A new Stanford University study shows rising oxygen levels may explain why global extinction rates slowed down over the past 541 million years. Below 40 percent of present atmospheric oxygen, ocean dead zones rapidly expand, and extinctions ramp up.
Stanford-led expeditions to a remote area of Yukon, Canada, have uncovered a 120-million-year-long geological record of a time when land plants and complex animals first evolved and ocean oxygen levels began to approach those in the modern world.
The geological sciences PhD student has been awarded a Graduate Research Fellowship from NSF to explore marine invertebrate body size changes in the fossil record.
