Monday, January 25, 2010

'There was only the sound of wind'

We're 18 million years older than we thought, footprints reveal
Toronto Star: A chance discovery in a Polish quarry speeds up evolution by 18 million years but the scientists who previously found the reigning stars of paleontology in the Canadian Arctic aren't ready to concede...

'This upsets the apple cart,' admits Dr. Per Ahlberg, lead author of the report in the current Nature... 'These are some of the most exciting fossils I have ever encountered.'

Ahlberg, an evolutionary biologist at the University of Uppsala, and his Polish colleagues uncovered secure -- meaning clearly evident -- footprints of a trackway, or walking stride, of tetrapods, four-legged animals with obvious legs and feet. That means we crawled out of the water and started walking 397 million years ago, 18 million before the previous best estimate...

The Polish discovery doesn't just rewrite the history of evolution. It also challenges why we first slunk out of the sea. 'This is about more than just footprints. We're talking about moving from one living environment to another,' said Ahlberg. 'We've argued until now that tetrapods were linked to the ecosystem, which was a seriously barren mud bank. This means they had nothing to do with the terrestrial ecosystem. They were not herbivores. They had vicious, nasty looking teeth and were carnivores.'

Poland itself was nearly tropical, sitting in the Southern Hemisphere on a land mass that included present day Europe, North America and Greenland wedged together. While these crocodile-sized animals were devouring fish and jellyfish that washed up from the sea 'nothing was in the sky. There were no birds yet, no winged insects, no reptiles,' said Ahlberg. 'There was only the sound of wind.'
Image: A fossilized footprint dating back some 397 million years and found in south central Poland, is seen on display at the Geology Institute in Warsaw; source here.