The Paranotal (or flying-squirrel) theory of insect wing origin was first proposed by Fritz Müller in 1875, stating that wings originated from lateral expansions (paranotal lobes) of the thoracic terga used for gliding, similar to flying squirrels.

• Müller: Fritz Müller (1875) proposed the paranotal/gliding theory of insect wing evolution.
• Averof and Cohen: Proposed the gill-co-option molecular homology theory (1997).
• Kukalova-Peck: Advocated the epicoxal/exite origin theory from leg appendages.
• Trueman: Researched insect wing venation mechanics.

In the Comstock-Needham insect wing venation scheme, longitudinal veins alternate fluting between convex (+) ridges and concave (-) furrows: Costa (C+), First Cubitus (Cu1+), and Anal veins (A+) are convex (+), whereas Second Cubitus (Cu2-) is strictly concave (-), NOT convex.

• First cubitus (Cu1) vein: Convex vein (+).
• Second cubitus (Cu2) vein: Concave vein (-), NOT a convex vein.
• Costa vein: Prominent convex marginal vein (+).
• Anal vein: Generally convex (+).