Includes: Vinlandostrophia unicostata
- 1847 Delthyris lynx Hall, Pal. New York, vol. 1, pl. 32D, figs. 1 O, P, Q.
- 1871 Orthis laticostata James, Cat. Sil. Foss. Cincinnati Group, p. 10 (nomen nudem).
- 1873 Orthis (Platystrophia) biforata var. laticosta Meek, Pal. Ohio vol. 1, p. 116, pl. 10, fig. 4.
- 1875 Orthis laticostata Miller, Cincinnati Quart. Jour. Sci., vol. 2., p. 27.
- 1889 Orthis (Platystrophia) biforata var. laticosta Lesley, Geol. Surv. Pennsylvania, Rep. P. 4, p. 509, figs. 4a-d.
- 1892 Platystrophia biforata var. laticosta Hall and Clarke, Pal. New York, vol. 8, pt. 1, p. 223, pl. 5B, figs. 5, 8, 9 (not 6, 7).
- 1902 Platystrophia lynx var. laticosta Cumings and Mauck, Amer. Journ. Sci., ser. 4, vol. 14, p. 4.
- 1903 Platystrophia lynx var. laticosta Cumings (part), Amer. Journ. Sci., ser. 4, vol. 15, p. 28 (footnote), p. 29, figs e-e”’.
- 1903 Platystrophia laticostata Cumings (part), Amer. Journ. Sci., vol. 15, p. 30, 122.
- 1903 Platystrophia laticostata Foerste, Amer. Geol., vol. 31, p. 334.
- 1907 Platystrophia laticostata Grabau and Shimer, N.A. Index Fossils, vol. 1, p. 258.
- 1910 Platystrophia laticostata Foerste, Bull. Sci. Lab. Denison Univ., vol. 16, pl. 3, figs. 1a, b, 2.
- 1919 Platystrophia laticostata McEwen, Proceedings of the National Museum, vol. 56, p. 432-433, pl. 48, figs. 11-13.
Map point data provided by iDigBio.
- C5 Sequence (Waynesville)
- C4 Sequence (Arnheim)
- C3 Sequence (Corryville)
- C2 Sequence (Bellevue, Fairview: Fairmount)
- High fold with 4 plications; the sinus has 3
- Moderately compressed fold and deep sinus
- Lateral slopes flatly convex with 5 to 7 broad, angular plications
- Cardinal angles seldom less than 70 degrees
- Width commonly 30 mm., length 0.6-0.7 mm width
Vinlandostrophia laticosta from the McMillan Formation of Crestview Hills, Kentucky (OUIP 961)
Brame (pers. comm., 2013):
- Seven lateral plications; three plications in sulcus with the middle plication being the largest.
- Articulate brachiopod. Differs from P. hopensis in larger size and sharper, higher fold. Characteristic of the Bellevue and Corryville. (P. sublaticosta, a similar form, occurs in upper Fairmount.
- The entire range of forms normally referred to by most workers as either Platystrophia laticosta, P. unicostata, or P. cypha comprises a highly variable group having numerous intermediates that are sometimes difficult to identify with any degree of confidence. I interpret P. unicostata to be synonymous with P. laticosta. This interpretation is made because P. laticosta and P. unicostata are more similar in outline and profile and have approximately the same numbers of plications in the sulcus, on the fold, and on the flanks.
McFarlan (1931) :
- High fold; fold 4 plications, sinus 3; lateral plications reduced. Shell transverse, with high, moderately compressed fold and deep sinus; cardinal angles seldom less than seventy degrees. Lateral slopes flatly-convex with 5-7 broad, angular plications. Fold with four, sinus three plications, the lateral ones much reduced. Width commonly around 30 mm., length, 0.6-0.7 width.
- Platystrophia laticosta is a transverse species with a high compressed fold on which the plications are weak. The young of this species resemble Platystophia profundosulcata but the fold is not so high nor the sinus so deep. Index curves and the physiognomy of the shell indicate that Platystophia laticosta developed from one of the high fold variants of Platystrophia pauciplicata.
- Platystrophia laticosta has a transverse shell with seven plications on the lateral slopes. The fold is compressed and the sinus deep. The depth of the sinus is increased by elevation of the inner edges of the lateral slopes of the pedicle valve, which is the result of lateral compression.
- The slopes of the brachial (dorsal) valve have a convex curve from the front to the cardinal margin with the steepest part of the curve toward the hinge. The curve from the edge of the fold to the lateral margin is flatly convex.
- The chief distinction between Platystrophia laticosta and Platystrophia cypha is one of degree. Both have high compressed folds and deep sinuses, but there is less compression of the fold and less depth to the sinus in the former. The lengthwise convexity of the lateral slopes is also less in Platystrophia laticosta than in Platystrophia cypha.
- The lateral plications of the fold and sinus are weak, but they have never entirely disappeared. Specimens of Platystrophia cypha often have one or both of these plications entirely missing.
- Similar specimens occur in the Waynesville beds. The latter, are ventricose, more transverse, and bear nine instead of seven plications on the lateral slopes.
- Occurrences. Maysville group. Leipers formation: Nashville, Tennessee. Bellevue member: Maysville, Bullittsville, and Oldham County, Kentucky; Madison, Vevay, Lawrenceburg and Manchester, Indiana. Bellevue and Corryville beds: Cincinnati and elsewhere in Ohio.
- Plesiotypes. Cat. Nos. 48605, 50946, U.S.N.M.
- This is one of the most interesting and one of the least understood types of Platystrophia. It seems to be confined to American faunas, and occurs here only in the Cincinnati group of the Ohio valley, where is ranges through the Lorraine and reappears at the base of the Richmond formation. Its minute study, based upon hundreds of individuals, has, however, developed unsuspected relationships, which I shall now point out. Fig. 15 gives some idea of the variation of laticosta; e is a normal individual with one large (median) and two small (lateral) plications in the sinus. a has but one plication in the sinus and the fold is extremely elevated. b and d are intermediate between these two. In seeking the derivation of this type as in other types of Platystrophia the growth stages are of paramount importance.
- -Considering now the growth varices (fig. 16) it is evident that laticosta becomes progressively more transverse during ephebic stages, while costata becomes progressively less transverse; the early stages of the two being identical and also identical with the early stages of P. lynx.