Glyptorthis insculpta

Classification
Phylum: Brachiopoda
Class: Rhynchonellata
Order: Orthida
Family: Glyptorthidae
Genus: Glyptorthis
Species: Glyptorthis insculpta (Hall, 1847)

Taxonomic Details

Formerly: Orthis insculpta

Stratigraphic Occurrences

G.Insculpta

Geologic Range
Lower Ordovician – Middle Silurian

Geographic Occurrences

		
Map point data provided by iDigBio.

Stratigraphic Distribution

Sequence (Formations)

  • C5 Sequence (Liberty and Waynesville)

Identification in Hand Sample

  • Elevated beak
  • Depressed-convex dorsal valve
  • Fine, elevated radii on the umbo
  • Valves are marked with very clear transverse lines
  • Checkerboard pattern created by striae and growth lines

Glyptorthis insculpta from Waynesville formation of Warren county, Ohio (OUIP 1480)

Published Description

Wright & Stigall (2014):

  • Emended from Hall (1847) and Schuchert & Cooper (1932). Shell large; subquadrate; concentric ornamentation weakly to strongly lamellose; costal density low to moderate. Ventral muscle scars large with lateral and anterior deflections; narrowing near the hinge teeth. Ventral diductor scars separated by a medial septum; adductor scars of variable width, widening towards the anterior. Dorsal cardinal area high, extending over the hinge line; umbonal angle less than 150 degrees.

Davis (1998):

  • Articulate brachiopod. Differs from similar species by the reticulate pattern produced on the surface by the intersection of the coarse radial striae and the concentric growth lines. Waynesville and basal Liberty

Foeste (1924):

  • Species relatively small. Brachial (dorsal) valve with distinct median depression along entire length. Pedicle (ventral) valve with relatively large, diverging hinge-area which causes its beak to stand away from that of the brachial (dorsal) valve. Specimens numerous with forty to forty-five plications of approximately equal prominence; but there are specimens in which twenty to twenty-five of the plications make their appearance within 7 or 8 mm from the beak, additional plications being intercalated anteriorly, but the primary striae remaining dominant. This causes some specimens to appear more coarsely plicated than others, but they are regarded merely as more robust individuals. The most conspicuous feature is the concentric striae which are sharply elevated and nearly equidistant.
  • Locality and Horizon. Hebertella insculpta was described originally from the Blanchester division of the Waynesville where it occurs both in the top and bottom layers. It is known also a short distance above the base of the Liberty in Ohio. At the Waynesville horizon it occurs in Ohio, Indiana, and Kentucky. In Richmond strata from Tennessee, Illinois, Wisconsin, Minnesota, and Iowa where it tends to be more finely plicated. In the Girvan district of Scotland, Glyptorthis is represented by Orthis (Hebertella) balclatchiensis Davidson, from the lowest or Balclatchie stage of the Caradocian formation. In American strata Glyptorthis bellarugosa (Conrad) is widespread in the Black River formation of the upper Mississippi Valley, as far south as central Kentucky. A similar form occurs in the Valcour member of the Chazyan on Valcour island, New York.

Hall (1847):

  • Shell resupinate; dorsal valve depressed-convex; beak elevated, not incurved; cardinal line less than the width of the shell; area short; surface marked by fine elevated radii which are bifid on the umbo, and again regularly bifid or trifid towards the margin of the shell; transversely marked by strong elevated concentric lines, which are particularly prominent between the radii, giving an indented or sculptured appearance to the surface; interior of the dorsal valve showing marks of the visceral impression, which is peculiarly sculptured.
  • This species, of which a single valve has been seen, is so peculiarly marked as not to be mistaken among the all the other species of Orthis in the lower rocks. The cavity under the foramen is large and deep, marked on its lower and outer extremities by two pointed sacs, and margined by a thickening of the shell round: the visceral impression on the outside of this cavity is of a double auricular form and sculptured by curved elevated lines. The inner margin of the shell is impressed by the outer radii.
  • This very peculiar form is usually associated with the following forms in the blue limestone of Ohio. Its very beautiful sculpture, both internally and externally, is sufficient to distinguish it from all other species in the rock.