Rafinesquina nasuta

Classification
Classification
Phylum: Brachiopoda
Class: Strophomenata
Order: Strophomenida
Family: Rafinesquinidae
Genus: Rafinesquina
Species: Rafinesquina nasuta

Taxonomic Details

Taxonomic History:

  • 1842 Strophomena nasuta Emmons, Geol. New York, Rept. 3rd Dist., p. 403, fig. 3.
  • 1847 Leptaena alternata Hall, Pal. New York, 1, p. 286, pl. 79, figs. 2a-c.
  • 1914 Rafinesquina nasuta Foerste, Bull. Sci. Lab. Denison Univ., 14, p. 263, pl. 3, figs 2A, B; pl. 4, fig. 2 C.

Stratigraphic Occurrences

R.nasuta_strat

Geographic Occurrences

		
Map point data provided by iDigBio.

Stratigraphic Description

Sequences (Formations)

  • C3 Sequence (Corryville)

Identification in Hand Sample

  • Species has an anterior extension which gives the shell a triangular outline
  • Ventral valve gently convex over the body of the shell
  • Length somewhat greater than width (40-50 mm)

Rafinesquina nasuta from the McMillan formation of Georgetown, Ohio (OUIP 825)

Published Description

Davis (1998):

  • Articulate brachiopod. Like R. ponderosa but with anterior extension (may even take the shape of a minor fold) which gives the shell triangular outline. Corryville.

Copper (1996):

  • In addition, three other Ordovician strophomenid species were used in the soft substrate experiment, in order to broaden the morphological range under examination: Rafinesquina nasuta, similar in shape to R. alternata, but with a medial projection of the geniculate, anterior margin; Leptaena richmondensis, which is small, oblate, always geniculate, with pronounced, regose growth lines; and Strophomena planumbona, which is small, oblate, and never geniculate, but varies in valve convexity.

McFarland (1931):

  • Distinguished from R. alternata by the nasute anterior outline. Width commonly around 40-50 mm. Length somewhat greater. McMillan beds of the Cincinnati region.

Foerste (1924):

  • Ventral valve gently convex over the body of the shell; strongly, but not abruptly, curved downward along the anterior margin so that its convexity there reaches 7 to 10 mm. In different specimens lateral sides vary greatly, from diverging to converging anteriorly. Anterior to the middle, all shells tend to converge with somewhat straightened antero-lateral sides, and to be produced along the median part of the anterior margin in a nasute manner. This anterior nasute prolongation in many cases springs from a base 17 or 18 mm wide, but there are numerous specimens with nasute prolongations originating at bases 8 to 10 mm in width.
  • Locality and Horizon. The type described by Conrad was found at Rome, New York, at a much higher horizon than the specimens here figured from Pulaski. Lateral sides of this type parallel, and antero-lateral sides meet anteriorly so as to give the general outline of the shell a pentagonal effect. The nasute prolongation anteriorly was barely 3 mm wide at its base.