Prasopora simulatrix

Phylum: Bryozoa
Class: Stenolaemata
Order: Trepostomatida
Family: Monticuliporidae
Genus: Prasopora
Species: Prasopora simulatrix (Ulrich, 1886)

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Type species: Monticulipora mammullata (d’Orbigny, 1850)

Taxonomic History (Nickles & Bassler, 1900)

  • 1886 Prasopora simulatrix Ulrich, Fourteenth Ann. Rep. Geol. Nat. Hist. Sur. Minnesota, p. 85.
  • 1893 Prasopora simulatrix Ulrich, Geol. Minnesota, III, p. 245, pl. xvi, 1-10.
  • 1896 Prasopora simulatrix Ulrich, Zittel’s Textb. Pal. (Engl. ed.), fig. 452 (p. 273).
  • 1897 Prasopora simulatrix Simpson, Fourteenth Ann. Rep. State Geologist New York for the year 1894, figs. 171, 172 (p. 587).
  • 1890 Prasopora lycoperdon Ulrich, Geol. Sur. Illinois, VIII, fig. 7a-b (p. 318).
  • 1895 Monticulipora selwynii (not of Nicholson) J.F. James, Jour. Cincinnati Soc. Nat. Hist., XVIII, p. 86.

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Stratigraphic Occurrences


Geographic Occurrences

Map point data provided by iDigBio.
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Sequences (Formations)

  • C1 Sequence (Clays Ferry/Kope)

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Identification in Hand Sample

  • Zoarium Morphology: Flattened discoidal to subconical; occasionally lobate; wrinkled epitheca on under surface; base concave; diameter usually 2-10cm
  • Zoecia: Subcircular; 7-8 in 2mm; generally surrounded by angular mesopores; acanthopores present, but not numerous or strong
  • Mesozooids: Small, angular abundant
  • Monticules:
  • Maculae: Conspicuous with larger apertures and more numerous mesopores

Diagnosis:Colloquially referred to as “Chocolate Drop” bryozoans, because the morphology of their zoaria resembles the shape of a Hershey’s Kiss.

Prasopora simulatrix from the Eden Formation of Fort Mitchell, Kentucky (OUIP 17)

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Karklins (1984):

  • Discussion of the differences between P. falsei and P. simulatrix: Remarks— Prasopora falesi characteristically has distinct small and relatively large styles as well as abundant mesozooecia throughout intermacular areas and in clusters in maculae and proximately onlapping cystiphragms in regular series, extending two-thirds to three-fourths the circumference of autozooecia (cystiphragm type 1 of Ross, 1967a, p. 406) in most parts of exozones. Cystiphragms, however, occasionally occur singly and are restricted laterally in outer exozones of autozooecia of P. falesi. P. falesi is closely related to P. simulatrix Ulrich. The species are similar in their hemispherical growth habits, the shape and size of their autozooecia, the distribution of their basal diaphragms, the shape and general arrangement of their cystiphragms, and their polymorphism. P. falesi differs from P. simulatrix, however, in having distinct styles throughout exozones. Styles in P. simulatrix (acanthopores of Bork and Perry, 1968b, p. 1058) are commonly lacking, or are exceedingly small and occur, sparingly, only in peripheral parts of zoaria (the acanthoporelike structures of Ross, 1967a, p. 412). P. falesi and P. simulatrix both have cystiphragms of type 1 of Ross (1967a). P. falesi, however, differs from P. simulatrix in having cystiphragms that occasionally occur singly or in pairs and are locally restricted laterally. Both species have numerous mesozooecia that partly separate autozooecia, but P. falesi has fewer mesozooecia than P. simulatrix. P. falesi has approximately 20 mesozooecia per unit of area in exozones (tables 18-20), whereas P. simulatrix has approximately 27 (Bork and Perry, 1968b, tables 12-14).

McFarlan (1931):

  • Zooarium flattened discoidal to subconidal, diameter usually 2-10 cm, base more or less concave. Zoarium occasionally lobate. Apertures subcircular, 7-8 in 2mm, more or less in contact except at the junction angles. Maculae conspicuous, of larger apertures and more numerous mesopores. Acanthopores absent. Diaphragms closely spaced, about ½ tube diameter apart, accompanied by a series of cystiphragms lining the zooecial walls

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