The extinction of dinosaurs might be down to “colossal bad luck,” a new study has found. After examining an up-to-date fossil record, scientists believe that had the asteroid collision that fuelled their demise happened a little earlier or later, they may have been able to survive. While that may sound disappointing to some, we should thank our lucky stars as if they hadn’t been wiped out, we probably wouldn’t be here today.
Dinosaurs became extinct some 66 million years ago, with the exception of avian dinosaurs whose descendants live among us today in the form of birds. This mass extinction event, known as K-T (Cretaceous-Tertiary), wiped out around 70% of species present at the time. While there has been some debate over the cause of the extinction, it's generally accepted that a catastrophic impact from a huge asteroid or comet that slammed into Mexico is to blame. Support for this idea came from radiometric dating that suggested these two events occurred no more than 33,000 years apart.
The collision left a ginormous crater some 124 miles wide and 12 miles deep in the Yucatan peninsula. Not only that, but it would have triggered tsunamis, earthquakes and huge fires, changed global temperatures and cloaked the Earth with debris that impeded photosynthesis, thus disrupting food chains. In sum: it was a devastating event, but scientists now believe that had it occurred at a “more convenient time,” the dinosaurs may have prevailed.
To come to this conclusion, a team of researchers led by the University of Edinburgh scrutinized new data collected over the past two decades in order to paint a picture of dinosaur diversity during the latest Cretaceous. They were interested in unveiling any changes that occurred over the few million years prior to the impact that could have contributed to the mass extinction.
In the paper, which has been published in Biological Reviews, the researchers share a few key findings. Before K-T took place, the Earth was experiencing dramatic environmental changes including increased volcanic activity, changes in global temperatures and rising sea levels. This likely resulted in the observed reduction in biodiversity among large herbivores, which would have had knock-on effects on the big predatory species. This unfortunate series of events left many species vulnerable and thus particularly susceptible to the changes that ensued after the collision took place.
“The dinosaurs were victims of colossal bad luck,” lead author Steve Brusatte said in a news-release. “Not only did a giant asteroid strike, but it happened at the worst possible time, when their ecosystems were vulnerable.”
The researchers suggest that if the impact had taken place a few million years earlier, when food chains were more stable due to greater biodiversity, then in all likelihood they would have survived. Similarly, if it had bombarded the Earth a few million years later, it’s likely that herbivores would have had a chance to recover and thus ecosystems would have been more settled and better equipped to withstand changes.
“Although our research suggests that dinosaur communities were particularly vulnerable at the time the asteroid hit, there is nothing to suggest that dinosaurs were doomed to extinction,” said co-author Richard Butler. “Without that asteroid, the dinosaurs would probably still be here, and we very probably would not.”
[Header image, "Last of the Plum Island Dinosaurs," by Russ Seidel, via Flickr. Used in accordance with CC BY-NC-ND 2.0]