Modiomorphidae

Classification
Phylum: Mollusca
Class: Bivalvia
Order: Modiomorphida
Family: Modiomorphidae (Miller, 1877)
Cincinnatian Genera: Corallidomus, Cymatonota, Modiolodon, Modiolopsis, Orthodesma, Whiteavesia

Geologic Range
Lower Ordovician – Lower Permian, ?Upper Permian

Common Paleoecology
Modiomorphidae is an extinct family of stationary epifaunal suspension feeders.

Description of the Family

  • Shell subovate, with or without radial ornamentation
  • Anterior lobe ahead of umbones and commonly with umbonal ridge or carina extending obliquely backward from umbones to posteroventral region
  • Anterior adductor generally small, deeply impressed , in many shells reinforced by bordering buttress
  • Posterior adductor relatively large, ovoid
  • Cardinal and posterior laterals may or may not be present.
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Treatise on Invertebrate Paleontology, Part N, Vol. 1 of 3 (1969):

  • Shell subovate with or without radial ornamentation, opisthodetic, without extended posterior wing, more or less modioloid in form, commonly , but not invariably expanded posteriorly, with anterior lobe ahead of umbones and commonly with umbonal ridge or carina extending obliquely backward from umbones to posteroventral region; anterior adductor generally small, deeply impressed , in many shells reinforced by bordering buttress; posterior adductor relatively large, ovoid; anterior laterals absent, cardinals and posterior laterals may or may not be present. It has been claimed but not satisfactorily demonstrated that some of these forms are edentulous. Some resemble Mytilacea and may represent ancestors of that group.

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Corallidomus


Cymatonota


Modiolodon


Modiolopsis


Orthodesma


Whiteavesia