Paterinida

(paleontology) A small extinct order of inarticulated brachiopods, characterized by a thin shell of calcium phosphate and convex valves.

A small extinct order of inarticulate brachiopods that ranges in age from Early Cambrian to Middle Ordovician. The shell is chitinophosphatic in composition, and its outline is circular or elliptical. The ventral (pedicle) valve is more convex than the dorsal (brachial) valve. The pedicle was absent or emerged between the valves. The muscle scars are unusual compared to other inarticulates, and form narrow triangular tracks radiating from the posterior extremity of each valve. Except for their shell composition and lack of articulation, the Paterinida resemble articulate brachiopods. Members were presumably epifaunal and sessile. See also Brachiopoda; Inarticulata.