It’s almost 40 years since scientists discovered what wiped out the dinosaurs: an asteroid hitting Earth near modern-day Mexico. That was it, or so we thought.
A new paper published in Science further supports an alternative hypothesis: that catastrophic events following the impact could have helped cause the end of the dinosaurs and many other forms of life.
This builds on earlier work – including some published last year – suggesting a connection between the asteroid impact, increased volcanic eruptions, and the mass extinction event.
In it, they outlined evidence of a global catastrophe, buried in a layer spread all over the planet, about 66 million years ago.
They found high levels of iridium – a rare element in Earth’s crust, but common in meteorites. They found shocked quartz – grains of quartz with telltale fractures from the blast wave of the impact, as well as evidence of molten rock thrown out from the impact blast.
The reign of the dinosaurs ended with a meteorite impact, marking the end of the Cretaceous, and start of the Paleogene period, called the K-Pg boundary.
Was there something else?
Yet within the Earth science community, discontent continued to simmer.
Two of the largest mass extinctions in the geological record both coincide with the largest exposed continental flood basalt events in the past 542 million years. They are the end of the Permian 251 million years ago, and – as today’s Science paper highlights – the dinosaur extinction at the end of the Cretaceous 66 million years ago.
The coincidence seems too great.
In understanding the link between flood volcanism, meteorite impacts and extinctions, timing is everything.
In the new Science paper, a team from the United States and India present some of the most precise dates yet for the enormous eruptions in India, in a unit known as the Deccan Traps – an enormous flood basalt province in Western India that covers more than 500,000km2 and in places is more than 2km thick.