actinopterygii defined in 1951 yearactinopterygii - actinopterygii;
actinopterygii - A class of fish (or often regarded as a sub-class of the class Osteichthyes); includes all common fish except sharks and skates. Characterized by bony skeleton; absence of a central skeletal axis in paired fins, their skeletal support being like the ribs of a fan; no opening of nostrils into mouth; air-bladder. Ganoid scales in primitive species. Compare with: Chondrichthytes, Cross-opterygii and Dipnoi, the other three classes of living fish. Appear first in Devonian (350 to 400 million years ago); originally freshwater, but later colonized the sea.
near actinopterygii in Knolik
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