Ancient conifer provides example of winged-seed evolution

New Scientist : As early as 370 million years ago, conifer trees began to develop seeds with two wings, which enabled the seeds to catch the wind and travel farther from the parent tree. Over the next 100 million years, the seeds evolved to have just a single wing. Cindy Looy and Robert Stevenson of the University of California, Berkeley, caught a glimpse of that evolution in action through their study of one of the earliest known such conifers, Manifera talaris. Based on fossil evidence, they created paper models of the three known seed types—symmetric double-winged, asymmetric double-winged (with one large and one small, stunted wing), and single-winged. The researchers found that the single-winged seeds, which adopted an autorotating, helicopter-style spin, remained airborne the longest, and that the asymmetric double-winged seeds flew farther than the symmetric double-winged seeds.