Spondylus dumosus (Morton, 1834)
MORTON, S. G. 1834. Synopsis of the organic remains of the Cretaceous group of the United States. 88 p. and Appendix, pls. 1-19. W. P. Gibbons, Printer. Key & Biddle, Minor Street. Philadelphia. [p. 59, pl. 16, fig. 8; text-fig.]
1834 Plagiostoma dumosum Morton, 1834
S. G. Morton, 1934, plate 16.
|
«Specific character. Shell obovate, slightly ventricose, with nine or ten slightly elevated ribs, armed with long spines on each valve; spines flattened, and with a longitudinal groove beneath; intervals beneath the ribs, with two or three slightly prominent longitudinal lines.
The annexed cut represents the most perfect specimen, of the natural size: but the largest measures, from beak to base, three inches; from anterior to posterior margins, two inches and a half, and was associated with numbers of nearly the same size in a mass of limestone. Mr. Conrad observed a stratum of this species, in company with OSTREA panda, near low water mark, in the interesting bluff at St. Stephens, on the Tombeckbe; and it is a characteristic species of the newer cretaceous deposits of the southern states.
It has considerable general resemblance to P. spinosum of Sowerby; but differs from the latter in having spines on each valve, those on P. spinosum being confined to the upper valve, as is beautifully illustrated in Cuvier and Brongniart's Geologie des Environs de Paris, pl. iv, fig. 2.» SAMUEL GEORGE MORTON, 1834
|
«Spondylus batequensis n. sp. differs from S. dumosus in the following features: 10-12 rather than 9-10 radial ribs, weaker radial ribs on the left valve, right valve interior with radial ribs throughout, and spinose secondary and tertiary riblets over entire shell exterior rather than only on beak area. These differences become harder to discern on juvenile specimens (less than 30 mm shell height) and juvenile portions of adult specimens of S. dumosus. The evidence suggests that S. batequensis is the ancestral species and some of its morphological traits are retained in the juvenile portion of S. dumosus. Their close relationship is further strengthened by the presence of a longitudinal groove along the bottoms of the flattish radial ribs on both valves.»
SQUIRES, R. L. & R. DEMETRION. 1990. New Eocene marine bivalves from Baja California Sur, Mexico. Journal of Paleontology, 64 (3): 382-391, figs. 1-4.[p. 385]
|
«Discussion: This species is characterized by its flat, rather narrow, elongate spines. The purpose of these long spines was probably to anchor the valves in the muddy sediments of the Red Bluff near-shore, marine shelf environment. Large valves of this species are locally abundant at locality 40, but are rare at most Red Bluff localities in Mississippi.
Type: Holotype missing, from the Red Bluff Formation, Tombigbee River, St. Stephens, Alabama.
Occurrence: Mississippi: Red Bluff Formation, lo calities 34b, 38, 39, 40. Also in the Red Bluff Formation in Alabama.»
DOCKERY III, D. T. 1982. Lower Oligocene bivalvia of the Vicksburg Group in Mississippi. Mississippi Department of Natural Resources, Bureau of Geology, Bulletin, 123: 1-261, pls. 1-62, text-figs. 1-48, appendix of 15 plates. [p. 50]
|
Spondylus (Spondylus) dumosus (Morton); D. T. Dockery III, 1982, Lower Oligocene bivalvia of the Vicksburg Group in Mississippi, plate 14, figures 1-9.
|