Mucrospirifer

Mucrospirifer is a genus of extinct brachiopod in the class Rhynchonellata (Articulata) and the order Spiriferida. They are sometimes known as "butterfly shells". Like other brachiopods, they were filter feeders. Fossils occur mainly in middle Devonian strata.

The biconvex shell was typically 2.5 cm, but they could grow to 4 cm long. It has a fold, sulcus and costae. It was greatly elongated along the hinge line, which extends outward to form sharp points. This gave them a fin- or wing-like appearance. The apex area (umbo) of the pedicle valve contains a small fold for the pedicle. They lived in muddy marine sediments, and were attached to the sea floor via the pedicle.They sometimes look like two seashells stuck together.

Select species

 * Mucrospirifer albanensis
 * Mucrospirifer arkonensis
 * Mucrospirifer bouchardi
 * Mucrospirifer grabaui
 * Mucrospirifer medfordsis
 * Mucrospirifer mucronatus
 * Mucrospirifer paradoxiformis
 * Mucrospirifer profundus
 * Mucrospirifer prolificus
 * Mucrospirifer refugiensis
 * Mucrospirifer thedfordensis
 * Mucrospirifer williamsi