How deep-sea creatures survived dinosaur-killing asteroid

LONDON: Scientists have solved the mystery behind how deep sea creatures managed to survive the catastrophic asteroid strike that wiped out the dinosaurs 65 million years ago.

Like the dinosaurs themselves, giant marine reptiles, invertebrates and microscopic organisms became extinct after the asteroid impact in an immense upheaval of the world's oceans, yet deep sea creatures managed to survive.

This has puzzled researchers as it is widely believed that the asteroid impact cut off the food supply in the oceans by destroying free-floating algae and bacteria.

However, a team led by researchers from Cardiff University in the UK provides strong evidence suggesting that some forms of algae and bacteria were actually living in the aftermath of the asteroid disaster, and that they acted as a constant, sinking, slow trickle of food for creatures living near the seafloor.

The team was able to draw these conclusions by analysing new data from the chemical composition of the fossilised shells of sea surface and seafloor organisms from that period, taken from drilling cores from the ocean floor in the South Atlantic.

This gave the researchers an idea of the flux, or movement, of organic matter from the sea surface to the seafloor in the aftermath of the asteroid strike, and led them to conclude that a slow trickle of food was constantly being delivered to the deep ocean.

Researchers were able to calculate that the food supply in the ocean was fully restored around 1.7m years after the asteroid strike, which is almost half the original estimates, showing that marine food chains bounced back quicker than originally thought.

"The global catastrophe that caused the extinction of the dinosaurs also devastated ocean ecosystems. Giant marine reptiles met their end as did various types of invertebrates such as the iconic ammonites," said Heather Birch, a Cardiff University PhD, who led the study.