That picture (below) comes in the form of a “timetree”—a phylogenetic tree that not only shows how species are related, but also when each split occurred in evolutionary history. The idea is ...

Thus, understanding the evolutionary history of living species amounts to understanding where on the tree of life these species' distinctive traits arose. Moreover, phylogenetic trees serve as ...

Image usage restrictions: News organizations may use or redistribute this image, with proper attribution, as part of news coverage of this paper only. The backscatter ...