Iniopterygiformes Temporal range: Carboniferous
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Iniopteryx rushlaui | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Subclass: | Holocephali |
Order: | †Iniopterygiformes Zangerl & Case, 1973 |
Families | |
Iniopterygiformes (Originally spelled Iniopterygia and sometimes informally abbreviated as "iniops")[1][2][3] is an extinct order of cartilaginous fish known only from the Carboniferous period of the United States. Iniopterygians are characterized by large, superficially wing-like pectoral fins positioned upwards behind the head, from which the name of the group (translated as "nape fin")[1] is derived. Iniopterygians are also noted to possess proportionally large skulls and eyes, armor plates composed of dentin, and "tooth-whorls" of fused teeth. Their elongated pectoral fins bore large, denticle-covered spines, and they are thought to have used them to swim using a "flying" motion.[1][4] The iniopterygians were comparatively small chondrichthyans, with the largest species reaching only 50 cm (20 in) in length.[1]
The group is regarded as a relative of modern chimaeras, and is placed in the subclass Holocephali. Two families of iniopterygians are recognized; the Sibyrhinchidae and the Iniopterygidae, with the latter containing only the genera Iniopteryx and Promyxele and the former housing all other named genera.[3][5] The classification of the iniopterygians, both with each other and with other groups of holocephalan, has been considered problematic.[5]