Plankton turned hunters to survive dinosaur-killing asteroid impact

After the last global mass extinction, 66 million years ago, most of the plankton that survived were those able to capture food to eat, according to a study led by UCL and University of Southampton researchers. The findings, published in Science Advances , support the theory that darkness drove the global extinctions, after an asteroid impact, as plankton and plants would not have been able to use photosynthesis to get their energy from the sun. Co-lead author Professor Paul Bown (UCL Earth Sciences) said: "We found that before the dinosaurs went extinct, plankton were similar to modern-day plankton as they got their energy directly from the sun - but that all changed very suddenly." "After a massive asteroid strike, most of the plankton that persisted used a different survival strategy, by hunting and ingesting food. "Our findings add to a growing body of evidence that the last global mass extinction was driven by a global darkness, and was probably the only truly geologically instantaneous mass extinction event." The research team used an exceptional record of plankton fossils and eco-evolutionary modelling techniques to examine how organisms behaved before and after this event, which killed three quarters of life on earth - and why some survived and some didn't. The team found that prior to the asteroid impact, species of nannoplankton - microscopic algae - were exclusively reliant on harnessing energy from sunlight ( photoautotrophs) , but those living afterwards were capable of capturing food and eating it in addition to using photosynthesis to feed ( mixotrophs) .