20020820

Changes in climate may have reduced the northern dinosaur population dramatically millions of years before the impact of the Yucatan impact 65 million years ago. The results of a research in Drumheller Valley, southern Alberta, suggests that more than 50% of the dinosaur communities that flourished during the Late Cretaceous in this area died out before the end of this time period, they were victims of a gradually cooling climate. Oxygen isotopes in the tooth enamel of meat-eating dinosaurs, showed temperatures in Alberta dropped from about 25 C to 15 C. The researchers came to the startling realization many creatures and plant life in this area had vanished over several million years. Such a scenario would left the remaining dinosaurs vulnerable to catastrophe, which came in the form of an asteroid.

According to David Eberth curator of sedimentary geology at the Royal Tyrrell Museum of Paleontology in Drumheller. The research shows that that dinosaur communities were under stress, at least in the northern reaches of North America, well before the asteroid impact. Eberth thinks that this is the first solid evidence of a decline in dinosaur communities prior to the asteroid impact that was the final death knell for all of the dinosaurs. The data is being compiled and will be submitted for publication within the year, but the project will continue for another two years.

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