By Sid Perkins
Widespread extinctions in the world’s oceans millions of years ago may have been triggered by massive underwater volcanic eruptions that created much of the Caribbean seafloor.
About 93.5 million years ago, many types of deep-sea creatures, including large clams and various microorganisms that lived on the seafloor, died out. At the same time, thick layers of organic-rich marine sediments accumulated at several sites worldwide, says Steven C. Turgeon, a geochemist at the University of Alberta in Edmonton.