UC Berkeley researchers have discovered new evidence linking an asteroid impact to the extinction of the dinosaurs.

UC Berkeley Professor Paul Renne and a team of researchers, using isotope analysis, have found that both an asteroid impact and the extinction of the dinosaurs took place nearly synchronously 66 million years ago.

Previous studies have suggested that the impact and mass extinction took place at a delay of anywhere from 32,000 to 300,000 years.

“There is no question that the impact occurred, and there is no question that the impact occurred at the end of the dinosaurs and the beginning of new kinds of life,” Renne said.”I think it’s foolish to dismiss it as coincidence, but it’s not the whole story. It’s just the final blow.”

Renne and his team compared earth samples from northeastern Montana – a region containing dinosaur fossils – with earth samples from the Chicxulub crater in the Yucatan Peninsula, the site of an asteroid impact. Using isotope dating analysis, the researchers calculated with immense precision that the date of both the extinction of the dinosaurs and the asteroid impact were nearly the same.

But concerns have arisen over the validity of Renne’s findings due to potential problems with his methodology. Renne’s study relies heavily on land deposits, which may inappropriately disregard the marine record.

“Their interpretations go well beyond what can be supported by their data,” said Gerta Keller, a professor in the Department of Geosciences at Princeton University, in an email. “There is no age calibration with the marine record, yet all their interpretations are for the marine record.”

Other factors such as climate change or volcanic activity may have also contributed to the decline of the dinosaurs. One leading theory suggests that the eruption of the Deccan volcanoes – located in India  – polluted the atmosphere, leading to the dinosaurs’ end.

“It’s been a really difficult challenge to date that volcanism really precisely, and it just requires a serious effort with having the right kinds of samples,” Renne said. “It’s going to take a fair amount of work, but I’m confident that we can do a lot better than what has been done.”

Over the course of history, each mass extinction has been explained by volcanic eruptions, according to Renne. These new findings, however, suggest that other factors were involved with the mass extinction of the dinosaurs.

“We now have a much clearer idea of what happened in the past,” said UC Berkeley graduate student Bill Mitchell, who worked on the study. “If we don’t understand the timeline, we won’t understand the effects.”