VOLCANOES could have played a central role in the series of extinction events throughout geologic history, conclude researchers. The study, coauthored by several American geologists, claims that a volcanic eruption that lasted a million years and flooded Siberia with a mile-deep lava may have killed 80 per sent of the world's animals 250 million years ago.

The die-off - involving mainly clams, sponges and trilobites (an armoured sea animal) - is believed to have demolished many more species of living things, than the events that caused the demise of the dinosaurs about 65 million years ago. The dinosaurs had fallen prey probably to a way- ward comet or a meteor which had struck the earth.

In the study, the researchers picture a chemical-filled sky accompanying the lava flow, some ' of which could have blocked sunlight to produce a @otcanic winter. After years of global cooling, however, gases like carbon dioxide generated by the eruptions Would warm the planet and render it habitable.