Bony Fishes

Bony fishes or osteichthyans comprise two main monophyletic groups: the actinopterygians (rayfins, including the staples of the fish market and aquarium) and sarcopterygians (lobefins, fringefins or tasselfins, including lungfishes, coelacanths, and, perhaps unexpectedly or inconveniently, all land vertebrates or tetrapods). In the broadest terms, the two groups have similar histories, each with beginnings in the late Silurian or earliest Devonian, each with a primary radiation in the late Devonian and Mississippian, a secondary radiation in the Mesozoic, and a major Tertiary radiation, and each with an extant diversity of roughly 25,000 species (Nelson, 1994, p. 2). The remainder of this course (eight topics) is devoted to sarcopterygians, so I shall give almost all my space to the other half of bony fish diversity, the actinopterygians.