Collision in asteroid belt influenced life on Earth
WASHINGTON: The 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 yesterday dust spawned by a gigantic collision in the asteroid belt 400 million years earlier triggered an ice age on Earth that ushered in an increase in marine biodiversity.
The event, occurring when life was concentrated in the seas, 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 dust after an asteroid more than 150km in diameter was struck by a smaller object perhaps 20km wide, they said, in the solar system’s largestknown breakup event in the past 2 billion years.
Solar radiation reaching Earth’s surface was reduced for at least 2 million years by the dust, study coauthor Philipp Heck, of the Field Museum in Chicago, said.
Another cooling mechanism was that the ironrich meteoritic dust fertilised the ocean surface, leading to increased plankton productivity and drawdown of atmospheric carbon dioxide, added Birger Schmitz, of Lund University in Sweden, lead author of the research.
The researchers found traces of dust in sedimentary rocks formed at the time containing helium isotopes and rare minerals that revealed its extraterrestrial origin.
Invertebrate groups that experienced diversification included trilobites, clams, brachiopods and gastropods.
The cooling event unfolded gradually, enabling marine life during the Ordovician Period to adaptas Earth’s climate changed from being tropical to semitropical worldwide, to being divided into climate zones, as it is today. — Reuters