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Furcacauda
Genus of jawless fishes From Wikipedia, the free encyclopedia
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Furcacauda is a genus of thelodontid agnathan from the Lower Devonian of Canada, and is the type genus of the order Furcacaudiformes.[2] It contains two species, both of which hail from the MOTH locality in the Mackenzie Mountains of the Northwest Territories.[2]
Furcacaudiform thelodontids were deep water jawless vertebrates with symmetrical fork and lobed-finned tails and scales smaller than typical loganellid and nikoliviid thelodonti scales.[1] Furcacaudiform thelodonts are noted as having a laterally compressed body, large anterior eyes, slightly posterior, lateral, and vertical to a small mouth, and a condensed curved row of branchial openings (gills) directly posterior to the eyes.[2] Many but not all had laterally paired fins.[2] Wilson and Caldwell also note the presence of a caudal peduncle and a long caudal fin made of two large lobes, one dorsal and one ventral separated by 8 to 14 smaller intermediate lobes, giving the appearance of a striated half-moon shaped tail[1] resembling the tail of a heterostracan.[2] A large square cavity within the gut connecting a small intestine to an anal opening lead many to believe that it is this genus that exhibits the first vertebrate stomach.[1] According to Wilson and Caldwell, their discovery of sediment infillings of fossils of the Furcacauda heintze fossils gives credence to the evolutionary development of stomach before jaws.[1]
The scales of Furcacauda are robust and abrasion-resistant, similar to modern sharks which live among rough substrates such as rocky caves or reefs.[3][4]
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Gallery of species
Furcacauda heintzae
Furcacauda fredholmae
References
External links
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