|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Rhynchonellata - Rhynchonellida - Orthorhynchulidae
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.
|A. Williams 1962||Exterior - Elongately oval, strongly biconvex shells with a high dorsal fold and a deep ventral sulcus, truncated anteriorly so that the antero-median part of the pedicle valve projects dorsally like a tongue; radial ornamentation costate, with costae well defined posteriorly but tending to die out towards the margins of adult shells; hinge-line long and straight; ventral interarea well developed, strongly curved, anacline, delthyrium open with only flange-like traces of deltidial plates; dorsal interarea weak, anacline; shell substance impunctate.
Interior ofpedicle valve.--Teeth small, supported by long, slightly divergent dental lamellae, pedicle chamber well defined; muscle-field subrectangular, extending well beyond the dental lamellae although low extensions from them act as lateral boundaries, median lanceolate zone contained by a pair of faint ridges and presumably representing the adductor scar, anterior ends of diductor scars contained by a pair of narrow raised zones extending to the anterior margin along the sides of the sulcus and possibly representing the vascula media.
lnterior of brachial valve.--Crural bases subtriangular, flaring, concave ventrally and supported by a pair of plates convergent onto the median part of the valve floor to form a sessile cruralium; sockets small, delineated as concave areas lying lateral to the crural bases; muscle-field unknown.