摘要：SummaryThe bizarre scansoriopterygid theropodsYiandAmbopteryxhad skin stretched between elongate fingers that form a potential membranous wing. This wing is thought to have been used in aerial locomotion, but this has never been tested. Using laser-stimulated fluorescence imaging, we re-evaluate their anatomy and perform aerodynamic calculations covering flight potential, other wing-based behaviors, and gliding capabilities. We find thatYiandAmbopteryxwere likely arboreal, highly unlikely to have any form of powered flight, and had significant deficiencies in flapping-based locomotion and limited gliding abilities. Our results show that Scansoriopterygidae are not models for the early evolution of bird flight, and their structurally distinct wings differed greatly from contemporaneous paravians, supporting multiple independent origins of flight. We propose that Scansoriopterygidae represents a unique but failed flight architecture of non-avialan theropods and that the evolutionary race to capture vertebrate aerial morphospace in the Middle to Late Jurassic was dynamic and complex.Graphical AbstractDisplay OmittedHighlights•Flight potential of “membrane-winged” scansoriopterygian dinosaurs tested•They had little ability to use flapping-based flight or locomotion•Reduced gliding abilities compared with modern and fossil gliding animals•Scansoriopterygians, a failed experiment in pre-bird theropod flightPaleontology; Biological Sciences; Evolutionary Biology; Paleobiology
