The atmosphere of Earth during the Mesozoic era, between 252 and 66 million years ago, contained far more carbon dioxide than it does today and total photosynthesis from plants around the world was twice as high as it is today, according to an analysis of oxygen isotope composition of dinosaur teeth. The fossilized teeth of Camarasaurus from the Morrison Formation in the United States. Image credit: Sauriermuseum Aathal. In the study, Dr. Dingsu Feng...