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Atrypa
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Atrypa spinosa Illustration of an early Silurian coral-stromatoporoid community showing various labeled marine organisms, including corals, bryozoans, brachiopods, crinoids, trilobites, and a nautiloid, arranged on and around a block of seafloor substrate with a scale bar indicating centimeters. Silurian Pentamerus community
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Atrypa spinosa
Atrypa spinosa Atrypa spinosa, of Middle Devonian age, from Erie county, New York.

Atrypa

fossil brachiopod genus
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History

Atrypa, genus of extinct brachiopods, or lamp shells, that has a broad time range and occurs abundantly as fossils in marine rocks from the Silurian through the Early Carboniferous (444 million to 318 million years ago). Many species of Atrypa have been described. The genus is easily recognized by its distinctive concentric growth lines and peculiar outgrowths of the shell. It is unusual that in some Devonian exposures the abundant remains of only the pedicle (foot) valves of Atrypa occur; the brachial (upper) valves are rare or absent—apparently because of some sort of selective ocean current action.

This article was most recently revised and updated by Richard Pallardy.