Dicondylia

Dicondylia is a taxonomic group (taxon) that includes all insects except the jumping bristletails (Archaeognatha). Dicondylia species have a mandible attached with two hinges to the head capsule (dicondyl), in contrast to a hypothetical ancestral mandible with a single ball joint (monocondyl); the members of Archaeognatha do in fact have dicondylic mandibles, though they are not identical to the structure seen in "true" dicondylic insects.

== Dicondyle mandible and other features == The taxon is distinguished by the possession of a modified mandible with an additional joint canal, which also changes the muscle attachments of the mouth tools and allows a modified mandible movement compared to other mandibles (crustaceans, centipedes). This so-called dicondyle mandible has two joints with which it is attached to the head capsule, while non-insect taxa have only one single ball joint. The archaeognathans were once thought to have only a single articulation, but it has since been shown that they do possess two articulations that are homologous to those in other insects, though slightly different.