* Astronomy

A huge meteorite that hit the Irish Sea and left a crater the size of Surrey may have helped giant dinosaurs come to dominate the planet, scientists have claimed.
The researchers, who have analysed rock formations in the British Isles and France, believe the impact caused a tsunami that swamped large parts of Europe.
They argue the meteor strike 200m years ago and others like it may have led to changes in the Earth’s climate that caused some species to die out and others to dominate.
It has long been argued that the extinction of the dinosaurs 65m years ago was caused by a massive asteroid strike.
But scientists have wondered why dinosaurs, which had previously been relatively puny, began to develop into giants such as Tyrannosaurus rex about 200m years ago.
One theory is that increases in carbon dioxide in the atmosphere led to bigger plants, which encouraged the development of bigger herbivores and then a growth in the size of predators.
Other scientists claim an impact by a meteor may account for the relative suddenness of the change.

"There was a relatively sudden increase in the size of dinosaurs around the time we have dated this impact. This impact may well have been a factor in the changes that were going on" - Michael Simms, curator of palaeontology at the Ulster Museum in Belfast who led the research.

Simms’s team found evidence of the shock probably caused by a meteorite, which may have been up to two miles wide and hit at 18,000mph, in data from boreholes and rock formations covering 100,000 square miles.
They have not found the crater itself, but they believe the meteor may have hit what is now St George’s Channel, between Pembrokeshire and the Irish coast. Much of western Britain and Ireland was under water at the time.
The crater may have been more than 30 miles wide but would now be deeply buried beneath the sea floor.
In the research, published in an academic journal, Simms looked for signs of impact rippling out from the crater in sediment that would have been affected by the shockwave. He analysed rock and borehole data and found the same unique pattern at every site he looked at, from Northern Ireland to Yorkshire and Dorset.
Paul Barrett, a palaeontologist at the Natural History Museum in London, said Simms’s theory was "an interesting idea. This is the first geological suggestion that there was an impact at this time. What we really want to back this up is a crater of the right age."


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-- Edited by Blobrana at 00:21, 2006-10-09