Furcacauda

Furcacauda; Temporal range: 419.2–393.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N Lower Devonian
	Furcacauda fredholmae
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Infraphylum:	Agnatha
Class:	†Thelodonti
Order:	†Furcacaudiformes
Family:	†Furcacaudidae
Genus:	†Furcacauda; Wilson & Caldwell, 1998
Type species
	Furcacauda heintzae;
Species
	Furcacauda heintzae; Furcacauda fredholmae;

Furcacauda is a genus of thelodontid agnathan from the Lower Devonian of Canada, and is the type genus of the order Furcacaudiformes.^[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, based on sediment infillings of fossils of the Furcacauda heintze, gives credence to the evolutionary development of stomach before jaws.^[1]

Gallery of species

Furcacauda heintzae
Furcacauda fredholmae

References

^ ^a ^b ^c ^d ^e Mark V. H. Wilson; Michael W. Caldwell (1993). "New Silurian and Devonian fork-tailed 'thelodonts' are jawless vertebrates with stomachs and deep bodies". Nature. 361 (6411): 442–444. doi:10.1038/361442a0.
^ ^a ^b ^c ^d Wilson, Mark V. H.; Caldwell, Michael W. (1998). "The Furcacaudiformes: A New Order of Jawless Vertebrates With Thelodont Scales, Based On Articulated Silurian and Devonian Fossils From Northern Canada". Journal of Vertebrate Paleontology. 18 (1): 10–29. doi:10.1080/02724634.1998.10011031. Archived from the original on 2010-06-18.

External links

Media related to Furcacauda at Wikimedia Commons
The Taxonomicon. (2004–2009) Retrieved November 6, 2009.

[Wilson1993-1] Mark V. H. Wilson; Michael W. Caldwell (1993). "New Silurian and Devonian fork-tailed 'thelodonts' are jawless vertebrates with stomachs and deep bodies". Nature. 361 (6411): 442–444. doi:10.1038/361442a0.

[Wilson1998-2] Wilson, Mark V. H.; Caldwell, Michael W. (1998). "The Furcacaudiformes: A New Order of Jawless Vertebrates With Thelodont Scales, Based On Articulated Silurian and Devonian Fossils From Northern Canada". Journal of Vertebrate Paleontology. 18 (1): 10–29. doi:10.1080/02724634.1998.10011031. Archived from the original on 2010-06-18.

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[2]