Holoptychius (from Greek: όλοςholos, 'whole' and Greek: πτυχήptyche 'fold') is an extinctgenus of marine & freshwater porolepiformlobe-finned fish from the Late Devonian period. It is known from fossils worldwide, from North America, South America, and much of Europe. The genus was first described by Louis Agassiz in 1839.
Description
Holoptychius was a streamlined predator about 50 centimetres (20in) long (though largest specimen could grow up to 2.5 metres (8.2ft)), which fed on other bony fish. Its rounded scales and body form indicate that it could have swum quickly through the water to catch prey. Similar to other rhipidistians, it had fang-like teeth on its palate in addition to smaller teeth on the jaws. Its asymmetrical tail sported a caudal fin on its lower end. To compensate for the downward push caused by this fin placement, the pectoral fins of Holoptychius were placed high on the body.
It was likely an ambush predator with a similar lifestyle to the modern arapaima. It had a distinct layer of hard but flexible scales that may have helped to fend off attacks from other predatory lobe-finned fish.
Species
A number of Holoptychius species have been described, the majority being dubious species known only from isolated scales. Only the following valid species are known by diagnostic remains:
In past sources, H. jarviki was frequently referred to as H. quebecensis, due to its material being conflated with that of Quebecius quebecensis, necessitating its description as a distinct species in 1996. The genus Glytolepis was also previously treated as a subgenus of Holoptychius.
The following dubious and undescribed species are known:
↑Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p.43. ISBN1-84028-152-9.
12Schultze, H. P.; Cloutier, R. (1996). "Porolepiform fishes (Sarcopterygii)"(PDF). Devonian fishes and plants of Miguasha, Quebec. Canada. Dr F. Pfeil, München.
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