Wednesday, December 21, 2011

Dead marine plankton provide clue to the extinction of dinosaurs during K-T period

Syed Akbar
Hyderabad:  The Krishna-Godavari basin near Rajahmundry has now
helped scientists solve the age-old mystery of disappearance of
dinosaurs and other animals, 65 million years ago.

A team of scientists from the USA and India collected samples of dead
plankton (microorganism) from the oil wells of the Oil and Natural Gas
Commission in the KG basin and subjected them to paleontological
studies. The results showed that dinosaurs and other animals were
wiped out of the earth, not because of a single meteor strike, but due
to intense volcanic activity in the Deccan region.

There were at least three major volcano eruptions in the Deccan, which
led to intense flow of lava, heavy dust and poisonous gases like
carbondioxide and suphur dioxide. The gases surrounded the earth
killing a majority of animals including the giant reptiles.

The volcanic eruption had its impact right through the present day
Mumbai and Hyderabad to Rajahmundry and down. The Indo-US team
comprised Dr Gerta Keller of Princeton University, and PK Bhowmick, H
Upadhyay, A Dave, AN Reddy and BC Jaiprakash, of the ONGC. The
researchers collected the plankton from the sediment trapped in the
Deccan lava flows, the largest flows on earth, near Rajahmundry. They
reject the prevailing theory that the extinction was caused by a
single large meteorite.

“Marine sediments from Deccan lava flows show that the population of a
plankton species widely used to gauge the fallout of prehistoric
catastrophes plummeted nearly 100 per cent in the thousands of years
leading up to the mass extinction,” Dr Keller told this correspondent.

"Our work provides the first one-to-one correlation between the mass
extinction and Deccan volcanism," she added.

The marine sediments preserved between lava flows from the second- and
third-phase eruptions contained evidence of the KT
(Cretaceous-Tertiary) boundary, a thin, worldwide geological layer
that marks the mass-extinction event. The activity wiped out nearly
100 per cent of planktonic foraminifera and ultimately initiated the
Cretaceous-Tertiary mass-extinction event. A less severe third
eruption phase occurred roughly
300,000 years after the mass extinction and kept the Earth nearly
uninhabitable for another 5,00,000 years.

According to the  researchers, the number of species evolving remained
low, and existing species dwarfed during the 5,00,000-year period
after the mass extinction. New, larger marine species did not appear
until after the third phase when Deccan eruptions went dormant.
Gradually, life began to recover as the atmosphere became less

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