Science finds traces of ‘winter’ that wiped out the dinosaurs

The study is the first to provide physical evidence for the sudden plunge in global temperatures that followed the impact off Mexico’s Yucatan Peninsula.

Its effects would have been identical to those of a “nuclear winter” – the chilling effect of dust blotting out the sun in the aftermath of a large-scale nuclear war.

According to the new research, the “Chicxulub” impact is likely to have lowered global sea surface temperatures by as much as 7C at a conservative estimate.

For creatures evolved to live in a lush, warm, green world, the result would have been catastrophic.

The “winter” is thought to have lasted no more than a number of decades, but that was enough to wipe out the dinosaurs, flying and swimming reptiles, and many other forms of life.

Only the most adaptable survived, leading to the reign of the birds and mammals that continues to this day.

The evidence comes from the Brazos River region of Texas, where sedimentary rocks the same age as the asteroid impact contain layers of broken shells.

They are thought to have been left there by a tsunami triggered when the massive space rock plunged into the ocean.

Unusually high concentrations of iridium produced as the asteroid vaporised are also found in the sediments.

An idea of post-impact sea surface temperatures was obtained by analysing fatty molecules from marine organisms preserved in the rocks. These had a different signature before and after the event.