Paranotal Hypothesis
This hypothesis proposes that wings are derivates of the paranotal lobes which first formed on the thoracic terga (Gullan & Cranston 2010).The lobes were used first for thermoregulation, then airfoils and then flapping wings (Klowden 2007). The lobes were selected for as they were believed to assist in gliding or other possible modes of flying (Klowden 2007). Secondary wing articulation and musculature also evolved with the formation of the wings (Klowden 2007).
Morphology of Elmidae or Riffle Beetles and the common position of the thoracic terga for all insects.Image provided by Segura et al. (2011)