Bug breath

 作者:还熘     |      日期:2019-03-07 03:06:20
AN oxygen-rich atmosphere allowed gigantic insects to grow 300 million years ago. Dragonflies with wingspans of up to 70 centimetres flourished in the Carboniferous period. Researchers had long suspected that the giant insects and lush forests needed more oxygen than the level of 21 per cent found in today’s atmosphere. Plants and marine life preferentially take up certain isotopes of carbon and sulphur and their absorption changes as the concentration of oxygen rises ( Science, vol 287,