August 19, 2010
CLAIMS by US geoscientists that they have discovered the oldest known animal life have been greeted with scepticism by Australian experts.
Paleontologists such as Jim Gehling with the South Australian Museum say it is no surprise that simple sponge-like animals lived 600-650 million years ago, as reported yesterday in the journal Nature Geoscience. But they are far from convinced they are what the Princeton University team has found.
"To argue these were sponges is a difficult proposition. They look like Coco Pops, " said Dr Gehling.
Moreover, Dr Gehling said better, older fossils had been found three years ago by University of Melbourne geologist Malcolm Wallace and his team. Dr Gehling suggested that competitive pressure might have been the reason Dr Wallace's group has been unable to publish their results.
The Australian understands that one of the co-authors of the contentious paper is a reviewer for the journal Science, to which Dr Wallace's group has submitted a paper. It is not clear whether the reviewer has read the paper but Dr Wallace acknowledged that "we've had difficulties getting our results published". He preferred not to discuss Dr Gehling's suspicions. He did affirm that his group's finds were roughly 20 million years older than those reported by the Princeton team, headed by paleontologist Adam Maloof.
Along with colleagues at New Jersey-based Princeton and the Smithsonian Institution in Washington DC, Professor Maloof reported that calcified material found in limestone rocks in the Flinders Ranges of SA were probably "sponge-grade metazoans" -- simple multi-celled animals.
But Dr Gehling said the the tiny fragments described as sponges by Professor Maloof and his colleagues were poor candidates for the oldest animal honours.
Dr Gehling said Dr Wallace's team had found "definite fossils", centimetres in size. He said the Melbourne fossils came from what had been a deepwater reef, while the Princeton group's material was from what was then highly disturbed shallow water.