Phylum: Mollusca
Class: Cephalopoda
Order: Orthocerida
Family: Orthoceratidae
Genus: Pleurorthoceras Flower, 1962
Cincinnatian Species: Pleurorthoceras clarksvillense

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Geologic Range
Late Ordovician

Common Paleoecology
Pleurorthoceras is an extinct genus of nektonic carnivores

Identification in Hand Sample:

  • Slender, gradually expanding
  • Siphuncle orthochoanitic
  • Circular in cross section
  • Mural cameral deposits well developed
  • Transverse sutures

Geographic Occurrences

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Kroeger (2013):

  • Slender, gradually expanding, smooth orthocones; circular in cross section with straight, transverse sutures; chamber distance between one-third to one-half of the corresponding conch diameter, siphuncle subcentral to central; siphuncular segments subtubular, slightly expanded within chambers; septal necks short, suborthochoanitic; endosiphuncular deposits unknown; mural cameral deposits well developed. (Adopted from Flower 1962)

Pojeta (1995):

  • Medium-sized, slender, gradually expanding orthoconic longicones; circular in section with straight, transverse sutures. Cameral lengths from one-third to nearly one-half the diameter of the shell, with strongly curved, widely spaced septa. Body chamber long and tubular. Shell exterior smooth. Siphuncle slightly ventral of center, narrow in diameter, the subtubular segments only slightly expanded within camerae, twice as long as wide. Septal necks short, suborthochoanitic. Endosiphuncular deposits unknown. Cameral deposits well developed, initially mural, becoming mural-episeptal with ontogeny and deposits thickening ventrally to form a midventral boss.

Treatise on Invertebrate Paleontology, Part K (1964):

  • Like Michelinoceras externally, but siphuncle orthochoanitic, with somewhat inflated segments. Cameral deposits entirely mural.

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P. clarksvillense