Data from: The plumage and colouration of an enantiornithine bird from the Early Cretaceous of China

Brilliant colour displays and diverse feather morphologies that are often sexual ornaments are common throughout much of extant Avialae. Here we describe a new basal enantiornithine bird specimen recovered from the Early Cretaceous Jiufotang Formation of Liaoning Province in northeastern China. We present new information on the plumage of Bohaiornithidae as well as the first detailed colour reconstruction of an enantiornithine bird. The new specimen retains subadult skeletal characteristics, including periosteal pitting of the long bone epiphyses and unfused elements, while also preserving plumage evidence consistent with sexual maturity at the time of death. Exceptionally-preserved feathers cover the body, including elongate crown feathers, body contour feathers, asymmetrically-veined wing primaries, an alula and two elongate rachis-dominated rectrices that may have been sexual ornaments. The crown, neck, and body contour feathers retain elongate melanosome morphologies associated with weakly iridescent colouration in extant feathers. We provide additional evidence of preserved melanin using Raman spectroscopy; a rapid, non-destructive chemical technique. The new specimen provides data on skeletal ontogeny in the Bohaiornithidae as well as evidence for intraspecific communication functions of plumage.

现生鸟翼类（Avialae）类群中，色彩绚烂的羽饰与多样的羽毛形态（常作为性征装饰物）极为普遍。本文记述一件采自中国东北辽宁省早白垩世九佛堂组的全新基干反鸟（Enantiornithes）标本。本研究不仅补充了渤海鸟科（Bohaiornithidae）的羽毛相关新信息，还首次实现了反鸟类详尽的色彩重建。该新标本保留有亚成体骨骼特征，包括长骨骨骺的骨膜凹陷与未愈合的骨骼结构，同时留存的羽毛证据表明其死亡时已接近性成熟。其体表被保存极为精美的羽毛覆盖，涵盖额部长羽、体被廓羽、具不对称叶脉的初级飞羽、小翼羽，以及两枚可能作为性征装饰物的、以羽轴为主的修长尾羽。该标本的头部、颈部与体部廓羽中仍留存有与现生鸟类羽毛中弱虹彩色彩相关的细长型黑素体。我们通过拉曼光谱法（Raman spectroscopy）——一种快速且非破坏性的化学分析技术——进一步证实了标本中黑色素的保存。该新标本既为渤海鸟科的骨骼个体发育研究提供了新数据，也为羽毛的种内交流功能提供了实证依据。