Capros medianus, a boarfish

Capros medianus Swidnicki, 1986

Oligocene

Menilith Shales

Bircza

Carpathians

Poland

This species belongs to a small order of marine ray-finned fishes, the Zeiformes. The order consists of about 40 species in six (or seven?) families, mostly deep-sea types: Zeidae (Dories), Parazenidae (Parazen), Zeniontidae, Oreosomatidae, Grammicolepidae, Cyttidae (?) and Caproidae (Boarfishes). Zeiformes are considered to be the sister taxon of a group making up the order Beryciformes and a huge conglomeration of spiny-rayed fishes known as the "percomorpha," including the Perciformes. They range in size from less than 5 cm to up to 90cm.

Zeiformes are characterized by usually thin and deep, compressed, and oblong to disk-shaped bodies with 5 -10 soft rays and possibly a spine in the pelvic fins, 5 -10 dorsal fin spines and up to 4 anal fin spines. The upper jaw with minute, slender conical teeth is more or less protrusible. With their greatly compressed head and body, large mouth, and extremely protrusible upper jaw, the Zeiformes are successful ambush predators. They slowly approach an unsuspecting small fish by means of undulating waves of the transparent soft dorsal and anal fins. In one quick motion they drop the "trapdoor" lower jaw, shoot out the upper jaw, and expand the gill cavity, sucking in the hapless prey along with a considerable volume of water. Zeiform fishes are carnivores; they feed mainly on a variety of fishes but also consume cephalopods and crustaceans.

This fish here is a Capros medianus from the menilith shales of Bircza in the Polish Carpathians. Capros medianus is a member of the family Caproidae (Boarfish, Capros = boar from the Greek kapros). All members of this order are characterized by a laterally compressed body that is as high as it is long. Boarfishes typically have three spines and five soft rays in the anal fin. The pectoral fins are rounded, the pelvic fins set below them (1 stout spine and 5 slightly softer finrays). The first dorsal fin consists of about nine to ten spikes, the second dorsal fin has 23 to 25 soft finrays. The large eye is well suited to its habitat in deep marine waters ranging from 40m to 600m. The protractile mouth, forming a small tube when protruded, is perfect for catching small copepods, mysids, benthic crustaceans and worms. The living species are all characterized by red coloration.

Swidnicki, J. 1986. Oligocene Zeiformes from the Polish Carpathians. - Acta Palaeontologica Polonica, Vol 31, No. 1-2, 111-135.