Bozeman, MT – Were dinosaurs already fading away before the asteroid hit 66 million years ago? A new study suggests the answer might be no—and the fossil record could be misleading us.
According to researchers from institutions including the University of Bristol and the University of Michigan, data bias—not actual dinosaur decline—may be responsible for the apparent drop in species diversity near the end of the Cretaceous. The study, published this month in Current Biology, used advanced occupancy modeling to reassess dinosaur fossil patterns across North America.
📌 Why This Matters
Helps us better understand whether dinosaurs were thriving or declining before their extinction
Suggests fossil record gaps might reflect geology—not biology
Introduces a new way to study extinction and evolution using statistical models
Scientists focused on four major dinosaur groups: ankylosaurs, hadrosaurs, ceratopsians, and tyrannosaurs. By comparing the raw fossil record with model-based estimates of where dinosaurs likely lived and could have been found, researchers found the apparent drop in diversity wasn’t due to dinosaurs disappearing—it was because fossils became harder to detect.
That’s largely due to shifting geology. The study points out that the areas with the best fossil preservation—like parts of Alberta and Montana—became less common over time. On top of that, today’s land cover (like forests or urban areas) makes it harder to uncover fossils in some places.
Detection rates were especially affected for armored dinosaurs like ankylosaurs and duck-billed hadrosaurs, while ceratopsians (like Triceratops) remained more visible in the record late into the Cretaceous.
The team’s modeling approach, often used in ecology and conservation, adds a new tool for paleontology—one that helps researchers factor in how land changes, erosion, and even roads might impact where we find fossils.
So, while dinosaurs did vanish suddenly 66 million years ago, this study suggests they weren’t already on their way out—it might just look that way because nature didn’t leave us all the evidence.
