See text Archaeus (Greek for "ancient one") is an extinct genus of marine jackfish from the Paleogene of Europe, where it inhabited the former Tethys Ocean.

The oldest species, A. oblongus is from the early Ypresian epoch of Eocene Turkmenistan, and the last species, A. glarisianus and A. solus, are from the early to middle Rupelian, of the Matt Formation of Canton Glarus, Switzerland and the Pshekha Formation of North Caucasus, Russia.

[1][2] In life, Archaeus species would have resembled a small trevally, though, Archaeus had a proportionally smaller mouth, and larger eyes, and the tail was more fan-shaped, rather than crescent-shaped.

A specimen of A. glarisianus from the Oligocene of Abkhazia is now thought to represent an extinct species of Caranx, C.

[2] This article about a prehistoric ray-finned fish is a stub.