Homotrypa flabellaris

Phylum: Bryozoa
Class: Stenolaemata
Order: Trepostomatida
Family: Mesotrypidae
Genus: Homotrypa
Species: Homotrypa flabellaris (Ulrich, 1890)

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Also called: Monticulipora flabellarisTaxonomic History (Nickles & Bassler, 1900)

  • 1890 Homotrypa flabellaris Ulrich, Geol. Sur. Illinois, VIII, p. 411, pl. xxxii, 3-3c.
  • 1895 Monticulipora flabellaris J.F. James, Jour. Cincinnati Soc. Nat. Hist., XVIII, p. 75.

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Stratigraphic Occurrences


Geographic Occurrences

Map point data provided by iDigBio.
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Sequences (Formations)

  • C6 Sequence (Upper Whitewater, Elkhorn)
  • C5 Sequence (Lower Whitewater, Liberty, Waynesville)
  • C4 Sequence (Arnheim)
  • C2 Sequence (Fairview: Fairmount)

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Identification in Hand Sample

  • Zoarium Morphology: Frondose, branching; flattened, expanded branches
  • Zoecia: Oblique; thin walled (sometimes crenulated)
  • Mesozooids: Few, generally clustered
  • Monticules: None
  • Maculae: Larger cell apertures
Homotrypa obliqua

Homotrypa flabellaris from Waynesville Formation of Franklin County, Indiana(CMCIP 21305)

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Davis (1998)

  • Forms flat expanded branches without monticules. Internally, this species differs from similar species by having numerous mesopores concentrated in small patches (maculae) and few diaphragms in the immature part of the zooecia.

Bassler (1903)

  • This species with its varieties has quite a range, both geologically and geographically, specimens being found, generally abundantly, in the Lorraine and Richmond at many localities in the Mississippi Valley. The species was described from specimens found in the Richmond at Wilmington, Illinois. The figured sections illustrating the internal structure were prepared from a colony in which the mature region was not fully developed. Mature specimens show a moderately crowded series of cystiphragms and diaphragms in the peripheral region. If the large acanthopore was omitted, it would show the characters seen in a vertical section of this species. The specific characters are the flabellate growth, smooth surface, nine zooecia in 2 mm, few small acanthopores, mesopores tabulated, numerous in the maculae and not uncommon among the ordinary zooecia, a moderate number of diaphragms in the axial region and a well-developed series of diaphragms and cystiphragms in the peripheral region.[/accordion] [/accordions]