A recent study has provided new insights into how life rebounds from mass extinctions, challenging prevailing theories. Researchers from the University of Chicago, the Smithsonian Institution, and the Natural History Museum in London analyzed fossilized clams and mussels to understand ocean ecosystems before and after the mass extinction event 66 million years ago. Despite three-quarters of species being lost, each ecological niche remained occupied.
David Jablonski, a professor at UChicago and one of the study's authors, noted that this finding is "a really interesting, and slightly disquieting" revelation. The research suggests that while significant numbers of species perished, ecological roles persisted. Co-author Katie Collins highlighted that it was "extremely statistically unlikely" for all niches to remain filled despite such extensive species loss.
The study questions existing models on biodiversity recovery post-extinction. Traditionally, scientists believed major extinctions either accelerated inevitable changes or allowed survivors to evolve into new niches. However, neither model fully aligns with these findings.
Jablonski described this as "a bit of a wakeup call," emphasizing the need to better understand how functional group losses relate to biological diversity loss. The research also found unexpected patterns in species recovery post-extinction.
Stewart Edie explained that survival didn't guarantee dominance later on; instead, recovery was "scrambled." This contradicts assumptions that survivors would rapidly diversify following an extinction event.
The findings have implications for modern conservation efforts. Jablonski stressed the importance of understanding these dynamics in managing current threats like ocean acidification and overfishing. He stated that effective management should consider broader ecological structures rather than focusing solely on individual species.
The study titled “The end-Cretaceous mass extinction restructured functional diversity but failed to configure the modern marine biota” was published in Science Advances on May 21, 2025. It received funding from organizations including the National Science Foundation and NASA.