RUTITRIGONIIDAE VAN HOEPEN, 1929

Halligan, William Keith, 2023, Washington State (USA) trigoniids (Bivalvia) from the conglomerate of Patterson Lake (Early Cretaceous), PaleoBios 40 (8), pp. 1-15 : 9

RUTITRIGONIIDAE VAN HOEPEN, 1929 RUTITRIGONIINAE VAN HOEPEN, 1929 RUTITRIGONIINI VAN HOEPEN, 1929

Diagnosis— Small to large, pyriform to ovate and subtrapezoidal, strongly inequilateral to subequilateral, moderately inflated to inflated, with weakly- to strongly-convex anterior margin, obliquely truncate to subrounded respiratory margin, anteriorly-positioned umbones and moderately-incurved opisthogyrous beaks; shallow sunken escutcheon unornamented, or with costellae continuous from area in early growth; escutcheon and areal rims sometimes nodate in early growth; weakly-bipartite area with oblique costellae in early to middle growth continuous from flank, mostly evanescing later;flank costellae mostly non-tuberculate, commarginal in early growth, subcommarginal to subhorizontal and oblique later, cutting across growth striae both anteriorly and posteriorly; flank costellae may become deflexed, wavy and discontinuous anteriorly, sometimes nodate, and effaced at varying distances from the posterior.

Late Kimmeridgian – Late Maastrichtian. ( Cooper 2015b)