Located in Canada’s Gulf of Saint Laurence, Anticosti Island is home to one of the world’s richest deposits of fossils and sedimentary rock, dating back some 445 million years, a time known as the end of the Ordovician period.
Located in Canada’s Gulf of Saint Laurence, Anticosti Island is home to one of the world’s richest deposits of fossils and sedimentary rock, dating back some 445 million years, a time known as the end of the Ordovician period. Like the pages of a mystery novel, these layers of limestone gradually reveal the secrets of over 15 million years of life on Earth. By studying samples from this fossil record, researchers recently made a discovery that sheds light on one of paleontology’s great questions: the causes of the first mass extinction of animal life.
Research conducted by an international team of scientists, drawn from the University of Ottawa, the University of New Mexico, and the University of Birmingham, shows that the mass extinction of marine life that took place at the end of the Ordovician was triggered by marine anoxia, a drop in seawater oxygen levels that causes marine animals to asphyxiate.
“Up until now, we suspected that marine anoxia had played a role in the mass extinction that followed a period of global cooling,” says Professor André Desrochers of the Faculty of Science, University of Ottawa. “By analysing samples of the marine limestone taken from Anticosti Island, we were able to show that a sharp drop in oxygen levels in the oceans eliminated up to 85% of all animal life on Earth at that time.”
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Image via University of Ottawa.
