Cyrtospirifer

Cyrtospirifer is an extinct genus of brachiopods. The fossils are present in the Middle and Upper Devonian.
Taxonomy.
It is likely that "Tenticospirifer", that itself appeared during early Givetian, includes the ancestor of "Cyrtospirifer". "Cyrtospirifer" first occurs in western Europe in the Late Givetian. "Tenticospirifer" has a relatively narrow hingeline 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 hingelines and thinner shells.
Description.
"Cyrtospirifer" has a medium to large sized shell, wider than long.