Phylum: Bryozoa
Class: Stenolaemata
Order: Trepostomatida
Family: Heterotrypidae
Genus: Petigopora Ulrich, 1882

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Type Species: Chaetetes petechialis (Nicholson, 1875)
Synonyms: Dekayella Ulrich, 1882Species found in the Cincinnatian (

  • Petigopora petechialis (Nicholson, 1875)

Taxonomic History (Nickles & Bassler, 1900)

  • 1882 Petigopora Ulrich, Jour. Cincinnati Soc. Nat. Hist., V, p. 155.
  • 1889 Petigopora Ulrich, Contr. Micro-Pal. Cambro-Sil., Part II, p. 34.
  • 1889 Petigopora Miller, North American Geol. Pal., p. 314.
  • 1890 Petigopora Ulrich, Geol. Sur. Illinois, VIII, p. 372.
  • 1896 Petigopora Ulrich, Zittel’s Textb. Pal. (Engl. ed.), p. 274.
  • 1897 Petigopora SImpson, Fourteenth Ann. Rep. State Geologist New York for the year 1894, p. 563.

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Geologic Range

Stratigraphic Occurrences

Geographic Occurrences

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Sequences (Formations)

    • C2 Sequence (Fairmount, Bellevue, McMillan)
    • C3 Sequence (Corryville, McMillan, Mt. Auburn)
    • C4 Sequence (Arnheim)

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Identification in Hand Sample:

  • Zoarium Morphology:
  • Zoecia: Short budding directly from the substrate.
  • Mesozooids: Rare, rounded-polygonal in cross-section.
  • Monticules:
  • Maculae:

Petigopora asperula Uknown location. (CMC 14304)

Species Differentiation

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Holland (UGA Strat Lab 2013):

  • Petigopora is a small, circular encruster, with an internal structure like Dekayia.

Ulrich & Bassler (1905):

  • The ascertain whether or not certain or all of the species referred to this genus are dwarfed mutations or possibly only young stages of normally ramose or massive forms of other genera of the Heterotrypidae, has been a most difficult task. The problem, moreover, still confronts us and its solution seems as difficult as ever. We tried to show, for instance, that P. gregaria was merely the beginning of a secondary layer of zooecia on branches of species of Dekayia, but when it was found growing on all sorts of Bryozoa, and that it always maintained a reasonably definite size, we realized that some other explanation of its existence was in order. So we let it stand and with it the genus. The zooecial structure of P. asperula Ulrich again is essentially the same as that of the associated Dekayia appressa, but among the hundreds of specimens of these species that we have collected there is none to connect them. Finally, P. petechialis, or species resembling it, occurs almost throughout the Mohawkian and Cincinnatian groups, generally in association with other Heterotrypidae. We have, however, found zoaria of Petigopora in horizons from which no other similar Heterotrypoids are known. At present, we can regard such a fact only as indicating that these small incrustations are species by themselves.

Nickles & Bassler (1900)

  • Zoarium forming small, circular, incrusting patches; zooecia direct, with few or no diaphragms; acanthopores rather large, of one kind only; mesopores wanting.

Cincinnati Society of Natural History Vol. 6 (1883)

  • Petigopora gregaria Ulrich, was described as parasitic, the corallum consisting of patches from one to three lines in diameter and one-fourth of a line thick: a narrow smooth or wrinkled membrane forms the outer margin, which is slightly elevated: surface smooth; apertures equal: no interstitial cells; spiniform corallites inconspicuous; walls thin and flexuous; tabulae apparently wanting. It occurs at Cincinnati.

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