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Nanorthis
Classification
Phylum:
Brachiopoda
Subphylum:
Rhynchonelliformea
Class:
Rhynchonellata
Order:
Orthida
Suborder:
Orthidina
Superfamily:
Plectorthoidea
Family:
Plectorthidae
Formal Genus Name and Reference:
Nanorthis Ulrich & COOPER, 1936, p. 621
Type Species:
Orthis hamburgensis WALCOTT, 1884, p. 73, OD
Images
(Click to enlarge in a new window)
Fig. 1791, 2a-h, N. hamburgensis (Walcott), western USA, a, dorsal exterior, ×4.5, b, ventral exterior, ×4.5, c, dorsal interior, ×6, d, ventral interior, ×6 (Ulrich & Cooper, 1938), e-f, topotypes, ventral exterior with detail showing siliceous nodules on costellae, interpreted as aditicules, ×12, ×35, g-h, topotypes, ventral and tilted views of dorsal cardinalia, ×27, ×24 (new).
Synonyms
Evenkinorthis
Geographic Distribution
cosmopolitan
Age Range
Beginning Stage in Treatise Usage:
Lower Ordovician (Tremadoc)
Beginning International Stage:
Tremadocian
Fraction Up In Beginning Stage:
0
Beginning Date:
486.85
Ending Stage in Treatise Usage:
Lower Ordovician (Tremadoc)
Ending International Stage:
Tremadocian
Fraction Up In Ending Stage:
100
Ending Date:
477.08
Description
Subcircular with obtuse cardinal extremities, ramicostellae with sharp crests, apparently indented by aditicules; short, bladelike brachiophores with convergent supporting plates and fulcral plates, notothyrial platform rudimentary, lacking cardinal process. [Evenkinorthis has been erected for inadequately described and illustrated specimens from the Lower Ordovician of Siberia. With regard to such features as are unambiguously determinable, the genus is indistinguishable from Nanorthis. The reasons for amending the diagnosis of Nanorthis and transferring the genus from the Orthoidea (see Williams & Harper, 2000, p. 742) to the Plectorthoidea are given herein, p. 2684–2687.]
References
Museum or Author Information
Classification
Phylum:
Brachiopoda
Subphylum:
Rhynchonelliformea
Class:
Rhynchonellata
Order:
Orthida
Suborder:
Orthidina
Superfamily:
Plectorthoidea
Family:
Plectorthidae
Formal Genus Name and Reference:
Nanorthis Ulrich & COOPER, 1936, p. 621
Type Species:
Orthis hamburgensis WALCOTT, 1884, p. 73, OD
Images
(Click to enlarge in a new window)
Fig. 1791, 2a-h, N. hamburgensis (Walcott), western USA, a, dorsal exterior, ×4.5, b, ventral exterior, ×4.5, c, dorsal interior, ×6, d, ventral interior, ×6 (Ulrich & Cooper, 1938), e-f, topotypes, ventral exterior with detail showing siliceous nodules on costellae, interpreted as aditicules, ×12, ×35, g-h, topotypes, ventral and tilted views of dorsal cardinalia, ×27, ×24 (new).
Synonyms
Evenkinorthis
Geographic Distribution
cosmopolitan
Age Range
Beginning Stage in Treatise Usage:
Lower Ordovician (Tremadoc)
Beginning International Stage:
Tremadocian
Fraction Up In Beginning Stage:
0
Beginning Date:
486.85
Ending Stage in Treatise Usage:
Lower Ordovician (Tremadoc)
Ending International Stage:
Tremadocian
Fraction Up In Ending Stage:
100
Ending Date:
477.08
Description
Subcircular with obtuse cardinal extremities, ramicostellae with sharp crests, apparently indented by aditicules; short, bladelike brachiophores with convergent supporting plates and fulcral plates, notothyrial platform rudimentary, lacking cardinal process. [Evenkinorthis has been erected for inadequately described and illustrated specimens from the Lower Ordovician of Siberia. With regard to such features as are unambiguously determinable, the genus is indistinguishable from Nanorthis. The reasons for amending the diagnosis of Nanorthis and transferring the genus from the Orthoidea (see Williams & Harper, 2000, p. 742) to the Plectorthoidea are given herein, p. 2684–2687.]