Pieces of Asteroid That Killed Dinosaurs May Have Been Found


GREENBELT, Md. — Scientists studying the North Dakota site, a time capsule of that cataclysmic day 66 million years ago, said that intact slivers of the impactor that killed the dinosaurs had been discovered.

Scientists estimate that the object that struck the Yucatán Peninsula in what is today Mexico was about six miles wide, but the object’s identity has not changed. moot point. Was it an asteroid or a comet? If it was an asteroid, what type was it – a solid metallic or a pile of rubble stone and dust held together by gravity?

“If you can actually identify it and we’re on our way to doing it, then you can really say, ‘It’s amazing, we know what it is,'” said palaeontologist Robert DePalma, who led the excavation of the site. said during a talk Wednesday at the NASA Goddard Space Flight Center in Greenbelt, Md.

A video of the conversation, followed by the discussion between Mr DePalma and leading NASA scientists, will be posted online in a week or two, a Goddard spokesperson said. Many of the same discoveries will be discussed in: “Dinosaurs: The Last Day”, a BBC documentary narrated by David AttenboroughIt will be released in the UK in April. In the United States, the PBS program “Nova” will air a version of the documentary next month.

When the object slammed into Earth, it hollowed out a crater about 100 miles wide and about 20 miles deep, with molten rock splashed into the air and cooled into glass spheres, one of the distinctive cards of meteor impacts. In a 2019 article, Mr. DePalma and colleagues described how globules raining from the sky clog and suffocate the gills of oars and sturgeons.

Often the outer parts of impact spheres have been mineralogically transformed by chemical reactions with water over millions of years. On Tanis, however, some descended on tree resin, which provides a protective amber casing and keeps them almost as pristine as the day they were formed.

In the most recent findings, yet to be published in a peer-reviewed scientific journal, Mr. DePalma and his research colleagues focused on unmelted rock fragments inside the glass.

“All these little dirty nuggets are there,” said Mr DePalma, a graduate student at the University of Manchester in England and an adjunct professor at Florida Atlantic University. “Every speck that moves away from this beautiful clear glass is a piece of debris.”

He said finding amber-covered orbs is equivalent to sending someone back in time to the day the impact occurred, “collecting a sample, bottling it, and keeping it for scientists right now.”

Most rock fragments contain high levels of strontium and calcium; this indicates that they were part of the limestone crust that the meteor had struck.

But the composition of the fragments within the two spheres “was wildly different,” said Mr. DePalma.

“They were not enriched with calcium and strontium as we expected,” he said.

Instead, they contained higher levels of elements such as iron, chromium, and nickel. This mineralogy points to the existence of an asteroid, and specifically a type known as carbonaceous chondrites.

“Seeing a piece of the criminal is just a chilling experience,” said Mr. DePalma.

Finding supports a discovery It was reported in 1998 by Frank Kyte., a geochemist at the University of California, Los Angeles. Dr. Kyte said he found a meteorite fragment in a drilled core sample in Hawaii, 5,000 miles from Chicxulub. Dr. The roughly one-tenth-inch-wide piece came from the impact event, Kyte said, but other scientists were skeptical that any part of the meteor could have survived.

“Actually, that fits with what Frank Kyte told us years ago,” said Mr. DePalma.

In an email, Dr. Kyte said it’s impossible to evaluate the claim without looking at the data. “I personally expect that if there is any meteoritic material in this ejecta, it will be extremely rare and unlikely to be found in large volumes of other ejecta in this region,” he said. “But maybe they were lucky.”

Mr. DePalma said that some of the spheres also appeared to have some bubbles inside. Since the spheres don’t appear to have cracked, it’s possible that they could hold fragments of air from 66 million years ago.

It would be fascinating to compare the Tanis fragments with samples collected by him, said Jim Garvin, chief scientist at NASA Goddard. NASA’s OSIRIS-REX mission, a spacecraft currently heading to Earth After visiting Bennu, a similar but smaller asteroid.

The latest techniques used to study space rocks, for example Newly opened samples from the Apollo missions 50 years agoIt can also be used in Tanis material. Dr. “They work perfectly,” Garvin said.

In the talk, Mr. DePalma also showed other fossil finds, including the well-preserved leg of a dinosaur identified as the plant-eating Thescelosaurus. “This animal was preserved to have these three-dimensional skin impressions,” he said.

There is no indication that the dinosaur was killed by a predator or by disease. This suggests that the dinosaur may have died on the day of the meteor impact, perhaps drowning in the floodwaters that drowned Tanis.

“It’s like a dinosaur CSI,” said Mr. DePalma. “Now as a scientist, I’m not going to say, ‘Yes, 100 percent, we have an animal that died in the pulse wave,'” he said. “It’s compatible? Yes.”

Neil Landman, honorary curator in the paleontology department at the American Museum of Natural History in New York, visited Tanis in 2019. He saw one of the oarfish fossils with globes in its gills and was convinced that the site indeed reflected his day. disaster and the aftermath. “This is the real deal,” he said in a phone call.

Mr. DePalma also showed images of a pterosaur embryo, a flying reptile that lived in the dinosaur era. Studies show that the egg is soft like that of modern lizards, and high calcium levels in the bones and the wing dimensions of the embryo. support existing research He said that reptiles can fly as soon as they hatch.

Paleontologist Steve Brusatte of the University of Edinburgh in Scotland, who served as a consultant on the BBC documentary, also believes the fish died that day, but is not yet sure that the dinosaur and pterosaur egg were also victims of the fish. effect.

“I haven’t seen any evidence of slam dunk yet,” he said in an email. “It’s a credible story but has yet to be proven beyond a reasonable doubt in the peer-reviewed literature.”

But the pterosaur embryo was still “an incredible discovery,” he said. Although skeptical at first, after seeing the photos and other information, she said, “It stunned me. To me, this may be Tanis’ most important fossil.”



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