Details of the study
The evidence from the Triassic-Jurassic extinction was gathered at two sites in the Queen Charlotte Islands, off the coast of British Columbia.
Samples from two spots showed a sharp decline in the presence of organic carbon, the researchers said. The organic carbon decline correlated with a decline of one-celled organisms called radiolarians, which serve as a food source for a number of marine species.
"These provide the best record of how nasty the extinction was at this boundary [in time]," Ward said.
The mass extinction occurred just before the breakup of Pangea, which contained all the land on Earth in one supercontinent. At the time, the Queen Charlotte Islands -- which now lie between 52 and 54 degrees north latitude -- were thought to sit at the equator or in the Southern Hemisphere.
"These are tropical fossils," Ward said. "There are many kinds of fossils in these rocks."
With a NASA astrobiology grant in hand, Ward and colleagues plan to go back to the islands this summer to look for more evidence of the extinction and potential causes.
Others involved in the study include James Haggart and Howard Tipper of the Geological Survey of Canada, Elizabeth Carter of Portland State University and University of Washington researcher David Wilbur and student Tom Evans.
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