The evolution of insect flight as documented in the fossil record

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The appearance of wings is one the most spectacular novelties in insect evolution that took place already hundreds millions of years ago. The oldest unequivocal fossils of winged insects (Pterygota) are ca. 320 million years old. Other, ca. 400 million year old, fragmentary fossils indicate that already at that time pterygote species existed. Despite of, or perhaps because of, this very long evolutionary history, it is still not clear how and when exactly the flight apparatus of insects originated. Even extensive investigations in the extant Pterygota could not, so far, answer basic questions on the sequence of events, especially during the early time of the evolution of insect flight. For example, it is not clear from which parts of the insect body the wings originated and the phylogenetic relationships among the subgroups of Pterygota are still largely unresolved. This is true for the extant pterygotes like Ephemeroptera, Odonata and Neoptera including their fossil members, but also and especially for the extinct Palaeozoic Palaeodictyoptera, Diaphanopterodea, Permothemistida and Megasecoptera.To gain a better understanding of the processes during the evolution of the flight apparatus of the insects as well as of the evolution of insects in general, we will study Palaeozoic fossils from all higher taxa of Pterygota that show important parts of the flight apparatus beyond the venation of the wings, like the often complex wing joint and the thorax. We will investigate specimens from several Carboniferous and Permian fossil sites like, e.g., Hagen-Vorhalle (Germany), Commentry (France), Mazon Creek (USA), Sosnowiec (Poland), Tshekarda (Russia) with microscopy as well as with high resolution X-ray tomography, 3D-surface scanning (photogrammerty) and scanning electron microscopy. The comparative analysis of the acquired data, together with information on extant pterygotes, will allow for the reconstruction of the ancestral states of the flight apparatus of Pterygota as well as its subgroups. This will substantially extend our knowledge and understanding of the evolution of the insects, the group that by far comprises the largest number of species among all organisms.