The figure below shows the distribution of samples containing the orthid brachiopod Dinorthis.

[ Dinorthis distribution ]

Dinorthis is a common brachiopod in some parts of the MRV strata.

[ Dinorthis ]

Plaesiomys (Dinorthis) Hall & Clarke, 1892 [*Orthis pectinella Conrad & Emmons, 1842] [=Dinorthis Kobayashi, 1937]
Resembling P. (Plaesiomys), but radial ornamentation costate, exceptionally with incipient costellae.
M. Ord. Northern Hemisphere
Family Plaesiomyidae Schuchert, 1913.
Ventral interareas variably disposed, hinge lines wide; delthyrium and notothyrium rarely covered by deltidium and chilidium; ventral muscle field subquadrate, extending well beyond umbonal region; mantle canal system saccate, with proximal parts of vascula media short, divergent.
Order Orthida Schuchert & Cooper, 1932.

Treatise on Invertebrate Paleontology, H319.