If You Assume You Perceive the Demise of the Dinosaurs, You’re Fallacious

“There were dozens of hypotheses and basically no one took any of them seriously.”

That is, until Berkeley scientists – led by Luis Alvarez (a Nobel laureate in physics) and his son geologist Walter Alvarez – came up with the idea that the earth was struck by a meteorite or comet the size of San Francisco.

The theory and its supporters received a major boost a few years later with the discovery of a 110-mile-wide crater on what is now Mexico’s Yucatan Peninsula.

“With the discovery of the smoking weapon, the fact that there was a large meteorite became widely accepted,” Marshall said. “So it started to develop into the two hypotheses on meteorite versus volcanism.”

Charles Marshall examines a cast of a bird related to puffins and the great auk found in the Monterey Formation in southern California. (Daniel Potter / KQED)

In fact, volcanoes have been difficult to keep off the list of known suspects. Hundreds of millions of years ago, every other major extinction (with the exception of today’s) was associated with volcanism.

Around the same time as the meteor strike and the disappearance of dinosaurs from the fossil record (along with many species to tiny marine life), there was also a massive wave of volcanic activity in India – in a place known as the Deccan Traps.

Scientists have been arguing back and forth for years: Impact! Volcanoes! Impact! …

Until recently, when Berkeley geophysicist Mark Richards offered this idea: “I realized that the size of the impact is probably large enough to have triggered volcanic systems around the planet.”

Bigger than big

Richards calculated that the energy of a rock the size of Mount Everest from space was enough to trigger an 11-magnitude quake. This is not a typo. When I told Richards that I thought the scale would only go up to 10, he told me that it was actually not true.

In terms of earthquakes, 10+ is a nightmare. Such a quake would be a hundred times worse than the “big one” that hit San Francisco in 1906. Richards says it shook the globe – even the volcanoes on the other side of the world in India.

A relative of today’s Komodo dragon, the owner of this skull (left), wore flippers and could grow to be more than 20 feet long. To the right in Charles Marshall’s laboratory sits an Allosaurus foot. (Daniel Potter / KQED)

“So the idea is that the impact may have put the system into high gear.”

Richards carefully says that if he’s right and the two events are linked, we still don’t know exactly what killed the dinosaurs. Rather, the proposal points the way for a new investigation, says Paul Renne, director of the Berkeley Geochronology Center and co-author of Richards’ paper.

“We just have to give up the thought that it is one thing or the other,” said Renne.

Both the impact itself and a volcanic wave would have the potential to trigger massive eruptions of noxious gases that lead to sharp temperature fluctuations.

One factor could have been the release of CO2, for example from so much vaporized limestone, which, along with other greenhouse gases, leads to a long-term warming effect.

India’s Deccan Traps, described by geologists as a “great igneous province,” were formed over hundreds of thousands of years as layer upon layer of lava flowed and cooled, around the same time the dinosaurs died. (Paul Renne / BGC)

Renne says there could also have been an abundance of sulfate aerosols, “which, when released into the atmosphere, can actually reflect enough sunlight, causing cooling.”

In fact, one could argue for a double event – first sudden cooling, followed by a long, hot period from the greenhouse effect. Whether the dinosaurs died in a single bad weekend, or the lifespan of an animal when the food web collapsed, or several millennia, remains unclear.

“The potential effects of an impact or massive volcanism can be the same in many ways. The symptoms would be indistinguishable, ”says Renne.

Increase in precision

In order to better understand the effects and their possible connection with the eruptions in India, a narrower data range will be determined in the next step. For Renne, this means using a basement room full of mass spectrometers to test rocks from the Deccan traps. In the hallway in front of his office, canvas sacks full of such stones are piled up.

“I am a rock lover and I have a lot of beautiful rocks and large crystals. These are some of the ugliest rocks you will ever see, ”said Renne, pulling out a sample that, to my untrained eye, might as well have been gravel from a nearby quarry.

A fossilized pteranodon hovers over the Tyrannosaurus Rex in the Museum of Paleontology at the University of California at Berkeley. (Daniel Potter / KQED)

Dating these rocks is a slow process, with a few tens of milligrams shipped from the state to be irradiated and then sent back for testing. It can take months.

Nearby is a wood-paneled room that houses a magnetometer – another tool for dating prehistoric rocks. This is the Courtney Sprain’s specialty; She is a Ph.D. Student who also wrote Richards’ paper.

Sprain spends part of the summer in Montana collecting samples from coal seams and has told me that at the end of each day she resembles a chimney sweep.

When the Earth’s magnetic core shifts (we’re not sure why this is happening) it leaves a record in the rock. Sprain teases these cues to refine the timescale.

“We get an accuracy of 20,000 years,” she says, “while before it was 500,000, a million.”

Really ideal, albeit unrealistic, would be the accuracy up to the day of the week the impact occurred. But it would be helpful to bring it under 10,000 years.

Geologist Eldridge Moores, a distinguished professor emeritus at UC Davis known for his role in the John McPhee book “Assembling California,” says it is like a detective trying to find out the exact time someone died.

“You have to know that – this is essential information before you can answer the next question, that’s why. The same goes for the dinosaurs. “

Moores was sitting with me in his Davis house, a copy of Mark Richards’ newspaper on the dining table in front of him, when I asked him: Do we know what killed the dinosaurs?