66 million years ago, at the end of the Cretaceous, the impact of an asteroid caused a massive extinction that ultimately caused the extinction of the dinosaurs along with 75% of the species on Earth. Now, a new study concludes that the recovery of life at the crash site was faster than previously thought.
The research, published in the Nature journal, was led by Christopher Lowery of the University of Texas (Austin, USA).
The impact of the asteroid, which fell into a shallow sea near Chicxulub, on the Mexican peninsula of Yucatan (Mexico), was so virulent that it left a crater 111 miles in diameter and significantly altered the entire geology of the Earth.
The power of the impact – equivalent to a billion atomic bombs – produced large earthquakes of magnitude greater than eleven on the Richter scale, giant waves (tsunamis) between 300 and 900 feet in height, temperature increases, fires at distances between 930 and 2,400 miles from the crater, and acid rain, among other catastrophes.
As a result, three out of four of the marine and continental species that lived in that period (the Phanerozoic) were extinguished, which led to a great change in the evolution of life on Earth.
So far it had been suggested that, after the catastrophe, the global marine ecosystem took about 300,000 years to recover in the areas near the impact site (the Gulf of Mexico and the North Atlantic), and that toxic metal pollution could have been the cause of the slow recovery in the crater zone.
This new study analyzed the rock samples obtained after the perforation of the Chicxulub crater, which conserve a record of the first 200,000 years after the impact. The examination of several tiny fossils – unicellular foraminifera with shell and nanoplankton – together with fossil traces of biological activity and abundant chemical elements, led to a surprising conclusion: life reappeared in Chicxulub just a few thousand years after the impact.
According to the authors of the work, the ecosystem of high marine productivity recovered in 30,000 years, a comparatively short geological time.
And although there was already evidence of this recovery in places like Spain, southern France, Italy or Tunisia, the study concludes that this recovery was also “immediate” in the area of impact, although the paleoenvironmental change was much more drastic.
The authors argue that ecological processes, such as interactions between organisms in the crater, probably controlled recovery.
“This recovery was even faster than in other areas farther from the impact and is the result of the important connection of the impact zone with open waters, which allows the rapid restoration of favorable conditions for the development of life,” researcher Rodriguez-Tovar explains.
Thus, the study highlights the importance of ecological processes to understand how ocean ecosystems respond to similar events of rapid extinction.