Royal Academy of Sciences, Madrid, Spain; Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA, USA; Area of Paleontology, Faculty of Sciences, Universidad de Malaga, Malaga, Spain.
Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA, USA.
Curr Biol. 2021 Apr 26;31(8):R370-R372. doi: 10.1016/j.cub.2021.03.058.
Feathered dinosaurs discovered during the last decades have illuminated the transition from land to air in these animals, underscoring a significant degree of experimentation in wing-assisted locomotion around the origin of birds. Such evolutionary experimentation led to lineages achieving either wing-assisted running, four-winged gliding, or membrane-winged gliding. Birds are widely accepted as the only dinosaur lineage that achieved powered flight, a key innovation for their evolutionary success. However, in a recent paper in Current Biology, Pei and colleagues disputed this view. They concluded that three other lineages of paravian dinosaurs (those more closely related to birds than to oviraptorosaurs) - Unenlagiinae, Microraptorinae and Anchiornithinae - could have evolved powered flight independently. While we praise the detailed phylogenetic framework of Pei and colleagues and welcome a new attempt to understand the onset of flight in dinosaurs, we here expose a set of arguments that significantly weaken their evidence supporting a multiple origin of powered flight. Specifically, we maintain that the two proxies used by Pei and colleagues to assess powered flight potential in non-avian paravians - wing loading and specific lift - fail to discriminate between powered flight (thrust generated by flapping) and passive flight (gliding).
在过去几十年中发现的有羽毛恐龙，阐明了这些动物从陆地到空中的过渡，强调了在鸟类起源时，翅膀辅助运动方面进行了大量的实验。这种进化实验导致了谱系实现了翼辅助奔跑、四翼滑翔或膜翼滑翔。鸟类被广泛认为是唯一实现动力飞行的恐龙谱系，这是它们进化成功的关键创新。然而，在最近发表在《当代生物学》上的一篇论文中，Pei 及其同事对这一观点提出了质疑。他们得出结论，三个其他的近鸟类恐龙谱系（比 Oviraptorosauria 更接近鸟类的谱系）-Unenlagiinae、Microraptorinae 和 Anchiornithinae-可能已经独立进化出了动力飞行。虽然我们赞赏 Pei 及其同事详细的系统发育框架，并欢迎他们尝试理解恐龙飞行的起源，但我们在这里提出了一系列论点，这些论点极大地削弱了他们支持动力飞行多起源的证据。具体来说，我们认为 Pei 及其同事用来评估非鸟类近鸟类动力飞行潜力的两个代理指标-翼载荷和特定升力-无法区分动力飞行（拍打产生的推力）和被动飞行（滑翔）。
