Researchers have retrieved samples of 1.4 billion-year-old air from ancient crystals and found something surprising about a supposedly “boring” time period. The team studied the gases and fluids locked in halite crystals (rock salt) from Canada, shedding light on the composition of the atmosphere hundreds of millions of years before dinosaurs walked the Earth. It turns out the planet was sporting more oxygen than expected—at least, in that exact moment in time—as they explained in a study published last month in PNAS. Direct samples of air “The carbon dioxide measurements Justin obtained have never been done before,” Rensselaer Polytechnic Institute’s...