The theory of the role of "double impact" in triggering mass extinctions is supported by the participation of volcanoes in the extinction of dinosaurs.
The main reason for the disappearance of ancient lizards is considered to be the fall of an asteroid. But it was rather the last straw that triggered the processes of the Cretaceous-Paleogene extinction. Other factors also acted against the dinosaurs, significantly weakening them by the time the celestial body appeared. One of them is called volcanism - the eruption of the vast Deccan traps in the west of modern India. On the other hand, more recently, geologists have shown that this activity was not enough for dangerous climate change on a global scale.
To further confuse the story, new work by scientists led by Kyger Lohmann from the University of Michigan threatens. Judging by the results they published in the journal Nature Communications, it's too early to discount volcanoes. According to the authors, neither the asteroid nor volcanism in themselves were powerful enough to cause such catastrophic changes across the planet. But together they were enough.
Scientists analyzed the oxygen isotopic composition of the fossilized shells of the Late Cretaceous period, which survived on Seymour Island off the coast of Antarctica. This is a good indicator of the temperature at which the sediments formed, so the shells bore accurate evidence of catastrophic warming during the extinction of the dinosaurs.
Judging by these data, since the beginning of the eruption of the Deccan Traps, about 66.28 million years ago, the amount of carbon dioxide in the atmosphere began to constantly and noticeably increase. This led to a global rise in temperature by an impressive 7.8 ° C and the beginning of the mass extinction of species. There are also traces of an asteroid impact in the fossils - more precisely, a sharp climatic jump, which developed after relatively slow changes as a result of volcanic activity.
The authors believe that these results support the growing belief in the need for a "double whammy" to trigger mass extinctions: high volcanic activity creates constant pressure, and the fall of a large celestial body delivers the final blow.
