The figure below shows the distribution of samples containing the inarticulate brachiopod Lingula.

[ Lingula distribution ]

Lingula is a common inarticulate brachiopod in the MRV strata.

[ Lingula ]

Lingula Bruguiere, 1797 [*L. anatina Lamarck, 1801] [=Pharetra Boulton, 1798; Ligula Cuvier 1798; Ligularius Dumeriel, 1806; Lingularius Schuchert & LeVene, 1929]

Elongate, lateral margins gently convex to subparallel, ornament only of concentric growth lines; shell thin, slightly thickened in areas of muscle attachment. Internally without septa, low median ridge in brachial valve may be present extending from central scars to anterior lateral scars.
?Ord., Sil. - Rec., cosmopolitan
Family Lingulidae Menke, 1828
Elongate oval to spatulate in outline, more rarely subtriangular, gently biconvex; beak of pedicle valve with broadly triangular ventral depression or groove for passage of pedicle, posterolateral margins of valve thickened, striated, lacking flexure lines, but rarely forming well-defined triangular propareas. Beak of brachial valve with small, uninterrupted pseudointerarea, not extending as a plate into the valve. Principal musculature consisting of umbonal muscle, paired centrals, transmedians, anterior, outside and middle laterals. One pair of principal mantle canals (vascula lateralia) in each valve. Recent species with long, flexible pedicle, lophophore spirolophous, apices of spires medianly directed.
?Ord., Sil. - Rec.
Order Lingulida Waagen, 1885

Treatise on Invertebrate Paleontology, H263.