''Cyrtospirifer'' is an extinct genus of

brachiopod Brachiopods (), phylum (biology), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear e ...

s. The fossils are present in the Middle and Upper

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

Taxonomy

It is likely that '' Tenticospirifer'', that itself appeared during early

Givetian The Givetian is one of two faunal stages in the Middle Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Eifelian Stage and followed by the Frasnian Stage. It is named after the town of Givet in ...

, includes the ancestor of ''Cyrtospirifer''. ''Cyrtospirifer'' first occurs in western Europe in the Late Givetian. ''Tenticospirifer'' has a relatively narrow hinge line and an inflated and thick shell in common with two of the oldest species known, ''C. verneuiliformis'' and ''C. aperturatus''. This group dominated during the late Givetian, but was replaced by other species, such as ''C. syringothyriformis'' and ''C. verneuili'' which have wide hinge lines and thinner shells.

Description

''Cyrtospirifer'' has a medium to large sized shell, wider than long. File:Cyrtospirifer verneuili brachial valve.jpg, ''Cyrtospirifer verneuili'', 24mm long and about 60mm wide, brachial valve File:Cyrtospirifer verneuili pedunculate valve.jpg, pedicle valve File:Cyrtospirifer verneuili lateral.jpg, lateral File:Cyrtospirifer verneuili hinge.jpg, posterior File:Cyrtospirifer verneuili opening oblique.jpg, anterior

Reassigned species

* ''C. glaucus'' = '' Regelia glauca''

References

Prehistoric brachiopod genera Devonian brachiopods Fossils of Belgium Middle Devonian first appearances Famennian extinctions Spiriferida Paleozoic life of Alberta Paleozoic life of the Northwest Territories {{Brachiopod-stub