nosaurs vanished 65 million years ago, hit by factors such as expanding cities, farms, pollution and climate change.Perrings said studies might be, for instance, of the impacts of stricter world trade rules to try to slow a spread of insect pests, or of the effects on nature of setting aside more cropland to produce biofuels.BIOFUELSIn recent years, efforts to promote biofuels had often fallen sho