Corynotrypa delicatula

Phylum: Bryozoa
Class: Stenolaemata
Order: Cyclostomata
Genera: Corynotrypa
Species: Corynotrypa delicatula (James, 1878)

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Originally: Hippothoa delicatula
Includes: Stomatopora proutana S.A. Miller (1882), Ropalonaria pertenuis, Stomatopora tenuissima, Stomatopora delicatulaHistory: (Under Stomatopora delicatula Nickles & Bassler, 1900)

  • 1878 Hippothoa delicatula James, Paleontologist, No. 1, p. 6.
  • 1882 Stomatopora proutana Miller, Jour. Cincinnati Soc. Nat. Hist., V, p. 39, pl. i, 4-4b.
  • 1890 Stomatopora proutana Ulrich, Jour. Cincinnati Soc. Nat. Hist., XII, fig 2c (p. 175).
  • 1893 Stomatopora proutana Ulrich, Geol. Minnesota, III, p. 117, pl. i, 8-12.
  • 1886 Rhopalonaria pertenuis Ulrich, Fourteenth Ann. Rep. Geol. Nat. Hist. Sur. Minnesota, p. 59.
  • Trenton (Stones River, Black River, Trenton) and Cincinnati (Utica, Lorraine, and Richmond): Various localities in Ohio, indiana, Kentucky, Tennessee, Illinois, Iowa, and Minnesota.

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Stratigraphic Occurrences


Geographic Occurrences

Map point data provided by iDigBio.
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Sequences (Formations: Members)

  • C6 Sequence (Elkhorn)
  • C5 Sequence (Liberty, Waynesville)
  • C4 Sequence (Arnheim)
  • C3 Sequence (Mt. Auburn, Corryville)
  • C2 Sequence (Fairview: Mount Hope, Fairmount)
  • C1 Sequence (Clays Ferry/Kope: McMicken, Southgate, Economy/Fulton)

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Identification in Hand Sample

  • Zoarium Morphology: Runner-like, usually encrusting in a branching pattern
  • Zoecia: Uniserial, narrow and long
  • Branches about one-tenth in diameter
  • Two to three zoarium in the length of a branch

Corynotrypa delicatula from the Waynesville Formation of Ohio (MUGM 22103)

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Steve Holland (2013, UGA strat lab):

  • Runner-like colonies: uniserial zooids encrusting in a branching pattern. Distinguishable from C. inflata by narrow and very long zooids, with side branches characterized by noticeably short zooids

Bassler (1911):

  • Original description. – “Polyzoary creeping, adnate, branching dichotomously, and sometimes anastomosing. Branches linear, about one-tenth of a line in diameter. Cells uniserial, each growing by a pointed base from the cell below, and expanding gradually to the mouth; two or three cells in the space of a line. Apertures terminal, elevated, and nearly or quite the diameter of the cells and places on their front face.”
  • To James’s original description the following remarks may be added. Strictly speaking, the zooecia do not gradually expand from a pointed base, but, as indicated in the several sets of figures illustrating this species, the slender part of the zooecium, here styled the stolon, is of uniform diameter from some distance in the elongated forms. The gradual increase in diameter begins with the zooecium proper. The dimensions for the various forms of the species are as follows: The zooecia in the slender, elongate form shown in figure 6 average seven in 8 mm., while each, including the stolon, is from 1 mm. at its greatest diameter. The slender proximal or stolonal portion in this form, as well as the others to be mentioned, is about 0.04 mm., while the aperture itself if slightly wider, averaging 0.05 mm. In figure 7 the short form of the species is illustrated. Here the measurements are practically the same as those given above, except that the zooecia very from 0.6 mm. to 0.8 mm. in length, and 8 to 10 occur in 5 mm. Several unusually large zooecia are illustrated in figure 7d, but such specimens are of rare occurrence and even here the measurements are all in proportion to those of the typical specimens. In all of these various specimens, the length of the zooecium proper is approximately the same and its angle of divergence remains about 15 degrees.
  • The considerable variation in the length of the stolon of this species has been discussed before and specific differences based upon this character have not been maintained, as noted in the synonymy above. At certain horizons, particularly in the McMillan formation at Cincinnati, Ohio, very luxuriant growths of C. delicatula are found and it is in such specimens that the greatest variation is exhibited.
  • Miller applied the name Stomatopora proutana to the very elongate form from the Corryville bed at Cincinnati, while specimens with the same characters but coming from the lower part of the Eden shale were described as S. tenuissima by Ulrich. The form with short zooecia was named Rhopalonaria pertenuis by Ulrich but later placed by him as a synonym of S. proutana Miller. Nickles and Bassler recognized James’s name but considered S. tenuissima of sufficient value to rank as a variety. The present study indicates that this last form has the zooecium typical of the species and differs only in its greatly elongated stolon.

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