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 (ca. 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 the 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 analogues (kauri; Agathis australis) with 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 improved conifer seed dispersal, in a time when animal vectors for dispersion were virtually absent. Because of the range in wing configuration, 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.

塔利拉里杉（Manifera talaris）是一种产自美国德克萨斯州早二叠世晚期至中二叠世（约2.7亿年前）的沃尔茨杉目（Voltziales）针叶树，是目前已知最早产生具有自旋飞行特征带翅种子的针叶树。与现生植物的自旋种子和果实不同，塔利拉里杉的种子具有独特的形态变异性：其种子拥有两枚翅，通过其中一枚翅的不同发育程度，可形成从双翅等大到单翅的一系列翅型组合。为探究不同种子形态对空气动力学特性与传播潜力的影响，我们针对三种形态型（对称双翅型、不对称双翅型与单翅型）的纸质模型开展了飞行性能测试。借助高速摄影机，我们识别了种子的下落模式（垂直坠落、滑翔与自旋飞行），并量化了下落速度、自旋频率等多项飞行特征参数。为验证该模型作为推断工具的有效性，我们将现生类比类群新西兰贝壳杉（Agathis australis）的种子下落行为与同结构的纸质模型进行了对比。三种种子形态型均表现出自旋飞行行为。但双翅型种子，尤其是对称双翅型种子，启动慢速自旋下落的成功率显著低于单翅型种子。即便进入自旋状态，对称双翅型种子的下落速度也快于不对称双翅型种子，且下落速度约为单翅型种子的两倍。此外，随着种子重量增加，（近似）单翅型种子在自旋下落时的减速优势会进一步扩大。因此，塔利拉里杉种子翅型的多样性，使其传播能力存在显著差异。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，演化上全新的自旋带翅种子显著提升了针叶树种子的传播效率。由于翅型存在多样性，针叶树自旋飞行的早期演化并非完美的功能形态，这为我们理解针叶树自旋种子的演化发育生物学提供了重要视角。