|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Rhynchonellata - Orthida - Plaesiomyidae
|Year||Name and author|
|1928||Dinorthis quadriplicata Willard p. 271 figs. pl. 1, fig. 13; pl. 3, figs. 5, 6|
|1928||Dinorthis transversa Willard p. 271 figs. pl. 2, figs. I, 2, 6,|
|1942||Dinorthis transversa Butts p. 83 figs. pl. 85, figs. 14-16|
|1956||Dinorthis transversa Cooper pp. 398 - 400 figs. Plate 58B, figures 4-10; plate 58, C, figures 11-27; plate 268, J, figures 45-47|
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|G. A. Cooper 1956||Species variable, outline subrectangular, width greater than length, greatest width at about the middle. Cardinal extremities rounded, varying from nearly a right angle to obtuse. Lateral margins broadly rounded, generally sloping slightly toward the center ; front margin nearly straight : anterolateral extremities somewhat narrowly rounded. Anterior commissure broadly uniplicate. Surface multicostate ; median 4 to 6 costae generally stronger than the others and usually unbifurcated in young parts of the shell. Costae on the flanks usually bifurcated near their midlength, but on old or large specimens additional bifurcation takes place near the front margin creating 3 generations of costae. Some specimens show bifurcation of the larger median costae at the front.
Pedicle valve in anterior profile gently to moderately concave ; in lateral profile umbonal region more or less strongly convex, while the front two-thirds are moderately to strongly concave. Swollen umbonal region short; median strong costae often indistinctly define a poorly developed fold at least in the posterior half. Interarea short, nearly procline. Flanks varying from concave to flat or very gently convex.
Brachial valve moderately convex in lateral profile with the greatest convexity at about the middle ; anterior profile moderately to strongly rounded, often with a moderately strong median depression. Sulcus originating at the beak, moderately to strongly impressed and generally extending to the anterior margin where it usually is shallower than on parts posterior to the margin. Flanks bounding sulcus narrowly swollen. Posterolateral slopes generally steep. Interarea short, orthocline.
Pedicle valve with muscle area slightly wider than long, tapering slightly posteriorly. Adductor field large, nearly circular. A slight elevation separates anterior ends of diductor impressions. Median ridge of brachial valve not quite reaching center, cardinalia small.