The term has also been applied to the upper and lower calypters collectively. In flies (" Diptera"), the alula is a lobe of the posterior margin of the wing bounded proximally by the upper calypter, distally by the axillary incision, and anteriorly by the base of the anal vein. Since these species are not closely related to modern birds, either the alula evolved twice, or it did so more than 130 mya. The presence of an alula has been confirmed in several now- extinct ancient relatives of modern birds, including " Eoalulavis hoyasi" (an enantiornithine from the mid- Cretaceous, 115 mya) and the earlier " Protopteryx fengningensis". During stretching of the wing down toward the ground, the alula is abducted from the wing and can be clearly viewed. This functions in the same way as the slats on the wing of an aircraft, allowing the wing to achieve a higher than normal angle of attack – and thus lift – without resulting in a stall. When flying at a slow speeds or landing, the bird moves its alula slightly upwards and forward, which creates a small slot on the wing's leading edge. In most situations, the alula is held flush against the wing however, it can be manipulated. Like the larger flight feathers found on the wing's trailing edge, these alula feathers are asymmetrical, with the shaft running closer to anterior edge. The alula is the freely moving first digit, a bird's "thumb," and is typically covered with three to five small feathers, with the exact number depending on the species. The alula, or bastard wing, is a small projection on the anterior edge of the wing of modern (and some ancient) birds. For the Finnish ornithological journal of the same name, see Alula (journal) for the Hawaiian plant, see Brighamia insignis." :"This article is about the Alula feather.