Dennis F. A. E. Voeten, Jorge Cubo, Emmanuel de Margerie, Martin RÃper, Vincent Beyrand, Stanislav BureÅ, Paul Tafforeau & Sophie Sanchez (2018)
Wing bone geometry reveals active flight in Archaeopteryx
Nature Communications 9, Article number: 923Â
doi:10.1038/s41467-018-03296-8
Archaeopteryx is an iconic fossil taxon with feathered wings from the Late Jurassic of Germany that occupies a crucial position for understanding the early evolution of avian flight. After over 150 years of study, its mosaic anatomy unifying characters of both non-flying dinosaurs and flying birds has remained challenging to interpret in a locomotory context. Here, we compare new data from three Archaeopteryx specimens obtained through phase-contrast synchrotron microtomography to a representative sample of archosaurs employing a diverse array of locomotory strategies. Our analyses reveal that the architecture of Archaeopteryxâs wing bones consistently exhibits a combination of cross-sectional geometric properties uniquely shared with volant birds, particularly those occasionally utilising short-distance flapping. We therefore interpret that Archaeopteryx actively employed wing flapping to take to the air through a more anterodorsally posteroventrally oriented flight stroke than used by modern birds. This unexpected outcome implies that avian powered flight must have originated before the latest Jurassic.