Evolution: Striking out asteroid role in diversity explosion

One of the most important increases in marine diversity to have occurred in the history of life on the Earth cannot be linked to meteorite bombardment as previously thought according to a new study published in Nature Communications this week.

The Great Ordovician Biodiversification Event (GOBE) represents an explosion in global marine animal and plant life diversification and a major evolutionary step for life on Earth, which started around 471 million years ago. The initiation of the GOBE has been previously linked to the start of an intense meteorite bombardment event of the Earth that was believed to have occurred around the same time.

Anders Lindskog and colleagues dated zircon crystals from meteorite-bearing sediments in Sweden and compared them with published cosmic-ray exposure ages of associated meteoritic material to show that meteorite bombardment started at around 468 million years ago. This new age indicates that the initiation of the GOBE actually preceded the start of the intense meteorite bombardment event of the Earth by at least two million years.

This research rules-out meteorite bombardment as the cause of the initiation of the GOBE, thereby reopening the question of what was the cause of the explosion in diversification of marine life at this time?