Data from: Additional information on the primitive contour and wing feathering of paravian dinosaurs

Identifying feather morphology in extinct dinosaurs is challenging due to dense overlapping of filaments within fossilized plumage and the fact that some extinct feather morphologies are unlike those of extant birds or those predicted from an ‘evo-devo’ model of feather evolution. Here, we compare a range of dinosaur taxa with preserved integumentary appendages using high-resolution photographs to better understand fossil feather morphology and gain insight into their function and evolution. A specimen of the basal paravian Anchiornis possesses contour feathers disarticulated from the plumage, revealing a novel feather type: a ‘shaggy’, open-vaned, bifurcated feather with long barbs attached to a short rachis, which is much simpler than the contour feathers of most extant birds. In contrast, it is likely that the contour feathers of Sinosauropteryx were simpler than those seen in Anchiornis; a ‘tuft’ morphology of multiple barbs connected at their bases (e.g. via a shared follicle), but lacking a rachis, is tentatively inferred. However, conclusive morphological descriptions await the discovery of isolated Sinosauropteryx contour feathers. Paravian wing feathers also show potentially plesiomorphic traits. Comparison with Confuciusornis suggests that Anchiornis wing feathers were at least partially open-vaned. Combined with the interpretation of Anchiornis contour feathers, this suggests that differentiated barbicels are relatively derived compared to pennaceous feathers and the appearance of wings. ‘Shaggy’ contour feathers probably influenced thermoregulatory and water repellence abilities, and, in combination with open-vaned wing feathers, would have decreased aerodynamic efficiency. Simplified, open-vaned wing feathers were also observed on the oviraptorosaur Caudipteryx, consistent with, but not necessarily diagnostic of, its suggested flightlessness. Taken together, these observations have broad implications for how we depict a wide variety of dinosaurs and how we view the function and evolution of feathers.由于化石羽毛内部的丝状体密集重叠，且部分已灭绝恐龙的羽毛形态与现生鸟类截然不同，亦不符合羽毛演化的‘进化发育学(evo-devo)’模型所预测的形态，因此识别已灭绝恐龙的羽毛形态极具挑战。本研究通过高分辨率影像，对一批保存有皮肤衍生物的恐龙类群开展对比分析，以期更深入地解析化石羽毛的形态特征，并揭示其功能与演化机制。 一件基底副鸟类的近鸟龙(Anchiornis)标本带有从整体羽毛中分离出的廓羽，展现出一种全新的羽毛类型：一种‘蓬松凌乱’、具开放羽片的分叉羽毛，其长羽枝附着于短羽轴之上，相较于多数现生鸟类的廓羽结构更为简单。 与之相对，中华龙鸟(Sinosauropteryx)的廓羽结构很可能比近鸟龙更为简单：研究人员暂推断其呈现‘羽簇’形态——多根羽枝在基部（如通过共享毛囊）相连，但缺乏羽轴。不过，要得到确凿的形态学描述，仍有待发现单独保存的中华龙鸟廓羽标本。 副鸟类的翼羽同样展现出潜在的祖征性状。通过与孔子鸟(Confuciusornis)的对比可知，近鸟龙的翼羽至少部分具备开放羽片结构。结合近鸟龙廓羽的相关解读，这一结果表明，分化的羽小枝相较于闭合羽片羽毛以及翼结构的形成而言，属于相对衍生的特征。 这种‘蓬松凌乱’的廓羽可能对体温调节与防水能力产生了影响，而搭配开放羽片的翼羽，则会降低空气动力学效率。研究人员还在窃蛋龙类的尾羽龙(Caudipteryx)身上发现了结构简化的开放羽片翼羽，这一发现与其被推测的无飞行能力特征相符，但并非决定性证据。 综合来看，这些观测结果对于我们复原各类恐龙的外观，以及理解羽毛的功能与演化历程，均具有广泛的启示意义。