A new study led by Stanford University has found that rather than evolving gradually, land plants evolved in two dramatic bursts which occurred over 250 million years apart. The first burst occurred early in plant evolution (420 million to 360 million years ago), giving rise to the development of seeds. The second burst was characterized by the emergence of flowers, and started only about 100 million years ago. “The most surprising thing is this kind of stasis, this plateau in complexity after the initial evolution of...