The evolution of insect flight as documented in the fossil record
Palaeontology
Systematics and Morphology (Zoology)
Final Report Abstract
This project pursued several topics concerning the functional morphology, evolution, and phylogenetic relationships of winged insects (Pterygota), which comprise ca. two-thirds of all known species. A central objective was the evolution of the insect flight apparatus, which is unique among all flying animals. Most likely it is a highly important factor for the evolutionary success of the Pterygota. The seemingly substantial morphological differences between the three main groups of winged insects, Odonata (damselflies and dragonflies), Ephemeroptera (mayflies), and Neoptera (all remaining winged insects from stoneflies (Plecoptera) to the holometabolous insects) so far prevented the reconstruction of a ground pattern for the morphology of the flight apparatus of the last common ancestor of the Pterygota. Therefore, an important result of our investigations, utilizing high-resolution X-ray tomography, structured light scanning, photogrammetry, and classical light microscopy, is proposing homology hypotheses for the thoracic musculature and the wing base sclerites of all Pterygota. These homology hypotheses are based on our detailed analysis of the thoracic morphology and ontogenesis of Odonata and Ephemeroptera. This is an essential step to the reconstruction of the ground pattern of the flight apparatus of Pterygota. The data gathered from the fossil record of winged insects allowed for consolidating several Palaeozoic insect groups of hitherto uncertain phylogenetic affinities in the taxon Paoliida, which was found to be the extinct sister-group of Dictyoptera and therefore a key taxon for understanding pterygote evolution. The analysis of newly discovered and excellently preserved palaeodictyopterid nymphs showed that the alleged prothoracic winglets, which are known from several palaeodictyopterid taxa, were not wings and did not participate in the animal’s flight. Furthermore, the presence of abdominal spiracles documents a terrestrial way of life for this type of nymphs, which so far had been interpreted as aquatic. Our investigations of wing pad development in Carboniferous palaeodictyopteran insect nymphs corroborated the hypothesis of a dual model of insect wing origin, as deduced from developmental investigations in extant Pterygota. Insect wings obviously contain elements of the thoracic notal sclerites as well as pleural elements and basal elements of the extremities of the thoracic segments. Investigations of the oldest known representatives of winged insects also revealed that the diversity of e.g., the wing base morphology was distinctly higher at the beginning of the evolution of insect flight than it is in the extant fauna. Nevertheless, it was possible to identify the homologies in the wing base sclerites in Palaeozoic Palaeodictiyoptera and the extant representatives of the Ephemeroptera, Odonata, and Neoptera.
Publications
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(2014). Late Palaeozoic Paoliida is the sister group of Dictyoptera (Insecta: Neoptera). Journal of Systematic Palaeontology, 12(5), 601–622
Prokop, J., Krzeminski, W., Krzeminska, E., Hörnschemeyer, T., Ilger, J. M., Brauckmann, C., Grandcolas, P., Nel, A.
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(2016). New Carboniferous fossils of Spilapteridae enlighten postembryonic wing development in Palaeodictyoptera. Systematic Entomology, 41(1), 178–190
Prokop, J., Nel, A., Engel, M. S., Pecharová, M., & Hörnschemeyer, T.
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(2017). A remarkable insect from the Pennsylvanian of the Joggins Formation in Nova Scotia, Canada: insights into unusual venation of Brodiidae and nymphs of Megasecoptera. Journal of Systematic Palaeontology, Vol. 15, 2017 (12)
Prokop, J., Pecharová, M., Nel, A., Grey, M., & Hörnschemeyer, T.
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(2017). Paleozoic Nymphal Wing Pads Support Dual Model of Insect Wing Origins. Current Biology, 27(2), 263–269
Prokop, J., Pecharová, M., Nel, A., Hörnschemeyer, T., Krzemińska, E., Krzemiński, W., & Engel, M. S.
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(2018). The wing base of the palaeodictyopteran genus Dunbaria Tillyard: Where are we now? Arthropod Structure & Development, 47(4), 339–351
Prokop, J., Pecharová, M., Nel, A., & Hörnschemeyer, T.
