| Furcacauda | |
|---|---|
 | |
| Furcacauda fredholmae | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Infraphylum: | Agnatha |
| Class: | † Thelodonti |
| Order: | † Furcacaudiformes |
| Family: | † Furcacaudidae |
| Genus: | † Furcacauda Wilson & Caldwell, 1998 |
| Type species | |
| Furcacauda heintzae | |
| Species | |
| |
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]
Contents
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]
