Phylum: Bryozoa
Class: Stenolaemata
Order: Trepostomatida
Family: Unassigned
Genus: Spatiopora Ulrich, 1882

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Type species: Spatiopora aspera (Ulrich, 1883)

Taxonomic History (Nickles & Bassler, 1900)

  • 1882 Spatiopora Ulrich, Jour. Cincinnati Soc. Nat. Hist., V, p. 155; ibid, VI, 1883, p. 166.
  • 1883 Spatiopora Foord, Contr. Micro-Pal. Cambro-Sil., p. 20.
  • 1889 Spatiopora Miller, North American Geol. Pal., p. 323.
  • 1890 Spatiopora Ulrich, Geol. Surv. Illinois, VIII, p. 381.
  • 1893 Spatiopora Ulrich, Geol. Minnesota, III, p. 319.
  • 1896 Spatiopora Ulrich, Zittel’s Textb. Pal. (Engl. ed.), p. 269.

Species in Cincinnatian of Ohio, Indiana, Kentucky (

  • Spatiopora aspera (Ulrich, 1883)
  • Spatiopora corticans (Nicholson, 1874)
  • Spatiopora lineata (Ulrich, 1883)
  • Spatiopora maculosa (Ulrich, 1883)
  • Spatiopora montifera (Ulrich, 1883)
  • Spatiopora tuberculata (Milne, Edwards and Haime, 1851)

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Geologic Range
Ordovician – Silurian

Stratigraphic Occurrences

Geographic Occurrences

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Sequences (Formations)

  • C5 Sequence (Waynesville)
  • C3 Sequence (Corryville)
  • C2 Sequence (Bellevue)
  • C1 Sequence (Clays Ferry/Kope: Economy/Fulton)

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Identification in Hand Sample:

  • Zoarium Morphology: Encrusting (often on Orthoceras)
  • Zoecia: Short and direct with irregular apertures; blunt spines at angles
  • Mesozooids:
  • Monticules: Elevated and elongate (usually conspicuous)
  • Maculae:

Note: Superficially similar to Atactopora, which also encrusts on cephalopods and has prominent elongate monticules.


Spatiopora sp. from McMillan formation of Brown County, Ohio (OUIP 667)

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Bassler (1911):

  • The single species of this genus noted in the Russian strata is so like an American form that it has not been differentiated. Spatiopora, briefly defined, is a ceramoporoid genus in which the characteristic wall structure is present, but mesopores and lunaria are practically absent. The zoarium is usually found incrusting the shells of Orthocerata, and the zooecia, as a whole, show great resemblance to the Trepostomata.
  • Genotype.—Spatiopora aspera Ulrich. Upper Ordovician (Maysville) of the Ohio Valley.

Nickles & Bassler (1900):

  • Spatiopora: Zoarium forming thin crusts, usually on Orthoceras; zoecia very short, nearly direct; apertures irregular, with blunt spines at the angles, no lunarium developed; elevated, elongated maculae usually a conspicuous feature.

Ulrich (1893):

  • Zoaria forming thin parasitic crusts upon foreign bodies, the shells of Orthoceras being the most favored. Surface even or with monticules. Zooecia short, with direct and more or less irregularly shaped apertures. Lunarium scarcely perceptible even in thin sections. Mesopores very few, usually absent, when present occurring chiefly as “maculae.” Interspaces often with large blunt spines (?acanthopores). Walls of zooecia moderately thin, with the characteristic structure pertaining to the family.

Foord (1883):

  • Incrusting, and forming very thin, large expansions, with a smooth or strongly tuberculated surface. Cells shallow, with oblong or irregular apertures. Interstitial cells sparingly developed. Spiniform tubuli generally of considerable size.

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