Although the asteroid impact’s sudden alteration of the climate, and the related destruction of many of the world’s species, is also recorded in Seymour Island and elsewhere across the globe, this study confidently links preceding volcanism to a huge spike in extinction rates – but not quite enough to kill off the non-avian dinosaurs. Still, the fact that the volcanic activity’s effects reached as far as Antarctica is indicative of its immense and terrifying scale.
The authors point to a previous study, which claims that truly severe mass extinctions are often only possible when an impact occurs close to prolonged volcanic activity. Impacts are “pulse” disturbances that induce sudden environmental change, and effusive catastrophic volcanism is a “press disturbance" that takes time to have an effect.
"If you want to answer ‘what caused [this] mass extinction?’ we would say 'the press-pulse of the volcanism-impact co-occurrence,'" Petersen adds.
Importantly, though, there are two possible versions of events here: Either the volcanism did most of the damage, allowing the asteroid to seal the deal, or the asteroid was mostly responsible for the end-Cretaceous mass extinction event. The study points to the diverse fossil record at Seymour Island that seems to indicate that both antagonists were equally impactful in this regard, but their analysis on this point is inconclusive.
Interestingly, a recent study also based on the fossils from Seymour Island did not find any mass extinction die-off related to the Deccan Traps, and instead only found the extinction markers for the asteroid impact. The debate, therefore, is far from over – but malicious volcanic activity is once again back in the spotlight.
Mass murder, committed by volcanoes and an asteroid, seems likely to have happened 66 million years ago. Wead/Shutterstock