Unearthing the past at Koonwarra Fossil site

A TEAM from Museum Victoria and Monash University recently excavated a site near Koonwarra which has yielded many intriguing fossils, the importance of which may warrant further investigation.

Museum of Victoria’s Senior Curator, palaeontologist Dr Thomas Rich and fellow palaeontologist Professor Tim Flannery, have been leading the team in the dig, which is the third since the fossils were discovered in the 1960s by Country Roads Board workers during straightening of the highway.

Included in the finds are evidence of non-flowering plants, such as conifers and ferns and remains of a Chinese ginkgo tree. Fossilised insects, including two fleas, have also been discovered and have intrigued the team as it appears this type of flea would have lived on the blood of furred animals – but in an age of reptiles.

A number of fossils have also been found which are the same as those discovered in India. This can be explained by the fact that India and Australia were part of Gondwana – the land mass which existed before it began breaking up in the early Jurassic period.

The fossils date to around 120 million years of age – the same age as those found at the Flat Rocks Fossil Site at Inverloch.  At the Koonwarra site, many rocks have been found to contain finely detailed impressions of fish which appear similar in size and appearance to sardines.  As the remains decayed over time, iron oxide has filled the impressions left in the rock by the fossil, leaving very visible details.

“With the diversity and quality of preservation we are finding, this is a world-class deposit,” said team member, geologist Gary Wallis of Fish Creek.

Gary explained that 120 million years ago the Strzlecki Ranges were uplifted to their present height and lakes and swamps were formed in the large valley. Fossils found in former rivers or streams are often not as well preserved as those in lakes which have been subjected to much less water movement over the course of time. This means there is a good chance that if a major find is made at Koonwarra, the preserved detail could be very revealing.

While interested in the fish, insects and flora already discovered, what Dr Rich is really excited by is the similarity of the rocks to those at a fossil field he visited in China, where 31 intact tetrapods (four-limbed vertebrates) were discovered.

Dr Rich worked on the Koonwarra site 30 years ago and believes that somewhere within perhaps a 50km radius of Koonwarra, are similar fossils to those he saw in China. The discovery of eight feathers at the Koonwarra site may indicate that remains of early birds or feathered dinosaurs could be found.

The fossils taken from the site will be studied back at the Museum of Victoria and the results will determine if further investigation is warranted.

“We are really hoping to find skeletal remains,” said Dr Rich, who is very hopeful of further investigations taking place.

“I don’t know exactly where or when the skeletal remains that we’re hoping for will be found. It may not even be in my lifetime and the person may not even have been born yet, but it will happen one day,” Dr Rich said.

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