Banffia

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Banffia is a genus of animals described from Early Cambrian fossils. Its placement in higher taxa is controversial. The Banffia species were soft-bodied, and thus fossils are known primarily from the Burgess shales of Canada and the Chengjiang shales of China.

Banffia constricta is known from hundreds of fossils found in the Burgess shales. It is up to 10 cm in length, and divided equally into anterior and posterior parts. The entire body is twisted in a clockwise spiral, as seen from the front. This is believed to be a secondary adaptation from an initial bilateral condition. The anterior section is covered by two carapace-like un-mineralized shells that are fused together. A crown-like structure formed of three concentrate circular features surrounds the mouth. An antenna-form structure just posterior to the mouth may be a sensory organ. The posterior section is composed of 40 to 50 segments. The gut is straight, and the anus is at the terminal tip of the posterior section. The gut appears to have a series of diverticula or pouches. A possible circulatory system is visble in the fossils. Banffia constricta were probably filter or deposit feeders.

Banffia confusa is known from fossils from the Chengjiang shales. The animal also is divided, with segmentation visible in the posterior section. It is interpreted as a swimmer, and a filter feeder or detrivore.

[edit] Classification

There is no agreement on the classification of Banffia. Banffia constricta was assigned to the annelids by Walcott in 1911. As of 2006, different proposals would place Banffia in Urochordata, Vetulicolia or Arthropoda. While the body plan (equal anterior and posterior sections with segmentation) resembles that of the Vetulicolians, it is argued that the absence of gills and an endostyle, and the presence of gut diverticulae makes Banffia unlikely to be a member of the deuterostomes.