UC Berkeley researchers find evidence for dinosaur-killing asteroid impact

Robert DePalma/Courtesy

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UC Berkeley researchers recently participated in a large-scale excavation that uncovered hundreds of fossils, supporting the hypothesis that the extinction of the dinosaurs may have been caused by an asteroid.

The excavation site is close to Bowman, North Dakota in the Hell Creek Formation and is known as the Tanis site. The site has been excavated for the past six years and is believed to be connected to the hypothetical mass extinction, or K-T event, of the dinosaurs 66 million years ago.

A study detailing the excavation will be published this week in the scientific journal Proceedings of the National Academy of Sciences. According to lead study author Robert DePalma, the site contains the remains of many marine creatures including terrestrial vertebrates, trees, branches, logs, marine ammonites and “many hundreds of articulated fossil fish.”


He added that studying the site could lead to a better understanding of a notable mass extinction, resulting in a better understanding of the earth and how to avoid such a massive catastrophe in the future.

“KT research in the Hell Creek is important because the better we understand the last ecologies before the impact, the better we understand the impact’s effect on those ecologies and how they respond to extinction-level events,” DePalma said in an email.

The team of researchers, including campus earth and planetary science professor Walter Alvarez and professor emeritus Mark Richards, found a large number of fossils and asteroid impact debris covered by a layer of K-T boundary clay in the sediment of the Tanis site — that’s when they realized the Tanis site was located at the K-T boundary.

He added that the timing of the sediment’s appearance matched that of large seismic waves from an asteroid impact 66 million years ago, suggesting that the impact may have caused the massive rush of water that swept the fossils inland.

“Seismic waves, and a subsequent surge, would have reached (the Tanis site) in tens of minutes,” DePalma said in an email. “As the 2011 Tohoku earthquake in Japan showed us, seismic shaking can cause surges far from the epicenter.”

Research at the site is currently ongoing — multiple researchers who are not study authors asked for research access and are currently exploring the site, according to DePalma. He added that this cooperation and collaboration has contributed to the “richness” of information obtained from the site.

The “moment-by-moment records” of one of the “most notable impact events” obtained from the Tanis site set it apart from other excavation sites, according to DePalma, who added that work on the site will continue throughout the summer.

“This is (essentially) where we inherited the planet,” DePalma said in an email. “Nothing was the same after that impact. It became a planet of mammals rather than a planet of dinosaurs, and we, as human beings, are descended from a lineage that literally survived in the ashes of what was once the glorious kingdom of the dinosaurs.”

Yao Huang is the lead research and ideas reporter. Contact him at [email protected] and follow him on Twitter at @Yhoneplus.