Sarcopterygii
Sarcopterygii
Sarcopterygii (pronounced: /ˌsɑːrkoʊptəˈrɪdʒiaɪ/), also known as lobe-finned fishes, are a clade of Osteichthyes, or bony fishes, characterized by their fleshy, lobed, paired fins, which are joined to the body by a single bone. The name 'Sarcopterygii' is derived from the Greek words 'sarx' meaning flesh and 'pteryx' meaning fin.
Characteristics
Sarcopterygii are distinguished from their sister group, the Actinopterygii, or ray-finned fishes, by the form of their fins. While Actinopterygii have fins supported by thin, bony rays, Sarcopterygii have fins that are lobe-like and fleshy, supported by a central core of bones.
Evolution and Fossil Record
The Sarcopterygii first appeared in the Silurian period, around 420 million years ago. They are of great evolutionary interest as they include the ancestors of all land-dwelling vertebrates, the Tetrapoda. The most famous Sarcopterygian is probably the Coelacanth, a genus of deep-sea fishes thought to have been extinct for 65 million years until a living specimen was discovered in 1938.
Classification
Sarcopterygii are divided into two extant subclasses: the Coelacanthimorpha, which includes the coelacanths, and the Dipnoi, or lungfishes. A third, extinct group, the Osteolepiformes, is thought to be the ancestor of all tetrapods.
See Also
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