The sun hung high over the badlands of New Mexico when Dr. Daniel Peppe crouched over a patch of rock. It was the aftermath of the COVID-19 pandemic, and Peppe, associate professor of geosciences at Baylor University, was hard at work on a long-running project. With careful, practiced sweeps, he brushed away the layers of sediment that sat atop the rock. The fossils beneath his fingers held part of a secret that would dramatically change our understanding of the dinosaurs that preceded us.
Here, in a cruel, sun-smacked expanse of the western U.S., Peppe, his students, and colleagues discovered that dinosaurs had not, in fact, been on the decline before that fateful asteroid struck the Earth.
Rather, they thrived until the very end.
Origins of a groundbreaking project
Peppe’s path to those badlands began years earlier, as an undergraduate studying in North Dakota. While researching how ecosystems react to shifts in their environment, he learned how to read the patterns left behind by plant life and, in turn, reconstruct climates of the distant past. His research affirmed the idea that ecosystems don’t collapse overnight — they evolve in complex ways, responding to shifts in climate and to each other.
While earning his Ph.D., he turned his focus to the asteroid strike that wiped out non-avian dinosaurs.
“It’s a big extinction of dinosaurs and other animals, but it’s also a pretty large extinction in plants,” Peppe said. “And so, during that work, I built this long-term climate record.”
He was able to see how species reacted to extinction in northern North America, but he wanted to see if ecosystems in the south reacted the same way. This interest ultimately led to Peppe partnering with researchers from New Mexico State University, the Smithsonian Institution, and a host of other universities, as well as a pack of talented Baylor Bears. The group sought further clarity on the long-gestating debate about whether dinosaurs were already on the decline before that fateful asteroid, and to this task, each member of the team contributed key pieces to the research puzzle: There were fossil plant experts, talented decoders of geological data, and seasoned radiometric analysts.
Peppe described the project as “a collaborative effort,” and that collaboration led to a vital discovery now published in the esteemed journal Science.
Using high-precision techniques to date the fossils they found, Peppe and his team found that it really was the asteroid, not long-term decline, that led to the extinction of the dinosaurs.
Many, many years in the making
The first samples were collected in 2011, and from those initial excursions, the team began to piece together a record of southern North America that would eventually stretch across millions of years and rewrite the narrative of extinction.
Many of the conversations happened not in the laboratory or over Zoom, but around campfires in the field, where ideas could be tested, debated, and reshaped.
As Peppe recalled, “We were able to conclusively date this unit, and once we did that, we were like, ‘Oh, that means the dinosaurs have to be a lot younger than everyone has been saying they are.’”
For the professor, one of the most exciting discoveries came from the work of Andrew Flynn, a student who joined as a master’s candidate and found fossil leaves in locations where the research team had yet to discover anything.
Because Flynn collected more than enough data than was necessary for his initial effort, he was able to use his work on the project to start work toward a Ph.D. It was a chance for a young Bear to gain invaluable experience on a major project, and for Peppe, it was a chance to help a student follow their curiosity and let a project grow in an unexpected direction — similar to how they grew for the young Peppe.
As Peppe explained, “That’s what’s been really a fun thing for me with my students. We sort of go where the questions take us and then figure out the path to get there.”
“Baylor and my lab were a really integral part of this,” he added. “A lot of this was funded by grants that I had, but some of this was also funded by the geoscience department at Baylor, and the students were supported as teaching assistants for part of their time during their PhDs and their masters. All of that together was really influential in helping us make this study happen.”
Read more: Owen Lind and the Birth of Environmental Studies at Baylor
Together, Peppe and Flynn mapped fossil plants, geological formations, and radiometric dates. They compared ecosystems across time and space, discovering more about ancient provinces in the north and the south. Rather than collapsing uniformly in response to catastrophe, these communities maintained distinct patterns shaped by climate. Peppe found this remarkable.
“After the extinction event, we saw that northern and southern biotic provinces that existed before the extinction continued through the extinction,” he said. “It suggests that intrinsic evolutionary and speciation and migration events are influencing community response.”
The work was not without its challenges. Field seasons were unpredictable, and the team weathered snowstorms and sudden downpours that transformed the terrain into mud. Then there was the pandemic, which abruptly halted progress in 2020. Yet these interruptions were part of the iterative process that defined the project. Each setback offered a chance to refine methods, revisit assumptions, and rebuild momentum. Peppe described the years after the pandemic as a period of “reinvigoration.”
“Overall, it was a really fun project,” he said. “Every summer we would go out and collect data, come back to the lab, and multiple times we’d get results that told us we needed to collect more data and put it all together.”
Understanding the past to understand the future
The implications of their findings ripple through paleontology. For years, some researchers had argued that dinosaurs were already declining, a community primed for extinction even before the asteroid struck. The work of Peppe and his colleagues tells a different story, which challenges both the assumptions about the end of the Cretaceous and the narrative that extinction was inevitable. If the asteroid had never arrived, some species might have persisted longer than anyone had imagined.
The work is also not yet done.
“I’m really interested to see what patterns we see in other continents as more data comes online,” Peppe said.
The research invites collaboration, not conflict, and opens doors for future studies that could expand understanding of dinosaur ecology across the globe.
Looking ahead, Peppe’s curiosity has already turned to the next layer of questions. He wants to understand how life rebounded after extinction and how plants and mammals responded. Early evidence suggests that some mammal communities changed rapidly, possibly influenced by subtle shifts in forest structure rather than climate alone. The team is also investigating a short-lived warming event a few million years after the extinction that may have triggered shifts in both plant and mammal populations. Each discovery provides more clarity about our past — and some insight about our future, too.
Studying past mass extinctions, Peppe explained, can help us understand the risks facing our world today. Even thriving ecosystems can collapse suddenly when a tipping point is crossed.
“By looking at these extinction events in the past, it helps us contextualize what’s happening today, and what could happen today,” Peppe said.
