The Asteroid that Killed the Dinosaurs

The hypothesis that an asteroid collision was the cause of the extinction of the dinosaurs has been around for several decades now, but recent research has provided new support for the theory.

The idea that a cosmic impact ended the age of dinosaurs in what is now Mexico now has fresh new support, researchers say.

The most recent and most familiar mass extinction is the one that finished the reign of the dinosaurs — the end-Cretaceous or Cretaceous-Tertiary extinction event, often known as K-T. The only survivors among the dinosaurs are the birds.

Currently, the main suspect behind this catastrophe is a cosmic impact from an asteroid or comet, an idea first proposed by physicist Luis Alvarez and his son geologist Walter Alvarez. Scientists later found that signs of this collision seemed evident near the town of Chicxulub (CHEEK-sheh-loob) in Mexico in the form of a gargantuan crater more than 110 miles (180 kilometers) wide. The explosion, likely caused by an object about 6 miles (10 km) across, would have released as much energy as 100 trillion tons of TNT, more than a billion times more than the atom bombs that destroyed Hiroshima and Nagasaki.

New findings using high-precision radiometric dating analysis of debris kicked up by the impact now suggest the K-T event and the Chicxulub collision happened no more than 33,000 years apart. In radiometric dating, scientists estimate the ages of samples based on the relative proportions of specific radioactive materials within them. [Wipe Out: History’s Most Mysterious Mass Extinctions]

“We’ve shown the impact and the mass extinction coincided as much as one can possibly demonstrate with existing dating techniques,” researcher Paul Renne, a geochronologist and director of the Berkeley Geochronology Center in California, told LiveScience.

“It’s gratifying to see these results, for those of us who’ve been arguing a long time that there was an impact at the time of this mass extinction,” geologist Walter Alvarez at the University of California at Berkeley, who did not participate in this study, told LiveScience. “This research is just a tour de force, a demonstration of really skillful geochronology to resolve time that well.”

The fact the impact and mass extinction may have been virtually simultaneous in time supports the idea that the cosmic impact dealt the age of dinosaurs its deathblow.

“The impact was clearly the final straw that pushed Earth past the tipping point,” Renne said. “We have shown that these events are synchronous to within a gnat’s eyebrow, and therefore, the impact clearly played a major role in extinctions, but it probably wasn’t just the impact.”

The new extinction date is precise to within 11,000 years.

“When I got started in the field, the error bars on these events were plus or minus a million years,” added paleontologist William Clemens at the University of California at Berkeley, who did not participate in this research. “It’s an exciting time right now, a lot of which we can attribute to the work that Paul and his colleagues are doing in refining the precision of the time scale with which we work.”

I can’t help wondering if there is any chance that some species of dinosaur might have been intelligence, perhaps even civilized. No fossils suggesting such a possibility have ever been uncovered, but given the haphazard way in which fossils are made and preserved, it is doubtful that that we know of even 1% of all the organisms that existed at any given time. If an asteroid were to kill us off, I wonder if any remains of our civilization would be recognizable after 65 million years. Considering that it seems that quite a few asteroids have passed, and will be passing extremely close by, maybe a far future paleontologist will be wondering what happened to the mammals.

By the way, I have been reading The Peshawar Lancers by S. M. Stirling. The book takes place in an alternate history in which an asteroid or comet struck the Earth in 1878, destroying civilization in the Northern hemisphere. One hundred fifty years later, the descendants of the survivors are finally reaching the levels of technology we had around 1920.

 

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