Vast amounts of debris, soot, and aerosols shot into the atmosphere when an asteroid slammed into Earth 66 million years ago, plunging the planet into darkness, cooling the climate, and acidifying the oceans. Along with the dinosaurs on the land and giant reptiles in the ocean, the dominant species of marine algae were instantly wiped out, except for one rare type.
A team of scientists, including researchers at the University of California, wanted to understand how these algae managed to thrive while the mass extinction rippled throughout the rest of the global food chain.
To answer their questions, the team examined well-preserved fossils of the surviving algae and created detailed computer models to simulate the likely evolution of the algae's feeding habits over time. Their findings are now published in the journal Science Advances.
Scientists were a bit lucky to find the nano-sized fossils in the first place. They were located in fast accumulating and high-clay-content sediments, which helped preserve them in the same way the La Brea tar pits in Hancock Park provide a special environment to help preserve mammoths.
A high-resolution scan of the fossils' shells show that most of them contain calcium carbonate shields featuring holes, which indicate the presence of flagella- thin, tail-like structures that allow tiny organisms to swim and capture food particles.
The only reason you need to move is to get your prey. The researchers found that these mixotrophic algae expanded from coastal shelf areas into the open ocean where they became a dominant life form for the next million years, helping to quickly rebuild the food chain. It also helped that larger creatures who would normally feed on these algae were initially absent in the post-extinction oceans.
