Breviarca subovata

Geological Range

Albian.

Paleogeographic Distribution

Kansas.

Remarks

Original publication:

Scott, R. W. 1970. Paleoecology and paleontology of the Lower Cretaceous Kiowa Formation, Kansas. The University of Kansas Paleontological Contributions 52: 1-94.

Original description from Scott (1970, p. 60):

Shell small, subovate, nearly equilateral, equivalved. Beak inflated, projecting beyond hinge line. Dorsal margin moderate length, straight; anterior margin broadly, smoothly curved; ventral margin slightly convex; posterior margin broadly curved, somewhat truncate dorsally. Umbo smoothly rounded anteriorly and posteriorly. Ornament of faint growth lines.

Hinge line gently arched; denticles small, closely spaced, oblique to hinge line, strongest on dorsal corners, weakest directly under beak. External ligament narrow, lined with faint grooves normal to hinge line. Interior shell features unknown. Measurements of holotype, an incomplete RV: length 4.5 mm., height 4.8 mm., width 2.3 mm.; complete RV: length 4.5 mm., height 3.9 mm., width 2.1 mm."

Original remarks from Scott (1970, p. 60):

"This species differs from Breviarca habita by its noncancellate sculpture and subovate form; from B. angulata by its less angular posterior outline, more smoothly rounded umbonal ridges; from B. salinaensis (MEEK) by its less prominent beaks, more elongate form, and longer hinge line; and from B. siouxensis (HALL & MEEK, 1854) by its more rounded posterior. Three specimens from Loc. C3, unit 6, are similar to B. subovata but differ by less expanded umbo. They do not appear to be specifically distinct."

Stratigraphic Occurrences

Albian

Kiowa Formation (KS)