Synonyms: Orbiculothryris Woldfart, Bender, & Stein, 1968; Ptychopeltis Perner, 1903
Late Ordovician – Early Devonian
Schizocrania is an extinct genus of stationary low-level epifaunal suspension feeders
Identification in Hand Sample:
- Dorsal valve bears fine radiating costellate
- Ventral valve has concentric costellate, broad triangular opening.
- Pedicle opening broadly triangular, with straight margins
- Listrium small
Map point data provided by iDigBio.
Holland (UGA Strat Lab, 2013):
- Subcircular dorsal valve bears fine radiating costellate. Ventral valve has concentric costellate and broad triangular opening.
Treatise on Invertebrate Paleontology, Part H (2) (2000) :
- Shell subcircular to subtriangular, convexoplane to convexoconcave; dorsal valve ornamented by fine costellate; ventral valve less costellate or lacking costellate; ventral valve circular in outline; pedicle opening broadly triangular, with straight margins; listrium small; posterior margin of dorsal valve slightly thickened.
Mohawk Valley Fossils:
- Subcircular to subtriangular in outline, convexiplane to convexiconcave; brachial valve ornamented by fine costellae, pedicle valve by concentric fila, costellae may also occur. Pedicle valve circular in outline, straight, listrium small; posterior margin of brachial valve slightly thickened, pair of elongate subtriangular muscle scars in posterior third of valve, second pair of poorly defined scars near center of valve.
Caster, Dalve & Pope (1961):
- The inarticulate brachiopods are distinguished from the articulate forms by the absence of a hinge, a different musculature, and shells of calcium phosphate-chitin rather than calcium carbonate. In the Cincinnatian these may be frequently seen as thin, oval shells adhering to larger brachiopod shells (Petrocrania, Schizocrania), as chalky shells with minute punctae (pores) in the valves (Trematis) or as glossy, triangular shells (“Lingula”). Since the inarticulates appear in the Cambrian before the articulates, they are considered the evolutionary precursor of the articulates.
- Ventral valve with a marginal sinus, reaching nearly to the beak. Marginal sinus broad, triangular or semicircular, beak posterior.