| 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 spelledIniopterygia and sometimes informally abbreviated as "iniops")[1][2][3] is anextinctorder ofcartilaginous fish known only from theCarboniferous period of theUnited 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 ofdentin, 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 modernchimaeras, and is placed in the subclassHolocephali. Two families of iniopterygians are recognized; theSibyrhinchidae and theIniopterygidae, with the latter containing only the generaIniopteryx andPromyxele 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]
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