- 1908 Playstrophia lynx var. laticosta Cumings, 32d. Ann. Rep. Dep. Geol. Nat. Res. Indiana, pl. 35, figs. 2, 2a, 2b; Amer. Journ. Sci., ser. 4, vol. 15, p. 32, fig. 17bb.
- 1910 Platystrophia clarksvillensis Foerste, Bull. Denison Univ., 16, p. 65, pl. 3, figs. 3, 4.
- 1919 Platystrophia clarksvillensis McEwen, Proceedings of the National Museum, vol. 56, p. 422, pl. 45, figs. 1-4.
Map point data provided by iDigBio.
- C5 Sequence (Waynesville)
Identification in Hand Sample
- 7-9 plications on the lateral slopes
- Plications of the fold and sinus nearly equal size
- Specimens as wide as 25 mm occur, with the average specimen 20 mm in size
- Cardinal extremities acute; with one side often equaling 70 degrees
Vinlandostrophia clarksvillensis from the Arnheim Formation of Brookville, Indiana (OUIP 1036)
Brame (pers. comm., 2013):
- Three equal plications on sinus; eight or nine lateral plications.
- Platystrophia clarksvillensis has the highest percentage of articulated specimens among the orthids, a fact attributed to the hydrodynamic stability of this species and the interlocking of the valves by the plicae around the commissure. The significantly greater ratio of articulated to disarticulated specimens of Platystrophia clarksvillensis relative to other orthids suggests that the valves of this species may have been more difficult to disassociate than other orthid species with a deltidiodont hinge. Alate (winged) brachiopods such as P. clarksvillensis are much more stable with the valves erect and the commissural plane oritented parallel to the current than are species that are dorsi-biconvex, ventri-biconvex, or plano-convex and have comparatively shorter hinge lines.
- P. clarksvillensis Foerste has a longer hinge line and fewer costae on the flanks.
- A species of the P. laticosta type but, with narrower and more numerous plications on the lateral slopes (7-9), the plications of the fold and sinus of more nearly equal size with the resulting relatively broader and less angular fold and sinus. The lateral slopes are somewhat fuller, giving less prominence to the fold.
- Specimens 25 mm wide occur, but the average is nearer 20 mm. Specimens with nearly rectangular postero-lateral outlines predominate, but in some the postero-lateral angles equal 70 degrees; as a rule, however, only on one side.
- Locality and Horizon. Widely distributed in the Waynesville of Ontario. On Manitoilin island it occurs at Gore Bay, Kagawong, south of Little Current, Manitowaning, and Clay cliffs (No. 8508), also at Meaford, Oakville, and Streetsville; in Quebec in the Waynesville at St. Hilaire, in erratic blocks at St. Hugues, in the Nicolet River section, and on Snake island. The species was described originally from the Waynesville of Ohio, Indiana, and Kentucky.
- This is a transverse species which bears a marked resemblance to Platystrophia laticosta. It is narrower than that species and has more closely spaced, narrower, and more numerous plications on the slopes, there being seven to nine. It differs, also, from Platystrophia laticosta in that the slopes are somewhat fuller, which reduces the height of the fold. The lateral plications of the fold and sinus vary from somewhat weaker than the median plications to about equal to them in strength. The hinge line is generally greater in length than the width across the middle, but it may equal it or be somewhat less than the width.
- Specimens with a long hinge line have the same general aspect as Platystrophia cumingsi, new species, but the latter has a longer hinge and has more numerous plications on the slopes.
- Measurements. 25 mm along the hinge line, 23 mm wide across the middle, 16 mm high, 15 mm thick, 11 mm sinal width, 10 mm sinal depth, 4.5 mm fold depth.
- Occurrence. Richmond group: Arnheim Formation: Seatonville and Clark, Kentucky; Waynesville Formation: Waynesville and Oregonia, Ohio; Weisburg and numerous other localities in Indiana.
- Plesiotypes. Cat. Nos. 65713, 65726, U.S.N.M.