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The sarcopterygians appeared as early as the
Late Silurian along with other types of bony fish. They diversified
in the Devonian and were a more significant group than
the actinopterygians at that time. They were mostly large fish
that flourished in marine, brackish and fresh water. Most forms
became extinct in the Late Devonian extinction event and the only
marine forms that remained were the coelacanths.
Freshwater types were still abundant, including the rhizodonts
and lungfish. In the Mesozoic, the coelacanths became less common
in the seas, and in the freshwater environment only the lungfish
remained who virtually looked identical to modern species. Today
only seven species of the once diverse sarcopterygians remain.
Sarcopterygii
|---+----Onychodontiformes
| `---Actinistia
|--- Rhipidistia
|----Dipnomorpha
`----+----Rhizodontiformes
`----Osteolepiformes
|-----Elpistostegalia
`----TETRAPODA
Author: Snorri Sigurdsson (Email: ss4460@bristol.ac.uk)
Last updated: 14 November 2004
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