Asteroid 'influenced evolution'

The Ediacarans are a weird bunch of organisms that included the world's first large-scale complex life. During the time they lived (635-542 million years ago) in southern Australia, the Earth experienced at least one cold snap that may have covered much of the Earth in ice.

At that time, southern Australia lay near Equator and low latitudes were devastated by impact of a 4.7-km-diameter asteroid that left a 90-km crater in central South Australia.

Now, a team of Australian geologists shows that this massive impact -- which struck with an estimated energy of 5.2 million megatons of TNT - coincided with period of glaciation, the 'Australian Journal of Earth Sciences' reported.

The effect of this double whammy -- extreme cold and killer asteroid -- could have been a major factor influencing the evolution of the Ediacarans, say the geologists.

"Release from the combined environmental stresses of a frigid, glacial climate near sea level and a major impact in low latitudes may have been a factor influencing subsequent Ediacaran biotic evolution," said team leader Victor Gostin of University of Adelaide.