Monday, 24 January 2011

A recently discovered fossil trove in south-west China has thrown new light on an ecosystem recovery after the severest mass extinction of life on Earth that wiped out 96 per cent of marine species and 70 per cent of land life.

The University of Western Australia's Dr Zhong Qiang Chen is a co-author of a paper, published in Proceedings of the Royal Society B, documenting the find, one of the world's most diverse Triassic marine reptile fossil populations.

A Research Associate Professor in UWA's Centre for Petroleum Geoscience and CO2 Sequestration, Dr Chen said the discovery of exceptionally preserved fossils on a hillside at Luoping in Yunnan Province would help our understanding of the early stages of the rebuilding of marine ecosystems after the most devastating crisis of life on Earth.

Around 20,000 fossils have been found so far, evidence of a spectacular revival of life on the planet after the ‘Great Dying' about 252 million years ago (the end of the Permian period).

Included in the haul are arthropods (such as insects, spiders and crustaceans), fishes, bivalves and a small proportion of plants - mostly conifers - as well as gastropods (such as molluscs and snails) and marine reptiles.

Dr Chen said the formation of the teeth and the incidence of fish scales in fossilised droppings indicated that most of the large fishes were carnivorous.  The presence of marine reptiles such as ichthyosaurs (big, finned marine ‘lizards'), which were top predators, suggests the full rebuilding of the ecosystem.

The ‘Great Dying' saw most marine species wiped out by likely basalt volcanic eruption that pumped massive volumes of greenhouse gases into the air and acidified the oceans.

This extinction event affected organisms and ecosystems more severely than the crisis which killed all dinosaurs 65.5 million years ago at the end of the Cretaceous period, when up to 75 per cent of marine species died out.  However, without the 20 small and five major extinction events that occurred in the distant past, life as we know it would not exist.

"Ultimately, we hope to recognise what types of ecosystems were fragile and easily collapsed in the ‘Great Dying' and what kinds of ecosystems were able to easily recover in the aftermath.  This will provide information for the management of modern ecosystems," he said.

Dr Chen chairs an International Geological Correlation Program working on the ‘Great Dying' and its aftermath, sponsored by the International Union of Geological Sciences and United Nations Educational, Scientific and Cultural Organisation.  He is also the lead researcher on a $570,000 Australian Research Council Discovery project. Dr Chen co-authored the paper with colleagues from Chengdu Institute of Geology and Mineral Resources, China, and Bristol University, UK.

Media references

Dr Zhong Qiang Chen (UWA School of Earth and Environment)  (+61 8)  6488 1924
Janine MacDonald (UWA Public Affairs)  (+61 8)  6488 5563  /  (+61 4) 32 637 716


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