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UW provost Mark Richards asks what killed the dinosaurs at welcome lecture

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It would have felt like the ground beneath your feet had become a ship in the middle of the ocean. Then rocks would have bombarded you from a boiling sky that was beginning to take on a hazy glow. Massive wildfires would have sprouted up as the ground burst into flames. It would have seemed like the end of the world — and maybe it was, for the dinosaurs.

According to the UW’s new provost, executive vice president, and earth and space science professor Mark Richards, that’s what the Chicxulub meteorite impact 66 million years ago in the Yucatan Peninsula would have been like. Richards gave a welcome lecture titled “What really killed the dinosaurs?” in the HUB this Tuesday.

“There’s this endless fascination about dinosaurs,” Richards said as he introduced the lecture. “When you’re a kid, you can’t make up anything better than a dinosaur. They actually existed at one time and they’re gone now.”

There are two main theories today about what killed the dinosaurs. One is the massive meteorite impact Richards described. The other is a broad and highly destructive series of volcanic eruptions. Which one of these caused the extinction is still up for debate.

“The truth is that we don’t quite know,” Richards said.

However, Richards’ research group has gathered enough evidence to propose that volcanism at the Deccan Traps lava flows in Indiadoubled following the Chicxulub impact. In turn, those increased volcanic eruptions may have further contributed to the K-T extinction.

In other words, the Chicxulub impact and the volcanic activity may have been a sort of one-two punch to the dinosaurs.

The idea came to Richards while he was on vacation in Cancún with his family. Walter Alvarez, one of the first researchers to find evidence of an asteroid impact at the time of the K-T extinction, had previously shown Richards an image of the Chicxulub crater site. Richards looked at it and realized that the limestone sinkholes near where he was staying formed a ring structure that exactly mirrored the gravity and image of the Chicxulub crater, even though they weren’t in quite the same place.

“It was literally one of those moments where I bolted up in the middle of the night when my family was asleep,” Richards said. “I don’t think they even knew I was awake.”

Michael Manga, a geophysicist at the University of California, Berkeley, had done research showing that larger earthquakes triggered volcanoes farther away. The Chicxulub impact would have been on the scale of a magnitude 11 earthquake, meaning it could have triggered any volcanic system on the planet.

The impact likely accelerated the Deccan Trapsflood basalt event, a series of volcanic eruptions around the time of the K-T extinction that covered broad stretches of India with lava. Between rock samples and fossils, a wide range of evidence points to an increase in volcanic eruptions near the time of the meteorite impact.

While no single volcanic eruption was likely big enough to cause mass extinction, a catastrophic meteorite crash combined with an extensive series of strong volcanic activity could have been devastating.

UW President Ana Mari Cauce introduced the lecture by praising Richards’ ability to inspire and excite curiosity in other people, as well as his success expanding diversity in STEM fields.

“We’re passionate about truth and driven by curiosity, and no one embodies those ideals better than our new provost, Mark Richards,” Cauce said.

Richards emphasized that strong relationships with friends and colleagues have supported him and led to new ideas throughout his scientific career.

“The most important thing … is the friendships, the colleagues, the sense of discovery that you share with other people,” Richards said. “It’s been an absolute delight. I feel like the luckiest person in the world.”

A recording of the lecture can be found online.


Reach Science Editor Leslie Fisher at Twitter: @lesliefish3r

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