Monday, November 26, 2012

Sarcopterygi - flesh fin fish

Two lobe-fins from Devonian period and one from Triassic (up left)
Image Devonian times

Devonian bone fish include species with lobe-fins instead of bony fins. There are many different species classed together as Sarcopterygii (Gr. sarks and pteryx, flesh fin). In early models the fin is joined to the body with a single bone and the fins resemble more limbs than fins. These fish usually have two dorsal fins instead of the one other bone fish have.

Coelacanth Artist's view
Image Biology of Sharks and Rays
It was generally considered that the Devonian lobe-fins perished with the dinosaurs in the evening that ended the Mesozoic period. One of them was Coelacanth (Gr. koilos akantha, hollow backbone) found for the first time and named in 1839 by the famed Swiss paleontologist Louis Agassiz (1807-1873).

So it was quite a surprise when a live Coelacanth was caught by fishers in 1938 from Chalumne river in South Africa. Today it is known that such live fossils of Devonian fish are living near the coasts of Indian Ocean and Indonesia. Two subspecies have been identified, Latimeria chalumnae and Latimeria menadoensis.  

(see more in wikipedia )

Coelacanth caught in 1974 Comoros islands, Mozambique
Vienna Nature Museum, Austria

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