Last updated June 7, 2018 at 2:37 pm
Drilling under the crater suggests ecological processes controlled recovery.
Plankton repopulate the Chicxulub Crater in the first years after the impact of the asteroid that caused the end Cretaceous mass extinction. Credit: John Maisano and University of Texas
Life recovered more rapidly than suspected at the site of the asteroid impact that wiped out the non-avian dinosaurs and more than 75 per cent of all other species 66 million years ago, according to new research from the US.
The asteroid hit the Earth in a shallow sea near Chicxulub, on Mexico’s Yucatán Peninsula.
As the global marine ecosystem recovered more slowly near the resulting crater than in areas further away (taking up to 300,000 years in the Gulf of Mexico and the North Atlantic), it had been suggested that an impact-related environmental effect, such as toxic metal poisoning, might have been responsible.
However, when researchers led by Christopher Lowery from the University of Texas Austin analysed rock samples drilled up from beneath the crater, which preserve a record of the first 200,000 years after the impact, they came up with a different view.
The team examined changes in various tiny fossils – the single-celled, shelled foraminifera and calcium-based nannoplankton – along with fossil traces of biological activity and the abundance of various elements, such as extra-terrestrially derived helium-3, the flux of which can be used to infer sedimentation rates.
These showed that life recovered at the crater mere years after the catastrophe, with a diverse and highly productive ecosystem returning to Chicxulub within 30,000 years — far more quickly than at sites further away from the impact. The findings suggest there was no impact-related control on recovery.
Instead, the authors propose, ecological processes such as the interactions between organisms in the crater probably controlled recovery, highlighting the importance of such in understanding how ocean ecosystems respond to similar rapid extinction events.
The paper published in Nature.
