Richmondoceras brevicameratum

Phylum: Mollusca
Class: Cephalopoda
Order: Orthocerida
Family: Orthoceratidae
Genus: Richmondoceras
Species: Richmondoceras brevicameratum Frey, 1995

Stratigraphic Occurrences

B. amoenum_strat

Geographic Occurrences

Map point data provided by iDigBio.

Stratigraphic Description

Sequences (Formations)

  • C5 Sequence (Saluda)

Identification in Hand Sample

  • Distinguished by its short camerae
  • Midventral siphuncle segments
  • Weak development of both endosiphuncular and cameral deposits
  • Shell exterior smooth
  • Circular in cross section with straight, transverse sutures

Published Description

Frey (1995):

  • Diagnosis. – Medium to large, slender, gradually expanding orthoconic longicone distinguished by its short camerae, expanded, compressed, midventral siphuncle segments, and weak development of both endosiphuncular and cameral deposits.
  • Description. – Medium to large (up to 73.5 cm in length and 6.5 cm in diameter), slender, gradually expanding (apical angle 6 degrees) orthoconic longicone; circular in section with straight, transverse sutures. Cameral chambers short having cameral lengths decreasing with ontogeny from one-sixth the diameter of the shell at a shell diameter of 20 mm to one-ninth the diameter of a shell at a shell diameter of 40 mm. Adoralmost septa in large specimens becoming approximate with ontogeny. Body chamber long, tubular, at least one-fifth the total length of the shell. Aperture unknown. Shell exterior apparently smooth.
  • Siphuncle position ranging from subcentral at shell diameters of 20 mm or less, to midventral at shell diameters of 50 mm. Siphuncle segments greatly expanded the length of the phragmocone, ranging from highly compressed at a shell diameter of 25 mm to compressed at a diameter of 50 mm. Segment diameter ranging from one-third the diameter at shell diameters of 20 mm or less to slightly less than one-sixth the diameter of the shell at a diameter of 50 mm. Septal foramina broad, the length of the siphuncle, ranging from nearly one-half to two-thirds the maximum diameter of the siphuncle. Septal necks cyrtochoanitic, short, recumbent most of the length of the phragmocone. Brims becoming free in adoral portions of the shell, 45-50 mm in diameter. Connecting rings adnate ventrally to both adapical and adoral septa at diameters of 35-40 mm; adnate ventrally to only the adapical septum at diameters greater than 45 mm. Endosiphuncular deposits consisting of small annuli and thin, ventral parietal deposits observed in portions of the phragmocone 15 mm or less in diameter. Cameral deposits consisting of hyposeptal and episeptal deposits occurring at shell diameters of 40 mm or less.

Richmondoceras brevicameratum from the Whitewater Formation of Richmond, Indiana (OUIP 1691)