Asteroids play a god-like role in the story of life on Earth. But our planet's relationship with flying space rocks doesn’t always take a destructive form, like the notorious asteroid that wiped out the dinosaurs 66 million years ago. A new study has suggested that a gigantic boom of biodiversity on Earth that occurred around 470 million years ago could all be thanks to a cataclysmic collision in the asteroid belt.
Around 466 million years ago, Earth embarked on one of the most monumental explosions of biodiversity in its history, in what’s now referred to as the Great Ordovician Biodiversification Event (GOBE). During this event, marine biodiversity saw a spectacular increase, mostly within the phyla established during the Cambrian Explosion, the period most major animal phyla popped up in the fossil record some 541 million years ago. The GOBE eventually paved the way for the evolution of green algae, primitive fish, cephalopods, corals, and a bunch of other creatures we would recognize today.
Reporting in the journal Science Advances, scientists from Lund University in Sweden argue that this event was sparked by a collision in the asteroid belt somewhere between Mars and Jupiter involving a 150-kilometer-wide (93 miles) asteroid.
As per their hypothesis, dust flung out from the crash blocked a significant quantity of sunlight from reaching Earth, causing temperatures to plummet and a mini ice age to arise. In the process of adapting to the new climate – chillier but more suitable for life – a high diversity of invertebrates arose.
"Our results show for the first time that such dust at times has cooled Earth dramatically. Our studies can give a more detailed, empirical-based understanding of how this works, and this, in turn, can be used to evaluate if model simulations are realistic," Birger Schmitz, professor of geology at Lund University and leader of the study, explained in a statement.
The team reached this conclusion by studying the composition of petrified seafloor sediments in Kinnekulle, southern Sweden. The presence of an isotope of helium and other substances trapped in the sediments can only be explained by the solar wind having bombarded the dust, enriching it with those elements before it crashed down to Earth.
"This result was completely unexpected. We have during the last 25 years leaned against very different hypotheses in terms of what happened. It wasn't until we got the last helium measurements that everything fell into place," said Schmitz.