Phylum: Mollusca
Class: Bivalvia
Order: Pholadomyoida Newell, 1965
Cincinnatian Families: Grammysiidae

Geologic Range
?Early Ordovician, Middle Ordovician – Recent

Common Paleoecology
Pholadomyoida is an extant order of facultatively mobile infaunal suspension feeders

Characteristics of the Order

  • Relatively short to elongate
  • Nestling to fossorial forms with ventrally fused mantle lobes
  • Equivalve to subequivalve; generally approximately isomyarian
  • Hinge margin characteristically thickened or enrolled, with lateral teeth absent
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Treatise on Invertebrate Paleontology, Part N, Mollusca 6 (2 of 3) (1969):

  • Ordinal characters same as those of subclass Anomalodesmata.
  • (Characters of subclass) Relatively short to elongate, nestling to fossorial forms with ventrally fused mantle lobes; equivalve to subequivalve; generally approximately isomyarian; hinge margin characteristically thickened or enrolled, edentulous, or with one amorphous tooth and corresponding socket in one or each valve, lateral teeth absent; ligament opisthodetic or absent, where present associated in many genera with separate resilium and lithodesma; many genera said to have nacreous endostracum; living forms eulamellibranchiate; a few, septibranchiate.

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