Dielasma hastata (J. de C.Sowerby)
Lower Carboniferous, Carboniferous Limestone, Visean
Drumman More, Co. Armagh
largest 16 mm across
Dielasma is the earliest of the terebratulid brachiopods, an abundant and diverse group which, along with the rhynchonellids, became the dominant brachiopods through the Mesozoic and up to the present day. Dielasma is a fairly typical terebratulid, with a small, smooth, sack-shaped shell. It is not unlike the Lower Jurassic Waldheimia, a typical terebratulid from rocks more than 140 million years younger.
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