Science / Medicine : Oxygen Saturation in Dinosaur Era Disputed

Studies purporting to show that the Earth’s atmosphere contained 50% more oxygen during the time of the dinosaurs are wrong, researchers reported last week. The original claim was made by researchers from Yale University and the U.S. Geological Survey, who analyzed air that they said had been trapped in amber--yellow-colored, fossilized resin from trees--some 80 million years ago.

But four different groups of researchers reporting independently in Science magazine said the researchers overlooked the ability of amber to absorb gases. Chemical engineer Harold Hopfenberg of North Carolina State University and entomologist George O. Poinar Jr. of UC Berkeley found experimentally that gases could readily diffuse into and out of amber.

Hopfenberg noted that textbooks show that oxygen is more soluble than other gases in amber and similar solids, so that one would expect to find a higher proportion of oxygen in amber than in air. In fact, the percentage of oxygen in amber, 35%, predicted from its known solubility is precisely what the Yale and USGS researchers found. “The story’s over,” he said.