IANS

A Bengaluru based geologist has discovered 2,000-million-year-old "prokaryotic" microfossils — considered to be the earliest form of life — from the Indian subcontinent in the Gwalior basin of the Bundelkhand region near Jhansi. The discovery by Naresh Ghose, formerly geology professor at Patna University, was reported at the recent annual convention of the Indian Geological Congress in Nagpur.

Microfossils, perhaps the most important group of all fossils, are the tiny — less than one millimetre in size — remains of bacteria, fungi, animals, and planktons. The shape and distribution of the occurrences of the micro-fossils in carbonaceous material, strongly support the debris to be that of a micro-organism, Ghose told the convention. An individual micro-fossil consists of an outer rim of recrystallised silica (quartz), while the core is composed of carbonates (calcite) with a mixture of iron-bearing material, he told this correspondent.

Ghose found these in the 2,000-million-year-old microfossils in the black carbonaceous shale from the Bundelkhand region of the Gwalior basin in Central India.

Incidentally, the appearance of primitive life in the black shale coincides with the "Great Oxygenation Event" that brought the transition of Earth's atmosphere from oxygen-poor (anoxic) to oxygen-rich status. The earth's atmosphere since then has been responsible for transformation of inanimate objects (inorganic elements and compounds) to the animate world of today with millions of diversity in the animal kingdom.

"The present study reports for the first time the presence of "organogenic" microfossils — derived from living organisms — in black shale immediately underlying the volcanic rock of the Gwalior basin," Ghose said. The identity of microfossils has subsequently been endorsed by experts from different disciplines, including Professor Jai Krishna, a leading palaeontologist from the Benaras Hindu University.

"Therefore, the microfossils (Prokaryotic-RNA cell) in the Gwalior basin may be regarded as the confirmed oldest existence of life dated about 2,000 million years ago ever to be recorded from the Indian subcontinent," Ghose said. Ghose found the microfossils while studying thin sections of sediments (called "par" formation) containing the siliceous black shale in the uppermost part coexisting with fine layers of limestone and particles of river-borne and volcanic origin.

"This important discovery was made using a simple and inexpensive device like a microscope without the aid of any sophisticated instrument," he said. The deposit of black shale is a "universal" feature underlining a lava flow and associated with the formation of organic debris on the death of marine animals. Abundance of black shale is a major source of hydrocarbons and gas hydrates. "The USA is utilising black shale as an alternative source for hydrocarbons and is a leading exporter due to its technological advancement," Ghose said.