Phylum: Bryozoa
Class: Stenolaemata
Order: Trepostomatida
Family: Amplexoporidae
Genus: Amplexopora Ulrich, 1882
Cincinnatian Species: Amplexopora robusta, Amplexopora septosa

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Synonyms: Acanthotrypella Vinassa de Regny, 1921Type Species: Atactopora septosa (Ulrich, 1879) see Boardman 1960 (
History: (Nickles & Bassler, 1900)

  • 1882 Amplexopora Ulrich, Jour. Cincinnati Soc. Nat. Hist., V, p. 154.
  • 1883 Amplexopora Foord, Contr. Micro-Pal. Cambro.-Sil., p. 15.
  • 1889 Amplexopora Miller, North American Geol. Pal., p. 291.
  • 1890 Amplexopora Ulrich, Geol. Surv. Illinois, VIII, pp. 377, 450.
  • 1896 Amplexopora Ulrich, Zittel’s Textb. Pal. (Engl. Ed.), p. 278.
  • 1897 Amplexopora Simpson, Fourteenth Ann. Rep. State Geologist New York for the year 1894, p. 577.

Species found in the Cincinnatian (

  • Amplexopora ampla (Ulrich & Bassler, 1904)
  • Amplexopora columbiana (Ulrich & Bassler, 1904)
  • Amplexopora cylindracea (Ulrich & Bassler, 1904)
  • Amplexopora discoidea (Nicholson, 1874)
  • Amplexopora filiasa (d’Orbigny, 1850)
  • Amplexopora parva (Utgaard & Perry, 1964)
  • Amplexopora persimilis (Nickles, 1905)
  • Amplexopora petasiformis (Nicholson, 1881)
  • Amplexopora petasiformis welchi (James, 1882)
  • Amplexopora pumila (Cummings & Galloway, 1913)
  • Amplexopora pustulosa (Ulrich, 1890)
  • Amplexopora robusta (Ulrich, 1882)
  • Amplexopora septosa (Ulrich, 1879)
  • Amplexopora variabilis (Ulrich, 1890)

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Geologic Range

Common Paleoecology
Amplexopora is a genus of extinct stationary epifaunal filter feeders

Identification in Hand Sample:

  • Zoarium Morphology: Ramose, frondose, discoidal, massive, or encrusting; 5-10mm diameter
  • Zoecia: Prismatic, polygonal; Some species have zooecial linings
  • Mesozooids: Few to none
  • Monticules: None (Or very low)
  • Maculae: Composed of larger zooecial apertures & some mesopores

Geographic Occurrences

Species Differentiation

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Steven Holland (UGA Strat Lab, 2013):

  • Thin section information: Styles abundant: Some located in zooecial corners and extend throughout endozone. Others are located along zooecial walls and extend only partly through endozone; these often inflect zooecial walls into irregular pelatoid shapes; Cystoidal diaphragms and cystiphragms common in many species

Hannah Brame pers. comm. (2013):

  • A. septosa can be distinguished from A. robusta by its thicker cell walls, and the presence of mesopores

Treatise on Invertebrate Paleontology, Part G (1953):

  • Ramose; Zooecia with complete diaphragms. Acanthopores numerous.

Nickles & Bassler (1900):

  • Zoarium ramose, discoidal, or massy; zooecia prismatic, with diaphragms; acanthopores always present, variable in size and number

Foord (1883):

  • Ramose, free or incrusting. Cellular structure as in Monotrypella, excepting that more or less numerous spiniform tubuli are developed, which sometimes completely encirlcle the tubes./li>

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A. robusta

A. septosa