In most living insects (the Neoptera), there are three axillary sclerites that articulate with various
parts of the wing. In the Neoptera, a muscle on the third axillary causes it to pivot about the
posterior notal wing process and thereby to fold the wing over the back of the insect. (In some
groups of Neoptera, such as butterflies, the ability to fold the wings over the back has been
lost.) Two orders of winged insects, the Ephemeroptera and Odonata, have not evolved this
wing-flexing mechanism, and their axillary sclerites are arranged in a pattern different from that
of the Neoptera; these two orders (together with a number of extinct orders)
form the Paleoptera
Dostları ilə paylaş: