Paleontologists are getting a glimpse at life over a billion years in the past based on chemical traces in ancient rocks and the genetics of living animals. Research published Dec. 1 in Nature Communications combines geology and genetics, showing how changes in the early Earth prompted a shift in how animals eat.
Modern birds and mammals are “warm-blooded” or endothermic, maintaining a constant body temperature and generating heat internally, while reptiles rely on heat from their surroundings. It has been known for some time that at least some dinosaurs, including the direct ancestors of modern birds, were also endotherms.
