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Dawsonoceras
Classification
Phylum:
Mollusca
Class:
Cephalopoda
Subclass:
Nautiloidea
Order:
Orthocerida
Superfamily:
Orthocerataceae
Family:
Dawsonoceratidae
Formal Genus Name and Reference:
Dawsonoceras HYATT, 1884, p. 276
Type Species:
Orthocera annulata SOWERBY, 1818, p. 77, OD
Images
(Click to enlarge in a new window)
Fig. 170, 1b,c. *D. annulatum (Sowerby), M.Sil., Eng. (Shrops.), detail of shell surf. (enlarged), lat. view, x0.4 (61). -- Fig. 170, 1a. D. sp., diagram of shell interior, enlarged (22).
Synonyms
Cedarvilleoceras
Geographic Distribution
Eu. (Est.), L. Sil.-U.Sil., N.Am.-Eu.-Asia-Australia, ?M.Dev., Can. (Ont.)
Age Range
Beginning Stage in Treatise Usage:
U.Ord., L. Sil.
Beginning International Stage:
Sandbian
Fraction Up In Beginning Stage:
0
Beginning Date:
458.18
Ending Stage in Treatise Usage:
U.Sil., ?M.Dev.
Ending International Stage:
Givetian
Fraction Up In Ending Stage:
100
Ending Date:
378.9
Description
Straight to slightly curved orthocones with circular to subcircular transverse section, straight transverse sutures and shell with conspicuous transverse annulations. Surface markings consist typically of scalloped or festooned transverse lirae but may include secondary longitudinal lirae. Siphuncle subcentral, septal necks short, recumbent, segments occupied by small annulosiphonate deposits. Camerae with mural deposits.
References
Museum or Author Information
Classification
Phylum:
Mollusca
Class:
Cephalopoda
Subclass:
Nautiloidea
Order:
Orthocerida
Superfamily:
Orthocerataceae
Family:
Dawsonoceratidae
Formal Genus Name and Reference:
Dawsonoceras HYATT, 1884, p. 276
Type Species:
Orthocera annulata SOWERBY, 1818, p. 77, OD
Images
(Click to enlarge in a new window)
Fig. 170, 1b,c. *D. annulatum (Sowerby), M.Sil., Eng. (Shrops.), detail of shell surf. (enlarged), lat. view, x0.4 (61). -- Fig. 170, 1a. D. sp., diagram of shell interior, enlarged (22).
Synonyms
Cedarvilleoceras
Geographic Distribution
Eu. (Est.), L. Sil.-U.Sil., N.Am.-Eu.-Asia-Australia, ?M.Dev., Can. (Ont.)
Age Range
Beginning Stage in Treatise Usage:
U.Ord., L. Sil.
Beginning International Stage:
Sandbian
Fraction Up In Beginning Stage:
0
Beginning Date:
458.18
Ending Stage in Treatise Usage:
U.Sil., ?M.Dev.
Ending International Stage:
Givetian
Fraction Up In Ending Stage:
100
Ending Date:
378.9
Description
Straight to slightly curved orthocones with circular to subcircular transverse section, straight transverse sutures and shell with conspicuous transverse annulations. Surface markings consist typically of scalloped or festooned transverse lirae but may include secondary longitudinal lirae. Siphuncle subcentral, septal necks short, recumbent, segments occupied by small annulosiphonate deposits. Camerae with mural deposits.