New fossils found fix the age of mountain basin in Vindhyan

Published: Tuesday 15 May 2007

new fossil finds in the Vindhyan basin in central India have, for the first time, fixed the age of the evolutionarily significant mountain basin, not very long ago considered palaentologically dead.

In the first record of extensive fossil assemblage unearthed from the basin, Chirananda De of the Geological Survey of India (gsi) has found evidence that the region dates back to the Ediacaran age (about 543 to 600 million years ago). Earlier, the exact age of the basin was not known and the Vindhyan region had been attributed a rough isotopic age.

The fossils were found in two separate zones in the Lakheri and Sirbu formations of the Bhander Group in the basin. There were nine kinds of coelenterates, one kind of arthropod and a few unnamed, possibly new, forms of sponges or coelenterates.

De's findings were published in the Journal of Earth Sciences recently. "This find also extends the bio-geographic range of the Ediacaran fossils to peninsular India," De said.

The significance of the find in terms of establishing theories of evolution is that it chronicles the existence of a series of organisms--coelenterates, pro-arthropods and annelids--in the same fossil assembly. The fossils also provide an interesting inter-continental correlation of the Vindhyan basin with similar ranges in Newfoundland, South Africa and Antarctica, from where such assemblages have been previously reported by scientists.

"These are significant, soft-bodied fossils also having strong affinities to the Ediacara assemblages found in South Australia and White Sea Region of Russia. The fossils reveal that the area was an energetic, wave-tide dominated, shallow, marine environment," De inferred in his paper.

Similar basins of peninsular India are a series of underformed and unmetamorphosed rock sequences dominated by sandstone, shale and limestone. The latest find of morphologically diverse fossil forms has established the rich wealth of Ediacaran organisms in the basin, for the first time.

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