Brachiopods- Mississippian Period -Composita subquadrata.JPG
Brachiopods - Composita subquadrata
Chesterian Zone of the Bangor Limestone Formation in northern Alabama
Mississippian Period (ca 325,000,000 yrs old)
Composita is a brachiopod genus that lived from the Late Devonian to the Late Permian. Composita had a smooth shell with a more or less distinct fold and sulcus and a round opening for the pedicle on the pedicle valve. Composita is included in the family Athyrididae (Order Athyridida) and placed in the subfamily Spirigerellinae. The Rhynchonellata is a class of Lower Cambrian to Recent articulate brachiopods that combines orders from within the Rhynchonelliformea (Articulata revised) with well developed pedicle attachment. Shell forms vary from those with wide hinge lines to beaked forms with virtually no hinge line and from generally smooth to strongly plicate. Most all are biconvex. Lophophores vary and include both looped and spiraled forms. Although morphologically distinct, included orders follow a consistent phylogenetic sequence.