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Orbiculoidea
Classification
Phylum:
Brachiopoda
Class:
Lingulata
Order:
Lingulida
Superfamily:
Discinoidea
Family:
Discinidae
Formal Genus Name and Reference:
Orbiculoidea D'ORBIGNY, 1847, p. 269
Type Species:
Orbicula forbesii Davidson, 1848, p. 334, ICZN opinion 722, 1965b
Images
(Click to enlarge in a new window)
Fig. 43, 2a-c. *O. ?forbesii (Davidson), Wenlock, England, ventral valve exterior, dorsal valve exterior, lateral view of both valves, $X_{4}$ (Rowell, 1965a).
Synonyms
Geographic Distribution
cosmopolitan (exact stratigraphic and geographic range is very uncertain)
Age Range
Beginning Stage in Treatise Usage:
Ordovician, Silurian
Beginning International Stage:
Tremadocian
Fraction Up In Beginning Stage:
0
Beginning Date:
486.85
Ending Stage in Treatise Usage:
Permian
Ending International Stage:
Changhsingian
Fraction Up In Ending Stage:
100
Ending Date:
251.9
Description
Shell strongly dorsibiconvex to convexoplane, subcircular, ornament of both valves usually with well-developed, concentric fila, dorsal valve conical to subconical, apex variably positioned, ventral valve low subconical to gently concave, pedicle track narrow, closed anteriorly by listrium, foramen at posterior end of listrium, continued as internal tube to open in front of posterior margin.
References
Museum or Author Information
Classification
Phylum:
Brachiopoda
Class:
Lingulata
Order:
Lingulida
Superfamily:
Discinoidea
Family:
Discinidae
Formal Genus Name and Reference:
Orbiculoidea D'ORBIGNY, 1847, p. 269
Type Species:
Orbicula forbesii Davidson, 1848, p. 334, ICZN opinion 722, 1965b
Images
(Click to enlarge in a new window)
Fig. 43, 2a-c. *O. ?forbesii (Davidson), Wenlock, England, ventral valve exterior, dorsal valve exterior, lateral view of both valves, $X_{4}$ (Rowell, 1965a).
Synonyms
Geographic Distribution
cosmopolitan (exact stratigraphic and geographic range is very uncertain)
Age Range
Beginning Stage in Treatise Usage:
Ordovician, Silurian
Beginning International Stage:
Tremadocian
Fraction Up In Beginning Stage:
0
Beginning Date:
486.85
Ending Stage in Treatise Usage:
Permian
Ending International Stage:
Changhsingian
Fraction Up In Ending Stage:
100
Ending Date:
251.9
Description
Shell strongly dorsibiconvex to convexoplane, subcircular, ornament of both valves usually with well-developed, concentric fila, dorsal valve conical to subconical, apex variably positioned, ventral valve low subconical to gently concave, pedicle track narrow, closed anteriorly by listrium, foramen at posterior end of listrium, continued as internal tube to open in front of posterior margin.