dinosaur asteroid
July 28, 2014

Was Bad Luck The Real Reason Dinosaurs Became Extinct?

redOrbit Staff & Wire Reports - Your Universe Online

Dinosaurs were victims of bad timing, and likely would have survived the asteroid impact that wiped them out had it occurred slightly earlier or later, researchers from Edinburgh University report in a new study.

Dr. Steve Brusatte of the university’s School of GeoSciences and his colleagues explained that dinosaurs were at their most vulnerable when the asteroid hit, as a rising sea level and an increase in volcanic activity made them more susceptible to extinction, said BBC News science correspondent Pallab Ghosh. Had the impact occurred a few million years sooner or later, they might have survived.

Dr. Brusatte told Ghosh that it was simply a case of “colossal bad luck,” adding that the impact and the events leading up to it were “a perfect storm of events that occurred when dinosaurs were at their most vulnerable.” He was joined on the study by a team of 11 paleontologists and dinosaur experts from the US, UK and Canada.

Using the latest fossil records and improved analytical tools, the researchers found that the Earth started experiencing a tremendous environmental upheaval in the millions of years before the 10km-wide asteroid struck what is now Mexico. Increased temperature variability and other factors weakened the dinosaurs’ food chain, causing a lack of diversity among the large plant-eaters preyed upon by other dinosaurs.

When the asteroid crashed into the Earth, it would have caused a series of catastrophic events, including tsunamis, earthquakes and wildfires, as well as sudden temperature swings and other environmental changes. As the food chains started to collapse, one species of dinosaur after another would have died off as a result.

The only dinosaurs that would have survived these conditions would have been those with the ability to fly. However, had the asteroid hit a few million years earlier, when there was a more diverse group of species and a stronger food chain (or later after new species would have been able to evolve) they believe that the dinosaurs might have lived.

“Five million years earlier dinosaur ecosystems were much stronger, they were more diverse, the base of the food chain was more robust and it was harder to knock out a lot of species," Dr. Brusatte told BBC News. “If they had a few million years more to recover their diversity they would have had a better chance of surviving the asteroid impact. Dinosaurs… had plenty of dips and troughs in their diversity but they always recovered.”

While Ghosh noted there is “evidence that some species of dinosaur were dying off shortly before an asteroid hit the Earth,” raising the question that “this gradual decline would have led to the extinction of these animals even if the asteroid had not hit,” Dr. Brusatte’s team found that there was no evidence of a long-term decline during this time.

Of course, had they not died out when they did, the study authors told the BBC that there was no evidence that they would have survived until the present day. Other types of animals would have been more likely to developed human-like intelligence and learn how to create tools, which Dr. Brusatte said would undoubtedly have led to their demise.

Dr. Richard Butler of the University of Birmingham School of Geography, Earth and Environmental Sciences, who was a member of the research team, disagrees. He said that while their findings indicate that “dinosaur communities were particularly vulnerable at the time the asteroid hit, there is nothing to suggest that dinosaurs were doomed to extinction. Without that asteroid, the dinosaurs would probably still be here, and we very probably would not.”

Their study, published in Biological Reviews, was supported by the US National Science Foundation and the European Commission.