In June 2021, paleontologist Melanie During submitted a manuscript to Nature that she suspected might create a minor scientific sensation. Based on the chemical isotope signatures and bone growth patterns found in fossilized fish collected at Tanis, a renowned fossil site in North Dakota, During had concluded the asteroid that ended the dinosaur era 65 million years ago struck Earth when it was spring in the Northern Hemisphere.
But During, a Ph.D. candidate at Uppsala University (UU), received a shock of her own in December 2021, while her paper was still under review. Her former collaborator Robert DePalma, whom she had listed as second author on the study, published a paper of his own in Scientific Reports reaching essentially the same conclusion, based on an entirely separate data set. During, whose paper was accepted by Nature shortly afterward and published in February, suspects that DePalma, eager to claim credit for the finding, wanted to scoop her—and made up the data to stake his claim.
After trying to discuss the matter with editors at Scientific Reports for nearly a year, During recently decided to make her suspicions public. She and her supervisor, UU paleontologist Per Ahlberg, have shared their concerns with Science, and on 3 December, During posted a statement on the journal feedback website PubPeer claiming, “we are compelled to ask whether the data [in the DePalma et al. paper] may be fabricated, created to fit an already known conclusion.” (She also posted the statement on the OSF Preprints server today.)
The plotted line graphs and figures in DePalma’s paper contain numerous irregularities, During and Ahlberg claim—including missing and duplicated data points and nonsensical error bars—suggesting they were manually constructed, rather than produced by data analysis software. DePalma has not made public the raw, machine-produced data underlying his analyses. During and Ahlberg, a member of the Royal Swedish Academy of Sciences, question whether they exist.
DePalma, now a Ph.D. student at Manchester University, vehemently denies any wrongdoing. “We absolutely would not, and have not ever, fabricated data and/or samples to fit this or another team’s results,” he wrote in an email to Science. He says the study published in Scientific Reports began long before During became interested in the topic and was published after extended discussions over publishing a joint paper went nowhere. “Ultimately, both studies, which appeared in print within weeks of each other, were complementary and mutually reinforcing,” he says.
The raw data are missing, he says, because the scientist who ran the analyses died years prior to the paper’s publication, and DePalma has been unable to recover them from his deceased collaborator’s laboratory.
Several independent scientists consulted about the case by Science agreed the Scientific Reports paper contains suspicious irregularities, and most were surprised that the paper—which they note contains typos, unresolved proofreader’s notes, and several basic notation errors—was published in the first place. Although they stopped short of saying the irregularities clearly point to fraud, most—but not all—said they are so concerning that DePalma’s team must come up with the raw data behind its analyses if team members want to clear themselves.
“Something is fishy here,” says Mauricio Barbi, a high energy physicist at the University of Regina who specializes in applying physics methods to paleontology. “It needs to be explained. … If they can provide the raw data, it’s just a sloppy paper. If not, well, fraud is on the table.”
“The bottom line is that this case will just involve bluster and smoke-blowing until the authors produce a primary record of their lab work,” adds John Eiler, a geochemist and isotope analysis expert at the California Institute of Technology.
However, two independent scientists who reviewed the data behind the paper shortly after its publication say they were satisfied with its authenticity and have no reason to distrust it.
The chief editor of Scientific Reports, Rafal Marszalek, says the journal is aware of concerns with the paper and is looking into them. He declined to share details because the investigation is ongoing.
The most phenomenal site
During visited Tanis in 2017, when she was a master’s student at the Free University of Amsterdam. Her mentor there, paleontologist Jan Smit, introduced her to DePalma, at the time a graduate student at the University of Kansas, Lawrence. DePalma holds the lease to the Tanis site, which sits on private land, and controls access to it.
Part of the phenomenally fossil-rich Hell Creek Formation, Tanis sat on the shore of the ancient Western Interior Seaway some 65 million years ago. When the dino-killing asteroid struck Earth, shock waves would have caused a massive water surge in the shallows, researchers say, depositing sedimentary layers that entombed plants and animals killed in the event.
During and DePalma spent 10 days in the field together, unearthing fossils of several paddlefish and species closely related to modern sturgeon called acipenseriformes. “I’ve done quite a few excavations by now, and this was the most phenomenal site I’ve ever worked on,” During says. “There was a fossil everywhere I turned.”
After she returned to Amsterdam, During asked DePalma to send her the samples she had dug up, mostly sturgeon fossils. He did so, and later also sent a partial paddlefish fossil he had excavated himself. During obtained extremely high-resolution x-ray images of the fossils at the European Synchrotron Radiation Facility in Grenoble, France. The x-rays revealed tiny, crystalized bits of glass called spherules—remnants of the shower of molten rock that would have been thrown from the impact site and rained down around the world. (DePalma and colleagues published a paper in the Proceedings of the National Academy of Sciences in 2019 that described finding these spherules in different samples analyzed at another facility.)
The fact that spherules were found in the fishes’ gills suggested the animals died in the minutes to hours after the impact. But the fossils also held clues to the season of the catastrophe, During found. A thin layer of bone cells on sturgeons’ fins thickens each spring and thins in the fall, providing a kind of seasonal metronome; the x-rays revealed these layers were just beginning to thicken when the animals met their end, pointing to a springtime impact. And mass spectrometry revealed the paddlefish’s fin bones had elevated levels of carbon-13, an isotope that is more abundant in modern paddlefish—and presumably their closely related ancient relatives—during spring, when they eat more zooplankton rich in carbon-13.
During described the findings in her 2018 master’s thesis, a copy of which she shared with DePalma in February 2019. That same year, encouraged by a Dutch award for the thesis, she began to prepare a journal article. Over the next 2 years, During says she made repeated attempts to discuss authorship with DePalma, but he declined to join her paper. Still, when During submitted her manuscript to Nature on 22 June 2021, she listed DePalma as the study’s second author.
DePalma characterizes their interactions differently. He says his team came up with the idea of using fossils’ isotopic signals to hunt for evidence of the asteroid impact’s season long ago, and During adopted it after learning about it during her Tanis visit—a notion During rejects. After his team learned about During’s plan to submit a paper, DePalma says, one of his colleagues “strongly advised” During that the paper must “at minimum” acknowledge the team’s earlier work and include DePalma’s name as a co-author. DePalma says his team also invited During’s team to join DePalma’s ongoing study. “During the long process of discussing these options … they decided to submit their paper,” he says.
DePalma submitted his own paper to Scientific Reports in late August 2021, with an entirely different team of authors, including his Ph.D. supervisor at the University of Manchester, Phillip Manning. “No part of During’s paper had any bearing on the content of our study,” DePalma says. Science asked other co-authors on the paper, including Manning, for comment, but none responded.
Manual transcription process
When DePalma’s paper was published just over 3 months later, During says she soon noticed irregularities in the figures, and she was concerned the authors had not published their raw data. Ahlberg shared her concerns. At his suggestion, she wrote a formal letter to Scientific Reports. She also removed DePalma as an author from her own manuscript, then under review at Nature.
In a 6 January letter to the journal editor handling his manuscript, which he forwarded to Science, DePalma acknowledged that the line graphs in his paper were plotted by hand instead of with graphing software, as is the norm in the field. He says he did so because the isotopic data had been supplied as a “non-digital data set” by a collaborator, archaeologist Curtis McKinney of Miami Dade College, who died in 2017. DePalma also acknowledged that the “manual transcription process” resulted in some “regrettable” instances in which data points drifted from the correct values, but “none of these examples changed the overall geometry of the plotted lines or affected their interpretation.” McKinney’s “non-digital data set,” he says, “is viable for research work and remains within normal tolerances for usage.”
Miami Dade does not have an operational mass spectrometer, suggesting McKinney would have had to perform the isotope analyses underlying the paper at another facility. But McKinney’s former department chair, Pablo Sacasa, says he is not aware of McKinney ever collaborating with laboratories at other institutions. “I don’t believe that Curtis himself went to another lab, he was ill for many years,” Sacasa says.
Asked where McKinney conducted his isotopic analyses, DePalma did not provide an answer. He did send Science a document containing what he says are McKinney’s data. It features what appear to be scanned printouts of manually typed tables containing the isotopic data from the fish fossils. These tables are not the same as raw data produced by the mass spectrometer named in the paper’s methods section, but DePalma noted the data’s credibility had been verified by two outside researchers, paleontologist Neil Landman at the American Museum of Natural History and geochemist Kirk Cochran at Stony Brook University.
Both Landman and Cochran confirmed to Science they had reviewed the data supplied by DePalma in January, apparently following Scientific Reports’s request for additional clarification on the issues raised by During and Ahlberg immediately after the paper’s publication. Cochran says the format of the isotopic data does not appear unusual. “‘Raw machine data’ are seldom supplied to end users (myself included) who contract for isotope analyses from a lab that does them.”
Cochran says DePalma erred in not including these data and their origins in his original manuscript, but “the ‘bottom line’ is that I have no reason to distrust the basic data or in any way believe that it was ‘fabricated.”
Eiler disputes this. If the data were generated in a stable isotope lab, “that lab had a desktop computer that recorded results,” he says, and they should still be available. “Those files were almost certainly backed up, and the lab must have some kind of record keeping process that says what was done when and by whom.”
Barbi is similarly unimpressed. “They seem to have left the raw data out of the manuscript deliberately,” he says. “In my view, it was an intentional omission which leads me to question the credibility of data.” Steve Brusatte, a paleontologist at the University of Edinburgh, says, “There is a simple way for the DePalma team to address these concerns, and that is to publish the raw data output from their stable isotope analyses.”
On 2 December, according to an email forwarded to Science, the editor handling DePalma’s paper at Scientific Reports formally responded to During and Ahlberg for the first time, During says. The email, which came after Science started to inquire about the case, says their concerns remain under investigation.
The response doesn’t satisfy During and Ahlberg, who want the paper retracted. Eiler agrees. “If I were the editor, I would retract the paper unless [the raw data] were produced posthaste,” he says. It is “certainly within the rights of the journal editors to request the source data,” adds Mike Rossner, an independent scientist who investigates claims of biomedical image data manipulation. “And, if they are not forthcoming, there are numerous precedents for the retraction of scholarly articles on that basis alone.”
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