Bythopora gracilis

Phylum: Bryozoa
Class: Stenolaemata
Order: Trepostomatida
Family: Batostomellidae
Genus: Bythopora
Species: Bythopora gracilis (Nicholson, 1874)

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Stratigraphic Occurrences


Geographic Occurrences

Map point data provided by iDigBio.
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Sequences (Formations)

  • C3 Sequence (Terrill, Mt. Auburn, Corryville)
  • C2 Sequence (Tate, Bellevue)
  • McMillan Beds

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Identification in Hand Sample

  • Zoarium Morphology: Ramose; usually slender, but sometimes larger
  • Zoecia: Oblique apertures, narrowing above; acanthopores strong, usually one per zooecia (never numerous)
  • Mesozooids: Few
  • Monticules: Smooth
  • Maculae: N/A

Bythopora gracilis from the Fairview Formation of Covington, Kentucky (CMC 28174)

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Hannah Brame (pers. comm. 2013)

  • Above is the same description given for the genus. B. gracilis is characterized by larger zooecia and conspicuous apertures.

Elias & Condra (1957):

  • Cumings and Galloway (1915) made a more detailed investigation of laminated sclerenchyma in Trepostomata (=Monticuliporoids) from the earlier Paleozoic, as they observed the “histology of the trepostome walls under much higher magnification [up to X400] than has hitherto been employed and in longitudinal rather than in tangential sections” (1915, p. 359). They describe the laminae as being composed of “minute granules” (p. 360), which can be distinctly seen under magnification of X287, for instance, in Bythopora gracilis (Pl. 14, fig. 42). They state that in this bryozoans “the granules are larger than in most other forms, and hence can be seen distributed in more or less concentric bands.” In some walls they “are more closely concentrated in the axial region of the wall, and, when bands of granules from either side of the wall are present, they are often offset instead of continuing uninterruptedly across the median region of the wall” (p. 360).
  • Furthermore, the laminated tissue in the walls of some Trepostomata, shown in detailed sketches and mentioned in descriptions by Cumings and Galloway (1915), seems to differ from that in Fenestrata by a much denser spacing of the smaller laminae: circa 1 micron thick in Bythopora gracilis in which the granules of the laminae are “larger than in most other forms.”

McFarlan (1931)

  • Genus: Zooarium of smooth, slender branches, with small oblique zooecia, the apertures narrowing above and with channeled interspace. Mesopores few. Acanthopores never numerous.

Bassler (1906):

  • Bythopora gracilis forms long slender stems seldom over 3 mm. in diameter and characterizes the Fairview and McMillan formations, while the branches of B. meeki are seldom less than 6 or 7 mm. in diameter, and occur only in the Waynesville formation of the Richmond group.

Nickles & Bassler (1900)

  • Bythopora Miller and Dyer: Zoarium ramose, branches usually slender, sometimes of considerable size; zoecia practically without diaphragms; apertures oblique, narrowing above; interspaces caniculate; mesopores few; acanthopores comparatively strong, rarely more than one to each zooecium, sometimes wanting.

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