Impact sans disaster

Popigai -- a mysterious place in the far northern reaches of the Siberian tundra. Researchers from Russia and Canada have found that a meteorite hit the Popigai 35.7 million years ago. Recently, another group of scientists had pinned the age of a 80-km-wide crater in Chesapeake Bay to nearly the same time. These two impacts in the past 65 million years are considered to be the biggest of all time. Scientists predicted that both the impacts might have led to extinction of life forms from the Earth. Their hypothesis was based on the findings that a similar impact 65 million years ago at the end of the Cretaceous Period had wiped out the dinosaurs and many other forms of life from the Earth. However, palaeontologists have found that the combined impact of Popigai and Chesapeake did not have any major effect on the Earth. According to them, there were actually two peaks of extinction, one 37 million years ago and the other 33 million years ago. Neither of the Popigai-Chesapeake impacts coincide with this period, according to Donald Prothero, a palaeontologist at Occidental College in Los Angeles, usa ( Discover , Vol 18, No 1).