New data reconstructions of ocean temperatures dating back to the end of the age of dinosaurs support the theory that dinosaurs went extinct thanks to both an asteroid impact and volcanic eruptions.
A pair of researchers from the University of Michigan and their colleague from Florida discovered not one but two ocean temperature warming spikes in the Antarctic that were roughly in line with a pair of extinction “pulses” documented previously and dating back to the final years of the Cretaceous Period around 66 million years in the past. The first of these pulses has been associated with a massive round of volcanic eruptions that occurred in what is modern-day India, while the second is thought to be from a comet or asteroid impact off the coast of the Yucatan Peninsula in Mexico.
Each of these events was accompanied by a period of ocean temperature warming, the researchers found, after a chemical analysis of fossilized shells from the period. Using a new technique, known as the carbonate clumped isotope paleothermometer, the scientists were able to show that ocean temperatures in the Antarctic increased by around 14 degrees Fahrenheit during the initial warming event. The rising temperatures were likely due to large quantities of carbon dioxide gas entering the atmosphere as a result of the string of volcanic eruptions – something that would have increased atmospheric temperatures thanks to the ability of CO2 to trap heat. It would be around 150,000 years before the next spike in the fossil record, around the time of the cataclysmic Yucatan Impact. This later spike was smaller than the earlier one, however.
According to a report in ScienceDaily, the new temperature data helps forge a direct link between volcanic activity and impact events regarding extinction pulses, with climate change being that link. The mass extinction that occurred at the end of the Cretaceous was the result of not just the volcanic activity or the asteroid impact but both.