Earliest evidence of 'feather-like' integumentary structures in a Middle Triassic stem-diapsid.

Amongst reptiles, complex, filamentous integumentary structures are present as feathers and pycnofibers in Ornithodira (birds, non-avian dinosaurs, and pterosaurs). Several exceptionally preserved and undescribed specimens of a non-ornithodiran stem-diapsid reptile from Grès à Voltzia (Anisian, Middle Triassic) of northeastern France exhibit remarkable integumentary structures, as well as a complete skull and postcranium. We propose to use propagation phase-contrast synchrotron microtomography (PPC-SRμCT) to investigate the anatomy of both its integumentary structures and skeleton. This will allow us to describe the new species, determine its evolutionary position in the reptile tree, and analyse the function of the integumentary structures to decide between two competing hypotheses: (a) an aerial gliding mechanism or (b) an elaborate display structure. This study will have wide-ranging implications for our understanding of filamentous body covering in reptiles.

在爬行动物类群中，复杂的丝状皮肤衍生物（filamentous integumentary structures）以羽毛（feathers）和羽纤丝（pycnofibers）的形式存在于鸟颈类主龙（Ornithodira）——该类群涵盖鸟类、非鸟类恐龙与翼龙——之中。产自法国东北部沃尔茨亚砂岩（Grès à Voltzia，中三叠世安尼阶（Anisian, Middle Triassic））的一件未正式描述的非鸟颈类主龙基干双孔类爬行动物（non-ornithodiran stem-diapsid reptile）标本保存状态极佳，其不仅展现出特征鲜明的皮肤衍生物结构，还附带完整的头骨与颅后骨骼。我们拟采用传播相位衬度同步辐射显微断层扫描（propagation phase-contrast synchrotron microtomography, PPC-SRμCT）技术，对该标本的皮肤衍生物与骨骼解剖结构开展研究。本研究将完成该新物种的形态描述，明确其在爬行动物系统发育树中的演化位置，并通过分析皮肤衍生物的功能，验证两种相互竞争的假说：（a）空中滑翔结构假说，或（b）精细展示结构假说。此项研究将为我们理解爬行动物的丝状身体覆盖物演化提供广泛的学术启示。