During its 320 million years evolution, dragon- and damselflies (Odonata) wing morphology underwent intense modifications. The resulting diversity prompted comparative analyses focusing on phylogeny. However, homoplasy proved to plague wing-related characters. Concurrently, limited benefits were obtained from considering fossil taxa, similarly impacted. Herein we investigate two aspects particularly affected by convergence, namely the acquisition of vein-like structuring elements derived from regular cross-venation, termed conamina; and the evolution of butter knife wing shape. Conamen implementation is found to be consistently linked with vein curvature sharpening, itself generating potential breaking points. Conamina therefore likely evolved to address wing integrity issues during ever-more-demanding flight performance. Moreover, an existing conamen is likely to trigger the acquisition of further, associated conamina. As for butter knife shape, previously documented in the extinct Archizygoptera and among damselflies, we report a new, 315-million-years-old occurrence with the rare species Haidilaozhen cuiae gen. et sp. nov. (family Haidilaozhenidae fam. nov.), from the Xiaheyan locality (China). The repeated acquisition of butter-knife-shaped wing can be related to slow-speed flight and, in turn, predator avoidance. In both cases of iterated regularities, the unique ‘network-and-membrane’ wing design proper to insects is found to compose a strong, constraining factor.

The dataset contains a RTI (Reflectance Transformation Imaging) of the right wings of the fossil insect specimen MNHN.F.R51142 ('Muséum National d'Histoire Naturelle', Paris, France), holotype of Meganeura monyi (Brongniart, 1884).

The RTI file composing this dataset was derived from a set of 54 photographs obtained using a light dome of about 50 cm in diameter and equipped with 54 LEDs. Both the light dome and camera (a Canon EOS 5DS equipped with a 50 mm macro lens, all Canon, Tokyo, Japan) were driven by a control box (dome and control box, Flydome, Paris, France). Obtained images were then batch-optimized using Adobe Photoshop CS6 and were further compiled into an RTI file using the RTI Builder software v. 2.0.2 using the HSH fitter (software freely available from Cultural Heritage Imaging, San Francisco, CA, USA).

The RTI file composing this dataset can be opened using RTIviewer (software freely available from Cultural Heritage Imaging, San Francisco, CA, USA).