After mass extinction, Earth’s ocean was Jurassic dead zone

A mass extinction event that wiped out the majority of the world’s creatures was made worse because the Earth’s ocean had almost no oxygen for thousands of years afterward. Scientists report in the journal Geochemistry Geophysics Geosystems that they studied rock formations to determine how much dissolved oxygen was in Earth’s prehistoric ocean about 200 million years ago. Their results suggest that life would have taken a long time to rebound after a mass extinction event commonly known as the end-Triassic extinction — which happened at the boundary between the Triassic and Jurassic periods — because of the low oxygen level. Read more.