NEW DELHI, October 10: A British scientist has disputed the recent claims by an Indo-German team that the tiny fossil tunnels found in churhat sandstones in central India belonged to burrowing worm-like creatures that existed 1,100 million years ago.Martin Brasier of the Department of Earth Sciences in the University of Oxford said, the team wrongly interpreted the structures as ``tunnels'' and the rocks where they found the structures are only 560 million years old and not 1100 million years as claimed.The discovery by the team comprising Adolf Seilacher and F Pfluger of Germany and Pradeep Bose of India aroused great deal of interest in the scientific community because, if true, it would double the time span of the animal fossil record and thereby push back the date of origin of animal life on earth by 500 million years.The team made this claim by arguing that the half a centimeter wide burrows it discovered were too large to have been made by single-celled organisms as these could be made only by``triploblastic'' or worm-like creatures that had a gut and a belly.The scientists placed the age of these fossils at more than 1,000 million years on the basis of the published age of the rocks as determined by potassium-argon and fission track dates.The branching of tunnels observed by the Indo-German team ``implies a behavioural sophistication which is thought to have appeared about 560 million years ago'' and not earlier, he wrote in his report.But their claims received a jolt with the publication of Brasier's report in the October 8 issue of the international science journal Nature.According to Brasier, single-celled organisms called ``protists'', including Cambrian forms, can be large in size and can make burrows of the observed diameter.On the claim that the churhat sandstones are 1,100 million years old, Brasier said these dates were mostly obtained in the 1960s.A very recent study by R J Azmi of the Wadia Institute of Himalayan Geology in Dehradun has established the age ofrohtasgar limestones - immediately above the churhat sandstones - as little more than 540 million years old, close to the beginning of Cambrian explosion. Brasier concluded the fossil evidence obtained by the Indo-German team does not support the view that animals started emerging more than a billion years ago.Modern studies of geochrnology are urgently required for estimating the precise age of the Vindhyan rocks and to resolve the controversy, the British scientist said.
