Kerry Howley writes:

It remains a matter of dispute when and where and with what antecedent Melanie During came up with the idea for determining the season the asteroid killed the dinosaurs. But the idea was this: Sturgeon bones grow like tree rings, and the bone cells grow thickest in summer, when food is most plentiful. A slice of bone, then, should reveal a succession of seasons. Months of plenty would be thicker, as the fish grew fat on plankton. The outermost bone, the last stage of bone growth before the asteroid, should reveal the season of death.

During had a single year to finish her master’s thesis after her 2017 visit to Tanis [in South Dakota], and she did not have the money to extend the time. If she did not finish the thesis, she would not graduate and would not be able to apply to Ph.D. programs. “When people tell you ‘Relax,’ I’m like, What’s that? ” she told me. “What do you mean? Do I sit down and do nothing?”

She was not an expert in fossil fish, or histology, or the Late Cretaceous; she had learned isotope-analysis methodology only the previous year from her adviser, Jeroen van der Lubbe. She was a few years out of undergrad — not even a doctoral student. The demise of the non-avian dinosaurs is perhaps the best-known division in all of paleontology, a historical moment that reaches beyond the classroom into childhood nurseries. It is constituent of the way our culture structures the history of the universe, basic to the way we have come to categorize time itself. For a Dutch 20-something to believe she would contribute new information regarding this moment in a master’s thesis was potentially delusional, but During felt the fish from Tanis contained long-hidden knowledge the right methods might evoke.

Her first attempt to measure the growth lines was a failure, four months lost on a faulty technique. “It was a waste of my time to continue,” she says. “I don’t cry over spilled milk.” She had to beg and wheedle for equipment; she was expert in very little but unafraid to ask for help. In order to understand the chemical composition of her samples, she needed to understand what was the original bone and what was a chemical artifact of the process of fossilization. To do that required a Micro XRF spectrometer, which she did not have, but a friend in Brussels had access to one; she drove to Brussels, and there, for the first time, she clearly saw the growth lines in slices of bone.

During’s naïveté would be, over and over, her strength. She intended to measure the isotopic ratio between two molecules at different points in the growth lines. In a university building that still stands only because there is a nuclear reactor in the basement, in a room with a window taped against the wind, During positioned and repositioned a tiny slice of fish bone in a micromill. She came into the little room before dawn and left when it was dark. “You’re still here,” the lab manager, Suzan Warmerdam-Verdegaal, would say on her way out of the building. The mill produced specks of fossil, smaller than a grain of sand. One day, after she had labored for many hours to collect a few samples, a colleague opened the door. The samples wafted into the room, lost to her. That day, she did cry.

A bit of luck: At a dinner for During’s partner on the occasion of his doctoral defense, another scientist with connections to the European Synchrotron Facility offered her some time there — a valuable and vanishingly rare opportunity for a young academic. She told DePalma, and he mailed her a fish skull. She brought the skull to an 844-meter tunnel for speeding electrons, and shot through it beams of light a million times brighter than the sun. The scan revealed the interior and inside the gills, incredibly, little bits of trapped clay: spherules that had traveled from the Yucatán to space and fallen back to Earth to be inhaled by a doomed paddlefish. [Continue reading…]