The mass extinction event at the end of the Cretaceous Period — about 65 million years ago — that killed the dinosaurs was sudden and just as deadly to marine life in Antartica, finds new research.
Previously, scientists had thought that organisms living near the poles were far enough away from the cause of the extinction to be badly affected — whether this was an asteroid impact in the Gulf of Mexico, where a giant buried impact crater is found today, or extreme volcanism in the Deccan volcanic province in India.
“Even the animals that lived at the ends of the Earth close to the South Pole were not safe from the devastating effects of the mass extinction at the end of the Cretaceous Period,” said one of the researchers, Jane Francis from British Antarctic Survey.
For the study, published in the journal Nature Communications, the team involved a six-year process of identifying more than 6,000 marine fossils ranging in age from 69- to 65-million years old.
The enormous collection, excavated by scientists on Seymour Island in the Antarctic Peninsula, included a wide range of species, from small snails and clams that lived on the sea floor, to large and unusual creatures that swam in the surface waters of the ocean.
“Antarctic rocks contain a truly exceptional assemblage of fossils that have yielded new and surprising information about the evolution of life 66 million years ago,” Francis said.
With the fossils grouped by age, the collection shows a dramatic 65-70 percent reduction in the number of species living in the Antarctic 66 million years ago, coinciding exactly with the time when the dinosaurs and many other groups of organisms worldwide became extinct at the end of the Cretaceous.
“This is the strongest evidence from fossils that the main driver of this extinction event was the after-effects of a huge asteroid impact, rather than a slower decline caused by natural changes to the climate or by severe volcanism stressing global environments,” lead study author James Witts, doctoral student at University of Leeds in Britain, said.