North Dakota dig site could reveal answers about the day the dinosaurs died
A site near Bowman, North Dakota, has fossils revealing the last moments of the dinosaurs, wiped out millions of years ago. More findings from the site will be coming out.
FARGO — The discovery of jumbled fish and plant fossils preserved in a layer of mudstone on a badlands butte in southwestern North Dakota sent shock waves through the world of paleontology.
Uncovered in a remote area near Bowman, the discovery was announced in 2019 in a scientific journal describing the find as evidence of the catastrophic event that caused the extinction of the dinosaurs — an asteroid that struck the earth 66 million years ago.
In fact, the fossil site provided a geological snapshot that captured the very impact, when seismic waves produced by the asteroid strike traveled up a river valley, capturing “the day the dinosaurs died,” as some have put it.
Now, almost three years later, some scientists still are eagerly waiting for independent verification of the extraordinary findings from paleontologist Robert DePalma and his team, which made headlines around the world .
DePalma began his excavation of the site on private land in 2012 and has returned regularly, but no independent researchers have corroborated the team’s findings.
“The discoveries are stated to be so incredible we really need to see them to assess them,” said Denver Fowler, a paleontologist and curator of the Badlands Dinosaur Museum in Dickinson. “At the moment, I am really just waiting for the actual data to be published.”
Fossilized fish specimens that were collected at the site from a team of commercial paleontologists when the site was first discovered in 2008 could shed further light on the site, Fowler said.
“These specimens are a good control or opportunity for independent — and they must be truly independent — researchers to test the claims in the original publication" in which DePalma’s team reported their findings in a scientific journal, Fowler said.
Although Fowler has serious reservations about DePalma’s conclusions, he allows that they could be correct. “I would say it is right on the boundary of ‘plausible,’” he said, though he later added, “Very little evidence has been presented.”
DePalma told The Forum that more research findings from the site will be published later this year, from his team and possibly others, and work continues to gather and evaluate specimens.
“Work has been ongoing and research carried out since 2019 — and other studies initiated prior to that — are slated to start coming out in a steady stream,” he said.
Without revealing specifics before his research is published, DePalma said his team is focusing on “aspects of the rare biota” at the site as well as debris particles from the asteroid. Other teams are working on the geochemistry, sedimentology, plant and animal life as well as asteroid debris — work that, combined, will shed new light on the conditions when the dinosaurs died, he said.
Clint Boyd, senior paleontologist for the North Dakota Geological Survey, said his office has received inquiries from other scientists interested in the site, but so far access appears to be limited, possibly in keeping with the private landowner’s wishes.
“It’s been difficult for other people to independently verify the information coming out of this site,” Boyd said. “The greater the claim the more evidence we want to back it up.”
Actually, DePalma said, researchers from outside his team have visited the site, including from the American Museum of Natural History, Stony Brook University and European universities.
“Researchers outside of our team have visited the site nearly every dig season since work began, and/or continue to work on the material to this day,” he said, adding that he expects more such visits in the upcoming field season.
“One pleasantly surprising aspect of the project ever since it began was the constantly growing size of coauthors,” DePalma said. “Time after time, senior researchers were consulted for their outside opinions of the site and specimens, and they became so captivated by it that they often ended up joining us as coauthors.”
In an area not far from the site DePalma is examining, other researchers have found evidence of what scientists formerly called the K-T boundary and now call the K-Pg boundary, the earthen layer between the Cretaceous Period, when the large dinosaurs went extinct, and the Paleogene Period, when mammals began to flourish and evolve into larger species.
The site DePalma has made famous, which he calls Tanis after a lost Egyptian city, is within the Hell Creek Formation of Montana, North Dakota, South Dakota and Wyoming, where many dinosaur fossils have been found.
“It’s definitely in the right area for doing studies about the end of the Cretaceous,” the time of the last big dinosaurs, Boyd said.
Still, Boyd is withholding judgment about DePalma’s findings pending more information.
“I can’t make a determination either way, because I haven’t seen the evidence myself,” he said. “We haven’t been able to get out and look at the site.”
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The extinction of large dinosaurs from an asteroid impact was first proposed in the 1980s by father-and-son scientists Luis and Walter Alvarez.
The pair of researchers determined that a global layer of iridium, one of the rarest elements in the earth’s crust but commonly found in asteroids and meteorites, provided the telltale signature of a celestial body striking the earth at the time large dinosaurs went extinct.
But the discovery of the Tanis site is unique for purportedly capturing the mass deaths of marine life after the impact of the Chicxulub asteroid strike on Mexico’s Yucatán Peninsula.
The asteroid, with a diameter of more than six miles, slammed into the earth with the energy equivalent of more than 1 billion atomic bombs comparable to the one that destroyed Hiroshima. The impact, which created a crater 115 miles long and 12 miles deep, spewed millions of tons of debris into the atmosphere, further chilling a climate that already had begun to cool, with devastating consequences for the reptilian dinosaurs.
The asteroid impact also created a wave about a mile high that swept over a vast area. A tsunami from the asteroid strike likely would have taken more than 17 hours to reach Tanis, more than 1,800 miles away, DePalma concluded.
But his team calculated that seismic waves caused by the shock of the impact could have reached the area within “tens of minutes.”
Intriguingly, when DePalma first started working the site, he found fossils of freshwater and saltwater marine life, an indication of the tremendous chaos and power of the forces unleashed by the asteroid.
His explanation is that the force of the impact drove a wave of water up an ancient inland river valley, scooping up mud and sediment and depositing them to form the peculiarly tangled Tanis site.
In recently published research by separate teams, including one led by DePalma , scientists have determined that the mass die-off at Tanis happened during spring in the northern hemisphere, a time when plants in the subtropical Hell Creek Formation were flowering.
Another team that includes at least one member who has collaborated with DePalma soon after published similar findings , an unusual occurrence noted by the science journal Nature, which printed both studies in separate publications and an article examining the continued controversy over DePalma’s original research.
“The research came under intense scrutiny because no other site on Earth is thought to preserve a detailed record of the day of impact,” Nature reported. ”But many researchers note that the 2019 paper did not include a detailed description of the site’s geology, making it difficult to assess whether the geology can really be tied to the impact or another unknown catastrophe that occurred perhaps thousands of years earlier.”
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Perhaps in response to his early critics, in June 2019 DePalma and his colleagues published supplementary information about the analysis of sediment at the Tanis site in support of his findings.
A longtime associate who served as a field assistant for DePalma at the Tanis site said the work is well supported and noted one of DePalma’s research colleagues is Walter Alvarez, the younger half of the father-son team who made the link between the asteroid strike and the extinction of the dinosaurs.
DePalma and his colleagues have revisited the Tanis site regularly and continue to add to their findings, said Rudi Pascucci, director of the Palm Beach Museum of Natural History, where DePalma is curator and has done much of his laboratory work.
“They’ve worked every year on that,” he said. “They have a number of things going on.”
Glass-like beads found at Tanis have been compared to others found at a site in Haiti that has been linked to the Chicxulub asteroid, important evidence of the association, Pascucci said, adding, “They are a match."
DePalma will give a presentation at NASA’s Goddard Space Flight Center, “Identification of the Chicxulub Asteroid: the 'Smoking-Gun' that Slew the Cretaceous,” on April 6.
“Some of the new stuff he’s got coming out is exciting,” Pascucci said.
Tyler Lyson, a paleontologist and vertebrate curator at the Denver Museum of Nature and Science, is a native of Marmarth and has extensive experience scouring for fossils in the North Dakota Hell Creek Formation, where he found a hadrosaur fossil that included some skin and other soft tissue, “Dakota,” on his uncle’s ranch.
“We’re still sort of waiting to see additional data” from DePalma’s findings, he said. Lyson said he’s sympathetic to DePalma’s need to take time to analyze and publish his work, a process that can take years.
“It really is a spectacular claim,” he said. “With that, you need lots and lots of data.” The supplement to DePalma’s original paper was “very, very robust,” he added.
The Denver Museum of Nature and Science obtained a “block” from Tanis from the commercial fossil hunter who first found the site that contained five well-preserved fish skeletons. Lyson was looking for the glass beads associated with the asteroid strike and didn’t find any.
“If I opened up this block and saw a single spherule” — or glass bead — “I'd be convinced,” he said.
“But overall I’m excited about the discovery and I’m excited to see what else Robert and team publish,” Lyson said. “It’s going through the natural scientific process.”
DePalma said he’s not surprised Lyson’s sample didn’t contain any of the beads, which his team found by combing through material over a large area. He has found fish fossils with the spherules in their gills, he said.
Besides unearthing more information about the extinction of the dinosaurs, DePalma hopes the work at Tanis will yield insights into the effect of “global-scale impacts,” such as the asteroid strike.
He also hopes his work on the mass extinctions will support conservation efforts. “Stewardship of today’s life is essential,” DePalma said.