New Proof How Massive Cosmic Impact Killed Dinosaurs

First Posted: Feb 07, 2013 04:27 PM EST

Were the dinosaurs really killed off by an asteroid strike? Scientists have debated the question for years. Yet now new evidence has emerged that shows that a cosmic impact did indeed end the age of dinosaurs and eventually allowed mammals to take lead.

This most recent mass extinction occurred at the end of the Cretaceous period and is often known as the Cretaceous-Tertiary extinction event, or simply the K-T. The only survivors from this particular event among the dinosaurs are birds, whose descendants exist to this day. While this cosmic impact theory was first proposed by physicist Luis Alvarez and his son geologist, Water Alvarez, scientists have gone back and forth on whether or not this impact actually occurred. Signs of this collision were found in the form of a massive crater more than 110 miles wide near the small town of Chicxulub in Mexico, yet scientists later proved that this particular impact occurred either 300,000 years before or 180,000 after the mass extinction.

Now, though, scientists have found new evidence of a collision-driven extinction. Using a high-precision radiometric dating analysis of debris kicked up by the impact, scientists have found that the mass extinction event and the Chicxulub collision happened no more than 33,000 years apart. This would put the impact in a much better position to explain one of the reasons why the dinosaurs disappeared.

Paul Renne, an earth scientist at the University of California and his team took earth samples from a formation in Montana called Hell Creek--a remote location that possesses a bounty of fossils. Although the Chicxulub impact happened in Mexico, it deposited a very thin layer of ash which the scientists then collected and combined with other measurements in order to confirm the date of the collision.

Although the dinosaurs were probably already struggling during the time of the impact, the catastrophic event probably pushed them over the edge. This new evidence shows that, in fact, the strike was a major reason why the dinosaurs died off. In fact, it's estimated that a whopping 70 percent of all species disappeared in relatively short order.

The findings were published in the journal Science.

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