Furcacauda

Furcacauda
Temporal range: 419.2–393.3 Ma Lower Devonian[1]
Furcacauda fredholmae
Scientific classification Edit this 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]

  1. ^ 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.
  2. ^ 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.