Published On: Fri, Sep 27th, 2019

The day the dinosaurs died

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It’s widely believed that the age of the dinosaurs was brought to an end by the global aftermath of a single event: a massive asteroid slamming into what is today Mexico’s Yucatan peninsula.

Now, rocks gathered from the impact site appear to confirm that hypothesis and also provide a glimpse into the catastrophically destructive minutes and hours after the fateful strike.

“Not all the dinosaurs died that day, but many dinosaurs did,” said Sean Gulick, a research professor at the University of Texas Institute for Geophysics and coauthor of a study out today in the Proceedings of the National Academy of Sciences.

Gulick was also leader of a 2016 scientific drilling mission that retrieved rock samples from the Chicxulub crater impact site offshore of the Yucatan.

“It’s an expanded record of events that we were able to recover from within ground zero,” he explained. “It tells us about impact processes from an eyewitness location.”

The eyewitness account frozen in time in those rocks tells of wildfires sparked by the incoming asteroid, massive tsunamis triggered by its impact and one missing element that would foreshadow the dinosaurs’ eventual extinction.

The impact created a crater where the Yucatan meets the Gulf of Mexico that was quickly refilled by a rush of seawater carrying bits of charcoal and other evidence telling a story of instantaneous regional devastation.

End of cretaceous KT event, illustration
Illustration of the K T Event at the end of the Cretaceous Period. When a 10-kilometer-wide asteroid enters the atmosphere (GETTY IMAGES)

“Generation of a deep crater open to the ocean allowed rapid flooding and sediment accumulation rates among the highest known in the geologic record,” the study reads.

In just one day, 425 feet of material accumulated where the asteroid hit with what some researchers estimate to be the power of 10 billion World War II-era atomic bombs.

The charcoal in the deposits is evidence that the blast ignited trees and plants, which may not have burned for very long before being extinguished by a tsunami wave. The receding waters then pulled the charred remains back into the crater.

Some researchers say the instantly lit fires could have spanned thousands of miles and that tsunami waves may have reached as far inland as Illinois.

But the rock samples also lack something which points toward what would be the death blow for all the dinosaurs that escaped the initial blast. The area around the crater is full of rocks rich in sulfur, but the samples from the core of the blast site have no sulfur at all.

This backs up the theory that the impact vaporized the sulfur in the rocks, releasing it into the atmosphere.

Once in the air, the gas reflected light from the sun back into space, creating a global cooling effect that ultimately did the dinosaurs in and led to the eventual rise of the mammals, including you and your entire family.

“The only way you get a global mass extinction like this is an atmospheric effect,” Gulick said. “We fried them and then we froze them.”

by Eric Mack for FORBES.COM

Eric Mack

Eric Mack Contributor 

ScienceI cover science and innovation and products and policies they create.



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