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She was struck by the fact that one of the conifer species produced a range of seed shapes, ranging from single-winged to asymmetrical and symmetrical double-winged seeds This is unusual, she says, because the single-winged seeds have the clear advantage of enhanced dispersal efficiency, especially during the Permian when seed dispersal by animals was virtually absent.Even more unusual was the fact that different conifer species that independently evolved whirling, or autorotating, seeds ended up with only one optimal seed shape up in today’s conifer species.

At the time, most plant life consisted of lycopods, ferns, horsetails, and seed ferns, with a few of the first cone-bearing trees, like conifers and cycads, appearing.Looy studied these fossils when she worked as a postdoctoral researcher at the Smithsonian Institution from 2004 to 2008, and was struck by the seed variety within a single species compared to today.[related] “In these conifers you can see steps from making winged seeds to making autorotating seeds.Moreover, the difference in flight performance of single-winged whirling seeds and asymmetrical or symmetrical double-winged ones increased with increased seed weight or in turbulent air.Looy, former research assistant Robert Stevenson, and former graduate student Dennis Evangelista, now at the University of North Carolina at Chapel Hill, report their findings in 270 million-year-old fossils from Texas show that early conifers produced a variety of winged seeds to aid dispersal by the wind.

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