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- C5 Sequence (Waynesville)
Identification in Hand Sample
- Subequally biconvex shell
- Linear adductor scar that broadens anteriorly and that is not enclosed by diductor scars
- Narrow, rectangular muscular area of the pedicel valve
- Quadrate muscle scar
- Few costae with almost no tendency to bifurcate or intercalate except close to the margin
Austinella scovilli from the Waynesville Formation of Oregonia, Ohio (CMC 63684)
Holland (UGA Strat Lab, 2013):
- A plaesiomyid, with subequally biconvex shell, and a linear adductor scar that broadens anteriorly and that is not enclosed by diductor scars.
Langenheim, Jr. & Greife (1963):
- These scars, however, are the most important distinction by which Phleger distinguishes P. mazourkaensis Phleger from P. whitfieldi (N.H. Winchell) and Austinella scovillei (Miller). P. whitfieldi (N.H.Winchell) has a longer more complex muscle impression and A.scovillei (Miller) has a quadrate muscle scar.
Ross, Jr. (1959):
- Foerste (1912, pl. 8, fig. 8) shows that A. scovillei has few costae with almost no tendency to bifurcate or intercalate except close to the margin. Foerste (1912, p.g 131) differentiated A. scovillei from A. kankakensis and A. whitfieldi (which he believed synonymous) because it had approximately 40 rather than 60-70 costae.
- Some specimens are very closely comparable to A. scovillei as illustrated by Foerste (1912, pl. 8, figs. 8a-c). The more elongate, more narrowly hinged specimens bear a striking resemblances to the original figures of A. scovillei (Miller, 1882, pl. 1, figs. 5, 5a, 5b). According to Miller (1882, p. 40) the costae of that species increase by bifurcation, not by intercalation, and the pedicle valve is nearly flat. These two considerations seem to distinguish it from most of the Saturday Mountain forms.
- It is obvious that some selected specimens from the present collections could be identified as A. whitfieldi or A. scovillei. The evident variation between specimens suggests that these two may be varieties or subspecies of one species.
- A. delicata resembles A. scovillei in some respects but differs from it by its depressed or flat appearance in posterolateral areas of ventral valve. Exterior ornamentation of these two species is only similar at mesial portion, posterolateral costae being much crowded in the new species.
- Austinella scovillei is regarded as the genotype of the proposed group, Austinella. Figs. 8 B, and C, on plate VIII of this Bulletin, illustrate the narrow, rectangular muscular area of the pedicel valve, characteristic of this group. From the anterolateral angles of this area, branching vascular ridges diverge, only indistinctly indicated in the accompanying figures. An interior of the brachial valve is found in the collection of Dr. George M. Austin. Its hinge-area is flat, inclined at an angle of about 20 degrees with the plane passing parallel to the margins of the valve. Cardinal process of medium width, with a narrow groove down the middle posteriorly. A low median elevation extends from the thickened area between the crural plates forward between the areas where the muscle scars should be. Deep and broad dental sockets; no evidence of an extension of the crural plates beyond the anterior magin of the hinge-area.