Phylum: Bryozoa
Class: Stenolaemata
Order: Trepostomatida
Family: Heterotrypidae
Genus: Heterotrypa Nicholson, 1879
Species: Heterotrypa frondosa, Heterotrypa milleri, Heterotrypa parvulipora, Heterotrypa subfrondosa, Heterotrypa ulrichi

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Type Species: Monticulipora frondosa (d’Orbigny, 1850)
Synonyms: Dekayella Ulrich, 1882Species found in the Cincinnatian (Bryozoa.net)

  • Heterotrypa cystata (Cumings, 1901)
  • Heterotrypa foliacea (Ulrich & Bassler, 1904)
  • Heterotrypa frondosa (d’Orbigny, 1850)
  • Heterotrypa inflecta (Ulrich, 1890)
  • Heterotrypa lobata (Cumings)
  • Heterotrypa microstigma (Cumings & Galloway, 1913)
  • Heterotrypa obscura (Ulrich, 1883)
  • Heterotrypa robusta (Foord, 1884)
  • Heterotrypa paupera (Ulrich, 1883)
  • Heterotrypa singularis (Ulrich, 1890 )
  • Heterotrypa solitaria (Ulrich, 1883)
  • Heterotrypa subfrondosa (Cumings, 1902)
  • Heterotrypa subpulchella (Nicholson, 1875)
  • Heterotrypa subramosa (Ulrich, 1879)
  • Heterotrypa ulrichi (Nicholson, 1881)

Taxonomic History (Nickles & Bassler, 1900)

  • 1879 Heterotrypa (in part) Nicholson, Pal. Tabulate Corals, p. 291.
  • 1881 Heterotrypa Nicholson, Genus Monticulipora, pp. 101, 103.
  • 1882 Heterotrypa Ulrich, Jour. Cincinnati Soc. Nat. HIst., V, p. 155; ibid., VI, 1883, p. 83.
  • 1883 Heterotrypa Foord, Contr. Micro-Pal. Cambro-Sil., p. 20.
  • 1890 Heterotrypa Ulrich, Geol. Sur. Illinois, VIII, pp. 371, 413.
  • 1893 Heterotrypa Ulrich, Geol. Minnesota, III, p. 267.
  • 1896 Heterotrypa (in part), Zittel’s Textb. Pal. (Engl. ed.), p. 104.
  • 1896 Heterotrypa Ulrich, Zittel’s Textb. Pal. (Engl. ed.), p. 273.
  • 1897 Heterotrypa Simpson, Fourteenth Ann. Rep. State Geologist New York for the year 1894, p. 578.

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Geologic Range

Stratigraphic Occurrences

Geographic Occurrences

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Sequences (Formations)

  • C5 Sequence (Lower Whitewater, Waynesville)
  • C4 Sequence (Arnheim)
  • C3 Sequence (Mt. Auburn, Corryville)
  • C2 Sequence (Bellevue, Fairview: Fairmount, Mt. Hope)
  • C1 Sequence (Clays Ferry/Kope: McMicken)

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Identification in Hand Sample:

  • Zoarium Morphology: Frondescent to ramose (sometimes encrusting)
  • Zoecia: Subcircular to subpolygonal in cross section; acanthopores small, common
  • Mesozooids: Abundant (generally); sparse to common, scattered, subpolygonal to subcircular in cross section
  • Monticules: Present
  • Maculae: Common, low, composed of a combination of clusters of mesopores or large polymorphs.
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Holland (UGA Strat Lab, 2013)

  • Heterotrypa is frondose, ramose, or less commonly encrusting, and it often bears monticules. Typically, endozone has few diaphragms, but diaphragms are commonly regular and closely spaced in exozone. Walls vary in thickness. Mesozooids are often common, but may be absent, and are commonly beaded proximally and tend to terminate within exozone. Heterotrypa has two types of styles. One type occurs within all or part of exozone, lies between zooecial corners, and may be offset from the wall. The other type is larger, starts in both endozone and exozone, lies at zooecial corners, and typically terminates within the exozone

Karklins (1984)

  • Boardman and Utgaard (1966) discussed the zoarial development of Heterotrypa and revised the concept for the genus. The definition of the genus Heterotrypa as given by Boardman and Utgaard (1966) is followed here.

Treatise on Invertebrate Paleontology, Part G (1953)

  • Frondescent. Mesopores closely tabulate; acanthopores of one kind only.

McFarlan (1931)

  • Genus: Zooarium frondescent, acanthopores small, mesopores abundant, diaphragms abundant.

Nickles & Bassler (1900):

  • Zoarium erect, frondescent, or ramose; zooecia with numerous diaphragms; acanthopores small, of one kind; mesopores variable in number, generally abundant, sometimes wanting.

Foord (1883):

  • Zoarium growing from an expanded base, attached to foreign objects, upward into simple, often undulated or irregularly inosculated fronds, and occasionally into flattened branches. Cell-apertures varying in shape from polygonal to circular. They are separated from each other by walls or interspaces, which may be comparatively thin, or nearly as thick as their own diameter. Interstitial cells from few to very numerous, always angular or sub-angular. Spiniform tubuli small, usually numerous (sometimes excessively so), occasionally inflecting the walls, and giving the cell apertures an irregularly petaloid appearance. Internally we find that the walls of the tubes are more or less thickened as they enter the ‘mature’ region, and apparently amalgamated with one another. The diaphragms are straight, of one kind only, more numerous in the interstitial tubes than in the proper zoaecia, and always more crowded in the ‘mature’ regions than in the ‘immature’ or axial regions.

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H. frondosa

H. milleri

H. parvulipora

H. subfrondosa

H. ulrichi