Fossil found in copulation stage

Indian scientists have found a 65-mn-yr-old fossil, showing two tiniest members of animal family in sexual union that can't be seen with naked eye.

Scientists in Lucknow have unearthed a 65-million-year-old fossil, showing two tiniest members of the animal family in sexual union.

'It is the first time that sexual copulation has been discovered in a fossil state,' according to Ranjeet Kar at the Birbal Sahni Institute of Palaeobotany (BSIP) in Lucknow.

However, one needs a microscope to see the fossil sex frozen in time because what Kar and co-workers have captured is between 'swarm cells' that are smaller than the width of a human hair. Swarm cells are one of the three stages in the development of the fungus Myxomycetes, also known as 'slime moulds' that are classified due to their creeping behaviour.

Having two flagellas, swarm cells are motile and sexually reproduce by 'fusing' to produce what is known as 'zygote.' Once they are fused, the flagellas are lost. Kar said that the fossil showing two swarm cells in 'fused' position and shedding of their flagellas is evidence that the two cells had sex.

'The sexual organs (of swarm cells) being delicate and the time of conjugation short-lived, it is indeed rare to get this stage (of conjugal union) in the fossil state,' the BSIP scientists have reported in the journal Current Science.

The slime moulds -- strikingly colourful in yellow, orange or red -- live in cool, shady, moist places on decaying wood, leaves or organic matter, Kar says the specimens obtained from the sediments at Jabalpur in Madhya Pradesh, are not comparable to any fossil forms of swarm cells recorded anywhere in the world so far.