Data from: When conifers took flight: A biomechanical evaluation of an imperfect evolutionary takeoff

Manifera talaris, a voltzian conifer from the late early to middle Permian (~270 Ma) of Texas, is the earliest known conifer to produce winged seeds indicative of autorotating flight. In contrast to autorotating seeds and fruits of extant plants, the ones of M. talaris are exceptional in that they have variable morphology. They bore two wings that produced a range of wing configurations, from seeds with two equal-sized wings to single-winged specimens, via various stages of underdevelopment of one of the wings. To examine the effects of various seed morphologies on aerodynamics and dispersal potential, we studied flight performance of paper models of three morphotypes symmetric double-winged, asymmetric double-winged, and single-winged. Using a high-speed camera we identified the mode of descent (plummeting, gliding, autorotation) and quantified descent speed, autorotation frequency, and other flight characteristics. To validate such modeling as an inferential tool, we compared descent of extant analogs (kauri; Agathis australis) to descent of similarly constructed seed models. All three seed morphotypes exhibited autorotating flight behavior. However, double-winged seeds, especially symmetric ones, failed to initiate slow autorotative descent more frequently than single-winged seeds. Even when autorotating, symmetric double-winged seeds descend faster than asymmetric double-winged ones, and descent is roughly twice as fast compared to single-winged seeds. Moreover, the relative advantage that (effectively) single-winged seeds have in slowing descent during autorotation becomes larger as seed weight increases. Hence, the range in seed wing configurations in M. talaris produced a wide variation in potential dispersal capacity. Overall, our results indicate that the evolutionarily novel autorotating winged seeds must have greatly improved conifer seed dispersal, at a time when animal vectors for dispersion were virtually absent. The early evolution of autorotative flight in conifers was a functionally imperfect one, which provides us insight into the evolutionary developmental biology of autorotative seeds in conifers.

塔拉里亚曼尼夫拉杉（Manifera talaris）是产自美国德克萨斯州早二叠世晚期至中二叠世（约2.7亿年，~270 Ma）的沃尔茨杉目（Voltziales）针叶树，也是目前已知最早产生可实现自旋飞行（autorotating flight）的带翅种子的针叶树。与现存植物的自旋式带翅种子和果实不同，该物种的种子形态极具特殊性：因其中一枚翅的发育程度存在差异，可形成多种翅型组合，从两枚翅大小均等的种子到仅具单翅的标本。为探究不同种子形态对空气动力学（aerodynamics）特性及传播潜力的影响，我们针对三类形态型（morphotypes）——对称双翅型、不对称双翅型及单翅型——的纸质种子模型开展了飞行性能测试。借助高速摄像机（high-speed camera），我们识别了种子的下落模式（垂直坠落、滑翔、自旋），并量化了下落速度、自旋频率及其他飞行特征参数。为验证该模型作为推断工具的有效性，我们将现存同类物种贝壳杉（*Agathis australis*，kauri）的种子下落行为与同构造方式的纸质种子模型的下落行为进行了对比。三类种子形态型均表现出自旋飞行行为，但双翅型种子（尤其是对称双翅型）相较于单翅型种子，更难启动缓慢的自旋下落过程。即便成功进入自旋下落状态，对称双翅型种子的下落速度也快于不对称双翅型种子，且约为单翅型种子的两倍。此外，（近似）单翅型种子在自旋下落时的减速优势会随种子重量增加而愈发显著。因此，塔拉里亚曼尼夫拉杉种子的翅型多样性使其传播潜力存在显著差异。综上，本研究结果表明，在动物传播媒介几乎缺失的地质时期，这种演化上全新的自旋式带翅种子极大地提升了针叶树种子的传播能力。针叶树自旋飞行的早期演化在功能上并非完美，这一发现为我们研究针叶树自旋式种子的演化发育生物学提供了重要视角。