Phylum: Mollusca
Class: Tergomya
Order: Cyrtonellida (Horný, 1963)
Cincinnatian Families: Cyrtolitidae

Geologic Range
Cambrian – Devonian

Common Paleoecology
Cyrtonellida is an extinct order of slow-moving low-level epifaunal grazers

Characteristics of the Order

  • Monoplacophora
  • Incompletely to completely coiled, with apex at the anterior end
  • Reduced muscle scars, and the pairs are often specialized
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Jiří Frýda, (1999):

  • Cyrtonellida are monoplacophora with “shell incompletely or completely coiled, non-septate, the position of apex and spire presumed to be anterior; the number of paired scars reduced in connection with long shell, the single pairs often specialized.”

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