J. John Sepkoski Jr., a paleontologist who charted the diversity of ocean life through Earth's history, died Saturday of sudden heart failure. He was 50.
"Paleobiology is a small profession, so when we lose one of our very greatest, it's really a tremendously painful experience," said Harvard University paleontologist Stephen Jay Gould in a statement released today by the University of Chicago. "Jack was one of the leading lights of the profession."
Sepkoski compiled massive data sets on the diversity of marine organisms over the last 600 million years. Sepkoski developed a set of statistical tools for combing through the data, enabling him and others to discover broad patterns in evolution and extinction.
During the 1980s, Sepkoski and Chicago colleague David Raup put forth the controversial theory that catastrophic extinctions of marine animals may have occurred approximately every 26 million years during the past 250 million years of Earth's history. The theory helped raise the possibility that mass extinctions--on land as well as in the seas--may result from catastrophic comet and asteroid impacts.