Species: Schizocrania filosa (Hall)
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Map point data provided by iDigBio.
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- C3 Sequence (Corryville)
- C2 Sequence (Bellevue, Fairview: Fairmount)
- C1 Sequence (Clays Ferry/Kope: Economy/Fulton)
Identification in Hand Sample
- Shell subcircular in outline
- Pedicle valve is flat or convex and apex is subcentral
- The surface of pedicle valve is concentrically wrinkled and the surface of the brachial valve is radially striated
- Attach by cementation to some hard substrate, often another organism’s shell
Schizocrania filosa from the McMillan Formation of Cincinnati, Ohio (OUIP 488)
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- Inarticulate brachiopod. Encrusting upon other brachiopods/hardground. Dorsal valve. Note fine striations and convexity of valve. Fairmount through Oregonia
Lockley & Antia (1980):
- Other members of the family, e.g. P. hornyi Havlicek and D. grandis Barrande, are commonly attached to conularids which are considered by Havlicek (1972) to have been mobile during life, and the American species S. filosa Hall frequently attached to the brachiopod Rafinesquina (e.g. Cooper 1956 and Rowell in Williams et al. 1965). With respect to trematidnautiloid associations, it is intriguing to note that Titus and Cameron (1976) record S. filosa only in their deep-water Geisonoceras (Orthocerida) community.
- Shell is subcircular in outline. The pedicle valve is flat or convex and apex is subcentral. Pedicle notch is deep and wide with its apical angle occupied by a plate. The brachial valve is larger than the pedicle valve and is convex with a terminal beak and two sets of muscle scars on the interior. One pair of strong posterior adductor scars are separated by a low median ridge, diverging from the beak and in some cases faintly divided transversly and a second pair of faint, minute scars are centrally placed. The surface of pedicle valve is concentrically wrinkled and the surface of the brachial valve is radially striated. Can be distinguished from other Ordovician brachiopods by the fine thread-like striae and the terminal beak on the brachial valve. Epifaunal, filter feeders that attach by cementation to some hard substrate. Substrate is often another organism’s shell. Schizocrania has been found cemented to conularids (Harland and Pickerill, 1987) and to orthoconic nautiloids (Lockley and Anita, 1980)
- This Schizocrania filosa is oval in form, narrower posteriorly. The length of a well preserved specimen is 16 mm., its width is 15 mm., and the convexity of the dorsal valve is about 3 mm. Radiating striae numerous, about 12 in a width of 2 mm. Posterior adductor scars large, similar in form to those represented in figure 26, plate IV G, in the Paleontology of New York, vol. VIII. By Hall and Clarke from the Maysville formation at Cincinnnati, Ohio. The anterior edge of the scars extends to 6.5 mm. from the beak. The anterior adductors are small, and are 8 mm. from the beak, and 4 mm. from each other.
Hall & Whitfield (1875):
- Shell orbicular, or very slightly ovate, the beak of the upper or free valve projecting a little beyond the limits of the circle, giving a somewhat greater diameter along the median line than in a transverse direction. Free valve moderately convex, the central region being the most prominent. Attached valve discoid, very thin, deeply and broadly notched on the posterior side; the notch not extending quite to the center of the valve; occupying nearly one quarter of the circumference of the valve on the outer margin; border of the notch thickened, especially at the base, which is rounded, and the center marked by two proportionally large, elongate, ovate, diverging muscular prominences, leaving corresponding pits on the casts of the shell, or on exfoliated specimens; situated just below the beak, and extending to nearly or quite one-fourth of the length of the valve from the apex. There are also two other muscular impressions somewhat smaller in size, circular in form, and situated near the middle of the valve below the extremities of the ovate imprints, and slightly more distant from each other. Beneath the beak there is a slight thickening of the cardinal border. The muscular markings of the lower valve have not been observed. Surface of the shell of the convex valve marked by fine, even, thread-like, radiating striae; increased both by division and implantation, and gradually increasing in strength toward the border of the shell; the interspaces where the shell is perfectly preserved are flattened, the striae appearing as raised lines on the surface. The attached valve is strongly marked by irregular concentric undulations circling the valve parallel to the margin, but interrupted at the border of the notch.