Fishing for fossils

08 September, 2008

Hunting for fossils
Museum staff search the nodules littering the ground for fossils at the site.
Image: John Long
Source: Museum Victoria

In July–August this year, an expedition of local and international scientists searched the remote Kimberley district in the far north of Western Australia for fossil fishes. Dr John Long, Museum Victoria’s Head of Sciences, led the expedition. The team spent two weeks searching the sites, which are to the east of Fitzroy Crossing, and collected about 130 high quality fossil specimens.

The site is renowned for its extraordinary preservation of three-dimensional fish skeletons that are 375–380 million years old. It has already yielded the world’s oldest mother, a fossil fish with an embryo inside it, and the spectacular Gogonasus specimen (meaning “snout from Gogo”, this was a lobe-finned fish that lived 380 million years ago).

The recent  expedition involved several museum staff, including Collections, Research and Exhibition Director Robin Hirst, who joined the dig for four days. Dr Tim Senden from the Australian National University and Dr Kate Trinajstic of the University of Western Australia, who are currently collaborating in the fish fossil work with Museum Victoria’s team, also participated in the expedition, as did scientists from China and Sweden who flew to Australia for the dig.

“The new fossils we found include some very significant scientific discoveries”, Dr Long said on his return. “The gems of the trip include representatives of fish groups never before found at the Gogo sites. Once prepared in stunning 3-D form they will provide a wealth of new data on the anatomy and evolution of these early vertebrate groups. Another amazing find was an armoured placoderm fish with some of its internal soft organs preserved.”

At the museum, the Gogo fish fossils are prepared in weak acetic acid which dissolves the limestone away from the   bones, revealing the uncrushed perfect skeletons. Some specimens also have preserved ancient muscle, nerves and capillaries. The mother fish fossil discovered earlier this year showed that umbilical feeding structures are sometimes also preserved in the fish fossils.

“We will prepare the fossils over the next few years and describe the new discoveries using state of the art analytical techniques, such as ultrafine CT scanners”, Dr Long explained.

Some of the best specimens found by the expedition will be put on public display in Melbourne Museum’s forthcoming new gallery on the evolution of life and landscapes, which is scheduled to open in late 2010.

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