Palaeopteran

Palaeopteran is a superorder of insects that includes the extinct order Palaeodictyoptera and the extant order Ephemeroptera, which comprises the mayflies. The name "palaeopteran" refers to the characteristic feature of this group: their forewings and hindwings are not folded flat over the abdomen when at rest, unlike the neopteran insects. Instead, palaeopterans hold their wings erect, typically held together above their body or splayed out to the sides. This ancestral wing posture is a key distinction between palaeopterans and the vast majority of modern insects.

The fossil record for palaeopterans is extensive, with many diverse forms found in Carboniferous and Permian deposits. The Palaeodictyoptera, though entirely extinct, were a significant group of ancient insects. They were generally large, with complex wing venation, and occupied various ecological niches. Mayflies, the living representatives of the palaeopterans, are characterized by their delicate, membranous wings and aquatic larval stage, known as a nymph. Adult mayflies are short-lived, often emerging in large numbers in synchronized events. Their simplified mouthparts and lack of functional digestive systems in the adult stage reflect their primary purpose of reproduction. The evolutionary relationship between the extinct Palaeodictyoptera and the extant Ephemeroptera solidifies the palaeopteran superorder as a distinct lineage within the insect class.