English: Jumping bristletails.
Synonym: Microcoryphia; Trinemura; Protothysanura Crampton.
Clades: Palaeoptera; Insecta; Arthropoda; Animals.
Genera: 500 species; 2 families.
Archaeognata are some of the most evolutionarily primitive insects. They appeared in the Middle Devonian period at about the same time as the arachnids.
Until the late 20th century Zygentoma and Archaeognatha were combined in Thysanura as both possess three-pronged tails comprising two lateral cerci and a medial epiproct or appendix dorsalis.
In the late 20th century, it was recognized that the order Thysanura was paraphyletic, thus the two suborders were each raised to the status of an independent monophyletic order, with Archaeognatha sister taxon to the Dicondylia, including the Zygentoma.
The appendix dorsalis is considerably longer than the two cerci in Archaeognatha. In Zygentoma the three organs are subequal in length.