Английская Википедия:Furcacauda

Материал из Онлайн справочника
Перейти к навигацииПерейти к поиску

Шаблон:Short description Шаблон:Automatic taxobox

Furcacauda is a genus of thelodontid agnathan from the Lower Devonian of Canada, and is the type genus of the order Furcacaudiformes.[1] Furcacaudiform thelodontids were deep water jawless vertebrates with symmetrical fork and lobed-finned tails and scales smaller than typical loganellid and nikoliviid thelodonti scales.[2] 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.[1] Many but not all had laterally paired fins.[1] 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[2] resembling the tail of a heterostracan.[1] 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.[2] 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.[2]

Gallery of species

Шаблон:Portal

References

Шаблон:Reflist

External links

Шаблон:Thelodonti Шаблон:Taxonbar

  1. 1,0 1,1 1,2 1,3 Шаблон:Cite journal
  2. 2,0 2,1 2,2 2,3 Ошибка цитирования Неверный тег <ref>; для сносок Wilson1993 не указан текст