page_title: Insect wing
section_title: Fossils
hierarchical_section_title: Insect wing / Evolution / Fossils
caption_attribution_description: English: Holotype wing of the extinct Cimbrophlebia brooksi. Photographed after description. 49.5 Million Years old; "Boot Hill", Klondike Mountain Formation, Republic, Washington, USA. Stonerose Interpretive Center Collection # SR 06-20-05 A.
context_page_description: Insect wings are adult outgrowths of the insect exoskeleton that enable insects to fly. They are found on the second and third thoracic segments, and the two pairs are often referred to as the forewings and hindwings, respectively, though a few insects lack hindwings, even rudiments. The wings are strengthened by a number of longitudinal veins, which often have cross-connections that form closed "cells" in the membrane. The patterns resulting from the fusion and cross-connection of the wing veins are often diagnostic for different evolutionary lineages and can be used for identification to the family or even genus level in many orders of insects.
  Physically, some insects move their flight muscles directly, others indirectly. In insects with direct flight, the wing muscles directly attach to the wing base, so that a small downward movement of the wing base lifts the wing itself upward. Those insects with indirect flight have muscles that attach to and deform the thorax, causing the wings to move as well.
  The wings are present in only one sex in some groups such as velvet ants and Strepsiptera, or are selectively lost in "workers" of social insects such as ants and termites.
context_section_description: Fossils from the Devonian (400 million years ago) are all wingless, but by the Carboniferous (320 million years ago), more than 10 different genera of insects had fully functional wings. There is little preservation of transitional forms between the two periods. The earliest winged insects are from this time period (Pterygota), including the Blattoptera, Caloneurodea, primitive stem-group Ephemeropterans, Orthoptera and Palaeodictyopteroidea. Very early Blattopterans (during the Carboniferous) had a very large discoid pronotum and coriaceous forewings with a distinct CuP vein (an unbranched wing vein, lying near the claval fold and reaching the wing posterior margin). Even though the oldest definitive insect fossil is the Devonian Rhyniognatha hirsti, estimated at 396–407 million years old, it possessed dicondylic mandibles, a feature associated with winged insects.
  During the Permian, the dragonflies (Odonata) were the dominant aerial predator and probably dominated terrestrial insect predation as well. True Odonata appeared in the Permian and all are amphibious. Their prototypes are the oldest winged fossils, go back to the Devonian, and are different from other wings in every way. Their prototypes may have had the beginnings of many modern attributes even by late Carboniferous and it is possible that they even captured small vertebrates, for some species had a wing span of 71 cm. The earliest beetle-like species during the Permian had pointed, leather like forewings with cells and pits. Hemiptera, or true bugs had appeared in the form of Arctiniscytina and Paraknightia having forewings with unusual venation, possibly diverging from Blattoptera.
  A single large wing from a species of Diptera in the Triassic (10 mm instead of usual 2–6 mm) was found in Australia (Mt. Crosby).This family Tilliardipteridae, despite of the numerous 'tipuloid' features, should be included in Psychodomorpha sensu Hennig on account of loss of the convex distal 1A reaching wing margin and formation of the anal loop.
caption: Holotype wing of the extinct Cimbrophlebia brooksi. 49.5 Million Years old; "Boot Hill", Klondike Mountain Formation, Washington, USA.
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