| Iniopterygiformes Temporal range: Carboniferous | |
|---|---|
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| Life restoration of Iniopteryx | |
Scientific classification  | |
| 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]
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The group is regarded as a relative of modern chimaeras, and is placed in the subclass Holocephali. Two families of iniopterygians are recognized; the Sibyrhynchidae and the Iniopterygidae, with the former containing the genera Sibyrhynchus , Iniopera , and Inioxyele and the latter 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]
