Scientists Say They've Nailed Down Most Precise Date of Dinosaur Extinction Yet

Scientists now say that they believe that they have determined the most precise date yet for the extinction of dinosaurs on Earth. Researchers from an international team of scientists have been investigating the demise of the dinosaur, and by using dating techniques on rock and ash samples, they've determined that dinosaurs died out about 66,038,000 years ago, give or take 11,000 years.

The date of extinction appears to coincide with the impact of a comet or asteroid.

Debate has been on-going in the scientific community as to whether the impact was the sole cause of a sudden demise of the dinosaurs, or if they were already in decline at the time of the massive impact. Some even question whether the impact happened as much as 300,000 years after they were already gone.

Published in the journal Science, the study involved researchers from Glasgow University in Scotland, Vrije University Amsterdam in the Netherlands, and Berkeley Geochronology Center and University of California, Berkeley.

It was in 1980 that the extinction of dinosaurs was first linked to a comet or asteroid impact. It is believed that a 110-mile wide crater known as Chicxulub located in the Caribbean off the Yucatan coast of Mexico is the result of that devastating impact. The crater is thought to have been created by an object 6-miles across, which threw debris into the atmosphere. This debris is still found around the world.

Last year, the international team decided to use these clues to put a more precise date on the extinction of the dinosaurs through examining the layers of archaeological record where they lie close to the last fossils of dinosaurs. Researchers looked at samples from Montana, where excellent dinosaur fossils have been unearthed. They also examined tektites from Haiti and volcanic ash from the Hell Creek formation in Montana.

These samples were then analyzed in labs in the U.S. using a technique called "argon-argon dating" to determine their precise ages. This particular techniques utilizes the fact that the naturally radioactive element potassium slowly decays into argon with regularity. The argon-argon method is one of the most precise ways of determining how long a particular sample has been decaying.

Researchers in Glasgow then conducted their own independent argon-argon analysis on rock samples, which then confirmed the results from the U.S.