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The common denominator among most deposits of fossil insects and terrestrial plants is the lake environment. Those insects that became preserved were either living in the fossil lake (autochthonous) or carried into it from surrounding habitats by winds, stream currents, or their own flight (allochthonous).
A number of apterous insects have secondarily lost their wings through evolution, while other more basal insects like silverfish never evolved wings. In some eusocial insects like ants and termites , only the alate reproductive castes develop wings during the mating season before shedding their wings after mating, while the members of other ...
There are two basic aerodynamic models of insect flight. Most insects use a method that creates a spiralling leading edge vortex. [19] [20] Some very small insects use the fling-and-clap or Weis-Fogh mechanism in which the wings clap together above the insect's body and then fling apart. As they fling open, the air gets sucked in and creates a ...
For example, just by position one can identify species, albeit to a much lesser extent. Though most insects fold their wings when at rest, dragonflies and some damselflies rest with their wings spread out horizontally, while groups such as the caddisflies, stoneflies, alderflies, and lacewings hold their wings sloped roof-like over their backs ...
Prior to their existence on birds, feathers were present on the bodies of many dinosaur species. Through natural selection, feathers became more common among the animals as their wings developed over the course of tens of millions of years. [6] The smooth surface of feathers on a bird's body helps to reduce friction while in flight.
There is a similarity between their fore- and hindwings, and an additional pair of winglets on the prothorax, in front of the first pair of wings. They are known as " six-winged insects " because of the presence of a pair of wings on each of the thoracic segments.
Most birds experience an annual molt, typically after the breeding season, Shultz said, but species like American goldfinches replace their feathers twice a year.
The wings are moved by the rapid muscular contraction and expansion of the thorax. [11] The wings arise from the meso- and meta-thoracic segments and are similar in size in the basal groups. In more derived groups, the meso-thoracic wings are larger with more powerful musculature at their bases and more rigid vein structures on the costal edge. [7]