Pradip K Bose has found convincing evidence from a site close to Churhat that the first multiple-celled animals evolved about 1.1 billion years ago, a finding that will stretch back the chronology of animal life by a good 500 million years. The discovery, says Prabha Kalia, an expert on fossils and Head of the Department of Geology, Delhi University, will lead to textbooks being ``re-written.'' Bose's paper, written along with two collaborators from Germany, is the cover story of the October 2 issue of the reputed American journal, Science

Till now, the earliest known fossil records -- discovered only recently in China -- indicated that multi-celled animals had evolved about 600 million years ago. Bose found wiggly groves on thesurface of ancient sandstone from a road crossing in Churhat, better-known in political circles as the hometown of Congress leader Arjun Singh.

The Calcutta-based geologist says these are tracks left by worm-like animals -- about half-a-centimetre thick -- while burrowing though the sea floor in ages gone by. This find from India is ``staggering,'' if it is true, says Charles Marshall, an expert on evolution from the University of California, Los Angeles, for it provides the ``first evidence of macroscopic animals.'' The scientists have used the most sophisticated dating techniques -- called the vision track method and potassium argon dating -- to convincingly establish the vintage of the Churhat Sandstone.

Bose says the trace fossils are preserved in the Churhat Sandstone, which contains sand beds that built up during storms about a billion years ago. The tops of many sand beds were covered with a microbial mat that blanketed the floor periodically and protected the sand below from disturbances below themat, using them as a source for food and oxygen, since the water within the sand layers was probably poor in oxygen.

An important and often controversial consideration for researchers analysing trace fossils is that physical processes can also create patterns in sedimentary rocks that look very similar to tracks left behind by animals. According to Adolf Seilacher, the German collaborator of Bose, the Churhat findings are best explained as the legacy of burrowing animals. The diameters, for instance, vary from tunnel to tunnel, but remain constant along each individual tunnel. The tunnels also do not resemble the structures commonly caused by physical processes and are similar to younger trace fossils known to be produced by animals that developed from an embryo and that contain three outer membranes, as do worms, or what in the lexicon of scientists are called the `triploblastic animals'.

The discovery also raises many questions than it answers, for there's a huge gap of 500 million years left to beexplained. As of date, no fossil records are available for the period between the Chinese and Churhat finds. Is it that multi-celled animals evolved once around 1.1 billion years ago and then died out only to appear once again as a highly successful evolutionary group some 600 million years ago? The same group has evolved into the human form.

Experts say the Churhat discovery should prepare us for many more surprises and maybe scientists haven't yet looked for the right kind of fossil records in the right places. ``The site itself (where this significant discovery was made) remains unprotected,'' says Bose, pointing out that it is open to plunder by bounty-hunters.

The Churhat site is also threatened because of development activities, like the widening of the road being undertaken by the district authorities. Even the main canal of the nearby Band Sagar Dam, which is to provide much-needed water for Sidhi district (where Churhat is located), is likely to pass through the area. Urgent steps are needed,therefore, to secure the area after this path-breaking discovery becomes public knowledge, as it may hold deep within many more secrets on the evolution of humans.

Pallava Bagla is the India Correspondent of Science

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