Rhombotrypa subquadrata

Phylum: Bryozoa
Class: Stenolaemata
Order: Trepostomatida
Family: Amplexoporidae
Genus: Rhombotrypa
Species: Rhombotrypa subquadrata (Ulrich, 1882)

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History: (Under Monotrypella subquadrata, Nickles & Bassler, 1900)

  • 1882 Monotrypella subquadrata Ulrich, Jour. Cincinati Soc. Nat. Hist., V, p. 249, pl. xi, 4-4b.
  • 1894 Monotrypella quadrata var. subquadrata J.F. James, Jour. Cincinnati Soc. Nat. Hist., XVI, p. 199.
  • Cincinnati (Richmond0: Osgood, Indiana,; Blanchester, Hanover, and Oregonia, Ohio.

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Stratigraphic Occurrences


Geographic Occurrences

Map point data provided by iDigBio.
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Sequences (Formations)

  • C5 Sequence (Liberty, Waynesville)
  • C4 Sequence (Arnheim)

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Identification in Hand Sample

  • Zoarium Morphology: Ramose (large) to lobate; diameter: 2-3 mm
  • Zoecia: Square (or rhombic/quadrate); Thick-walled; 7-8 in 2mm; No Acanthopores
  • Mesozooids: Present
  • Monticules: Surface smooth
  • Maculae: Or larger apertures; slightly elevated.

Rhombotrypa subquadrata from Waynesville Formation of Franklin County, Indiana (OUIP 1621)

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McFarlan (1931):

  • This species can be distinguished from Rhombotrypa subquadrata by its larger form, (R. subquadrata’s branches are generally 2-3mm in diameter), and by the absence of mesopores (R. subquadrata has mesopores)

Davis (1998):

  • Unique in the rhombic or quadratic cross-section of the zooecia.

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