Cuneamya

Classification
Phylum: Mollusca
Class: Bivalvia
Order: Pholadomyoida
Family: Grammysiidae
Genus: Cuneamya Hall & Whitfield, 1875

Geologic Range
Middle Ordovician – Middle Devonian

Common Paleoecology
Cuneamya is an extinct genus of facultatively mobile infaunal suspension feeders

Identification in Hand Sample:

  • Subrhomboidal shell
  • Strongly incurved beaks
  • Posterior umbonal ridge rounded and broad
  • Uniform concentric ornamentation
  • No teeth or hinge plate

Geographic Occurrences

Species Differentiation

Published Description

Pojeta, Jr. & Runnegar (1985):

  • Ordovician pholadomyoids are not well known, but two genera Cuneamya and Rhytimya have the rugose comarginal and beaded radial ornament typical of the group; Rhytimya also gapes posteriorly.

Pojeta, Jr. (1971):

  • For various reasons, several Ordovician genera have been considered to be burrowing forms including: Cymatonota, Psiloconcha, Orthodesma, Rhytimya, and Cuneamya.
  • Also probably allied to this complex is the genus Cuneamya, a primarily Middle and Late Ordovician form which has a shell sculpture consisting of concentric undulations. As early as 1894, Ulrich related Cuneamya to Grammysia.

Treatise on Invertebrate Paleontology, Part N, Mollusca 6(2 of 3) (1969):

  • Subrhomboidal, tapering backward for maximum height at prominent, nearly terminal umbones and strongly incurved beaks to obliquely truncate posterior margin; lunule and escutcheon well developed; posterior umbonal ridge rounded and broad; lateral sulcus broad, faint, oblique; anterior surface with uniform concentric ornamentation; posterior slope smooth; without marginal gape.

Williams (1916):

  • Distinct from the gaping shells of the above types is a second strongly marked group separated from Grammysia by Hall and Whitfield in 1875 under the name Cuneamya. Cuneamya includes closed grammysoid shells without indications of radial sulcus, having the umbones tumid, terminal or nearly so, and directed strongly forward. The shells are transversely elongated or oblong. A lunule is present but not well-developed. The lingamental groove is well developed. There are no teeth or hinge plate, according to Ulrich. A large number of Upper Ordovician species are included in this genus. It may continue higher into the Silurian and possibly into the Lower Devonian or even higher.