Mass Extinction Not so Bad for Plankton?

An artist's impression of a giant space rock slamming into Earth 65 million years ago near what is now Mexico's Yucatan Peninsula. A consortium of scientists now says this was indeed what caused the end of the Age of Dinosaurs. (Image credit: NASA/Donald E. Davis)

Many marine plankton species went extinct during the mass die-off of the dinosaurs 65 million years ago. The worldwide rain of tiny dead shells littered marine sediments from the period.

But at least one plankton-eating animal appears to contradict this evidence of a mass plankton extinction, a new study reports. Fossil records of coral-like marine creatures called bryozoans, which survived the killer asteroid impact, show little change across the extinction boundary. The bottom-dwelling animals live in colonies, either erect on the seafloor or encrusted on other organisms such as seaweed. Bryozoan's feather-like filters catch passing plankton and other food particles as they drift past.