The Archaeognatha are an order of apterygotes, known by various common names such as jumping bristletails. Among extant insect taxa they are some of the most evolutionarily primitive; they appeared in the Middle Devonian period at about the same time as the arachnids.

bristletail, (order Archaeognatha), any of approximately 350 species of primitive wingless insects that measure from 5 to 20 mm (0.2 to 0.8 inch) in length when they are fully grown and have three slender bristlelike appendages at the tip of the abdomen.

Greek Origins of Name: Archeognatha, derived from the Greek “archeo” meaning ancient and “gnatha” meaning jaw, refers to the primitive (monocondylic) manner in which the mandibles connect with the head capsule. Apterygote (primitively wingless) Body cylindrical.

The Archaeognatha are an order of apterygotes, known by various common names such as jumping bristletails. Among extant insect taxa they are some of the most evolutionarily primitive; they appeared in the Middle Devonian period at about the same time as the arachnids.

Archaeognatha is an order of wingless insects, also known as jumping bristletails. They are among those insects which changed least during evolution. They first appear in the Devonian period along with the arachnids (Spiders). The name Archaeognatha is derived from Greek Archaeos meaning "ancient" and gnatha meaning "jaw".

Archaeognathans are medium-sized, elongate-cylindrical apterygotes, with some 500 species in two extant families. The head bears three ocelli and large compound eyes that are in contact medially.

Archaeognatha. The order Archaeognatha (sometimes called Microcoryphia) includes insects commonly known as jumping bristletails. The members of this order are distinctive because their mandibles connect with the head capsule in only one place (monocondylic).