The cataclysmic asteroid impact off Mexico’s coast that doomed the dinosaurs 66 million years ago was not the only time an astronomical event shaped the history of life on Earth.
Scientists said that dust spawned by a gigantic collision in the asteroid belt between Mars and Jupiter 400 million years earlier triggered an ice age on Earth that ushered in a significant increase in marine biodiversity.
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The event, occurring when life was concentrated in the seas and far before vertebrates first walked on land, set in motion evolutionary changes in invertebrates fundamental to marine ecosystems as they adapted to global cooling, they said.
The inner solar system was filled with enormous amounts of dust after an asteroid more than 150 km in diameter was struck by a smaller object perhaps 20 km wide, the researchers said. It was the solar system’s largest-known breakup event in the past 2 billion years.
The researchers found traces of dust in sedimentary rocks formed at the time containing special helium isotopes and rare minerals that revealed its extraterrestrial origin.
Invertebrate groups that experienced diversification included horseshoe crab-like trilobites, clams, clam-like brachiopods and a group called gastropods that included snails and slugs.
The cooling event unfolded gradually, enabling marine life during the Ordovician Period to adapt, unlike the sudden impact that erased the dinosaurs. Earth’s climate changed from being tropical to semitropical worldwide to becoming divided into climate zones as it is today with frozen poles and tropical conditions at the equator.