Scientists have long debated the theories of the cause of the largest of the known mass extinctions of Earth with more than 95% of marine species becoming extinct. New research led by the University of St Andrews and renowned German research centres helps answer one of the most asked questions in geoscience: what exactly caused the Earth’s biggest mass extinction?
The team of researchers, led by University of St Andrews’ Dr Hana Jurikova, used a novel analytical approach of different isotopes of the elements boron and carbon, retrieving the pH of the ancient ocean from fossil brachiopod shells. Although numerous brachiopod species also became extinct during the Great Dying, the team found brachiopod shells within the critical time interval which offered a snapshot of the rapid onset of the extinction. Seawater pH is a critical indicator that not only records ocean acidity, which varies depending on the amount of absorbed carbon dioxide (CO2), but together with carbon isotope constraints it also allowed the team to determine changes in the amount and sources of atmospheric CO2 at the time of the extinction event.