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The announcement is based on preliminary analysis of a core sample drilled from the Chicxulub impact crater on the Yucatan Peninsula, North Mexico. Professor G. Keller of Princeton University, USA, says that microfossils within the core sample hint at plankton that was present for at least 300,000 years after the impact.
The preliminary findings counter ideas that the impact shrouded the Earth in dust and debris, stopping sun light from reaching the surface and shutting down plant photosynthesis. This event would throw the food chain in to total chaos and lead to the rapid demise of most species, from marine micro-organisms to dinosaurs.
Professor Keller believes that the impact did not cause global devastation at the Cretaceous-Tertiary (K-T) boundary, and looks at the lack of evidence from compaction in the sample to hint that the crater is much smaller than was first thought.
The new ideas have re-ignited the debate over what caused the mass-extinction at the K-T boundary. Scientists worldwide have attacked Keller’s group claiming that the ‘microfossils’ are simply crystal spheres, and seismic studies support a major asteroid impact. The divergent views were aired at the joint conference of the European Geophysical Society, the American Geophysical Union and the European Union of Geosciences in Nice, France.
Scientists around the world are now analysing the results from the core sample from the crater, to help determine the events of 65 million years ago. Other drilling expeditions are planned, including one closer to the centre of the impact point.
More info: Nature
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