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.