It wasn’t just about the impact of a huge asteroid on Earth some 65 million years ago at the end of the Cretaceous. New research carried out by the universities of Michigan and Florida (United States) has determined that the disappearance of the dinosaurs was associated with two combined events: volcanic eruptions and the impact of an asteroid.
The researchers, using a new technique, with a model of past temperature in the Antarctic Ocean and the analysis of fossils in the same area, observed that the first extinction cycle at the end of the Cretaceous period could be related to huge volcanic eruptions in the region of Deccan Traps (India). On the other hand, the second extinction cycle was linked to the impact of a huge meteorite in the Chicxulub area , in the Mexican Yucatan peninsula, in the passage between the Cretaceous and the Paleogene.
The examination of the fossils was based on the chemical composition of fossilized shells by means of a novel technique called grouped carbonate isotope paleothermometer with which they were able to more accurately calculate the changes that occurred in the temperature of the water, which revealed that the temperatures of the The Antarctic Ocean rose about 14 degrees Fahrenheit during the first of these two events, caused by the heat released in the volcanic region and the second, smaller, around 150,000 years later, associated with the Chicxulub impact, in Yucatán.
According to the researchers, both events would be responsible for their disappearance: the first event, unbalancing the ecosystem (making it more vulnerable) and the second, definitively ending them with a new temperature peak on the surface. The link between the two events is climate change.
The study has been published in the journal Nature.
