Dinosaur-Killing Mass Extinction Was Due To Combined Effects Of Volcanic Eruptions And Asteroid Impact

Researchers from the University of Michigan analyzed the Antarctic Ocean temperatures during the dinosaur mass extinction 66 million years ago. It showed that the cause of the mass extinction of the non-avarian dinosaurs and about three-quarters of the planet's plant and animal species was due to the combined effects of volcanic eruptions and an asteroid impact.

Sierra Petersen, a postdoctoral researcher in the U-M Department of Earth and Environmental Sciences explained that this new temperature record gives a direct link between the volcanism and impact events and the extinction pulses--that link being climate change. She further explained that they discover that the end-Cretaceous mass extinction was caused by a combination of the meteorite impact and volcanism, delivering a theoretical 'one-two punch,' as noted by Science Daily.

The study was printed online in the journal Nature Communications on July 5, 2016. In the study, the researchers found two unexpected warming spikes in ocean temperatures that agree with the two past documented extinction pulses near the end of Cretaceous Period. These include the first extinction pulse, which has been tied to massive volcanic eruptions in India and the second extinction, which was caused by the impact of an asteroid on Mexico's Yucatan Peninsula. The team analyzed the chemical composition of fossil shells using the new technique called the carbonate clumped isotope paleothermometer.

Petersen said that the new record of ancient Antarctic Ocean temperatures gives strong support for the press-pulse extinction mechanism. She further said that the pre-impact climate warming due to volcanism may have increased ecosystem stress. This makes the ecosystem vulnerable to collapse when the meteorite hit.

The Cretaceous Period continued about 79 million years, from the minor extinction that ends the Jurassic Period about 145.5 million years ago to the Cretaceous-Paleogene (K-Pg) extinction event seen at 65.5 million years ago.

The end of Cretaceous ended the diverse groups of organism. These include the ammonites and the non-avarian dinosaurs. This Cretaceous Period was thus the time in which life as it currently exists on Earth emanated together.