Researchers from UCL have found that dinosaurs’ apparent decline before the asteroid impact 66 million years ago was likely due to a poor fossil record, rather than genuine dwindling of dinosaur species. The study, published in Current Biology, analyzed the fossil record of North America over 18 million years up to the end of the Cretaceous period.
The team found that the quality of the fossil record for four groups of dinosaurs decreased during the final 6 million years prior to the asteroid impact. This suggests that the probability of finding dinosaur fossils decreases while the likelihood of dinosaurs having lived in these areas remains stable. The study’s findings contradict the long-held idea that dinosaurs were already experiencing a decline before their extinction.
The researchers used occupancy modeling to estimate how likely each species was to inhabit a particular area, and found that the proportion of land occupied by the four dinosaur types remained constant overall, suggesting their potential habitat area remained stable and risk of extinction low. However, they also found that the likelihood of detection declined over time due to factors such as accessibility of rock and researchers’ ability to find fossils.
The study’s lead author, Dr. Chris Dean, said, “We show that the apparent decline is more likely a result of a reduced sampling window, caused by geological changes.” The findings suggest that dinosaurs were not inevitably doomed to extinction and might still be alive today if it weren’t for the asteroid impact.
Source: https://phys.org/news/2025-04-dinosaurs-apparent-decline-prior-asteroid.html