in this area.