Phylum: Mollusca
Class: Gastropoda
Order: Euomphalina
Cincinnatian Families: Holopeidae, Platyceratidae

Geologic Range
Early Ordovician – Late Cretaceous

Common Paleoecology
Euomphalina is an extinct order of stationary, epifaunal suspension feeders

Characteristics of the Order

  • Mostly discoidal shell
  • Commonly contains channel presumed to be exhalant, which occupies an angulation on the outer part of the upper whorl surface
  • Most organisms widely phaneromphalous
  • Thick shell wall with calcite on outside and aragonite on inside
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Treatise on Invertebrate Paleontology, Part I, Mollusca 1 (1960): Under Superfamily Euomphalacea

  • Shell mostly discoidal; orthostrophic or hyperstrophic; commonly with channel presumed to be exhalant occupying angulation on outer part of upper whorl surface; mostly widely phaneromphalous; shell wall relatively thick, with external prismatic layer of calcite which may be pigmented and internal layer of aragonite which is lamellar but not nacreous

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