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Geisonoceras
Classification
Phylum:
Mollusca
Class:
Cephalopoda
Subclass:
Nautiloidea
Order:
Orthocerida
Superfamily:
Orthocerataceae
Family:
Geisonoceratidae
Formal Genus Name and Reference:
Geisonoceras HYATT, 1884, p. 275
Type Species:
OrtIlOceras rit/ale BARRANDE, 1866, pI. 209; 00
Images
(Click to enlarge in a new window)
Fig. 169, 6. *G. rivale (BARRANDE), M.Sil., Eu.(Czech.); 6a,b, lat. view, dorsoventral sec., X0.5 (5)
Synonyms
Geographic Distribution
N.Am.-Eu.-Asia
Age Range
Beginning Stage in Treatise Usage:
M.Ord.
Beginning International Stage:
Dapingian
Fraction Up In Beginning Stage:
0
Beginning Date:
471.26
Ending Stage in Treatise Usage:
M.Dev.
Ending International Stage:
Givetian
Fraction Up In Ending Stage:
100
Ending Date:
378.9
Description
Slowly enlarging orthocones or cyrtocones of circular to subcircular cross section and with straight transverse or slightly oblique sutures. Siphuncle sub-central; necks short and straight, connecting rings expanding slightly within camerae. Small adorally attenuated annulosiphonate deposits in adapical siphuncular segments; camerae with episeptal and hyposeptal deposits. Surface with broad transverse bands, between which are fine growth lines. Aperture transverse, with slight hyponomic sinus.
References
Museum or Author Information
Classification
Phylum:
Mollusca
Class:
Cephalopoda
Subclass:
Nautiloidea
Order:
Orthocerida
Superfamily:
Orthocerataceae
Family:
Geisonoceratidae
Formal Genus Name and Reference:
Geisonoceras HYATT, 1884, p. 275
Type Species:
OrtIlOceras rit/ale BARRANDE, 1866, pI. 209; 00
Images
(Click to enlarge in a new window)
Fig. 169, 6. *G. rivale (BARRANDE), M.Sil., Eu.(Czech.); 6a,b, lat. view, dorsoventral sec., X0.5 (5)
Synonyms
Geographic Distribution
N.Am.-Eu.-Asia
Age Range
Beginning Stage in Treatise Usage:
M.Ord.
Beginning International Stage:
Dapingian
Fraction Up In Beginning Stage:
0
Beginning Date:
471.26
Ending Stage in Treatise Usage:
M.Dev.
Ending International Stage:
Givetian
Fraction Up In Ending Stage:
100
Ending Date:
378.9
Description
Slowly enlarging orthocones or cyrtocones of circular to subcircular cross section and with straight transverse or slightly oblique sutures. Siphuncle sub-central; necks short and straight, connecting rings expanding slightly within camerae. Small adorally attenuated annulosiphonate deposits in adapical siphuncular segments; camerae with episeptal and hyposeptal deposits. Surface with broad transverse bands, between which are fine growth lines. Aperture transverse, with slight hyponomic sinus.