| Mucrospirifer Temporal range: Devonian |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Brachiopoda |
| Class: | Rhynchonellata |
| Order: | Spiriferida |
| Family: | Mucrospiriferidae |
| Genus: | Mucrospirifer Grabau, 1931 |
| Species | |
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See text. |
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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. These 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.