A precise date
An improvement in dating techniques with argon-argon allows us to place more correctly the extinction of large reptiles.
When did the dinosaurs become extinct? 65.5 million years ago, more or less 300 thousand years. This is the answer, or at least it was until yesterday. Thanks to a more refined timing technique, researchers from Berkley, California, have reduced by nearly 10 times the range of error, identifying with extreme precision the "moment" in which dinosaurs were extinct, which matches the passage between the era of geological Cretaceous and the Tertiary. The new answer is 65.95 million years ago, with a margin of error of only 40,000 years.
When did the dinosaurs become extinct? 65.5 million years ago, more or less 300 thousand years. This is the answer, or at least it was until yesterday. Thanks to a more refined timing technique, researchers from Berkley, California, have reduced by nearly 10 times the range of error, identifying with extreme precision the "moment" in which dinosaurs were extinct, which matches the passage between the era of geological Cretaceous and the Tertiary. The new answer is 65.95 million years ago, with a margin of error of only 40,000 years.
As reported in Science, Paul Renne, director of the Berkeley Geochronology Center, and his group, have perfected the method of dating with argon-argon, developed in the same university in the sixties and commonly used to date rocks and fossils. The method is versatile but little accurate than other techniques, such as uranium-lead, because it has an uncertainty of 2.5 percent. This is irrelevant to events close to us, but when it speaks of the dawn of the Solar System, that is 4.5 billion years ago, one percentage point corresponds to 50 million years. Renne and his colleagues are now able to lower the range of error to 0.25 percent, which is comparable to that of other methods.
"The importance of technical cooperation with argon-argon is that this is the only method which covers almost the entire history of the Earth" Renne said. The technique is now also used to date the formation of meteorites.
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