Archimyrmex

Archimyrmex is an extinct genus of ant in the formicid subfamily Myrmeciinae, described by palaeoentomologist Theodore Cockerell in 1923. The genus contains four described species, Archimyrmex rostratus, Archimyrmex piatnitzkyi, Archimyrmex smekali and Archimyrmex wedmannae. Archimyrmex is known from a group of Middle Eocene fossils which were found in North America, South America, and Europe. The genus was initially placed in the subfamily Ponerinae, but it was later placed in Myrmeciinae; it is now believed to be the ancestor of the extant primitive genus Myrmecia from Australia. Despite this, Archimyrmex is not a member to any tribe and is regarded as incertae sedis within Myrmeciinae. However, some authors believe Archimyrmex should be assigned as incertae sedis within Formicidae. These ants can be characterised by their large mandibles and body length, ranging from . They also have long, thin legs and an elongated mesosoma (thorax) and petiole.

== History and classification == When described the genus Archimyrmex was known from a solitary fossil preserved as an impression in fine shale of the Green River Formation in Colorado. The fossil was recovered in July 1922 from the "station 1" fossil site near the top of the Ute trail by entomologist Wilmatte Porter Cockerell. One side of the A. rostratus holotype is currently deposited in the University of Colorado paleontology collections while the counterpart is in the US National Museum, and an additional eleven fossils were known as of 2002. The holotype was first studied by palaeoentomologist Theodore Dru Alison Cockerell of the University of Colorado and his 1923 type description of the new genus and species was published in The Entomologist. The specific epithet "rostratus" is a reference to the beak-like outline of the mandibles seen in the type specimen.