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Geragnostus
Classification
Phylum:
Unknown
Class:
Trilobata
Order:
Agnostida
Superfamily:
Agnostoidea
Family:
Metagnostidae
Formal Genus Name and Reference:
Geragnostus HOWELL, 1935b, p. 231
Type Species:
Agnostus sidenbladhi Linnarsson, 1869, p. 82, OD, lectotype (Linnarsson, 1869, pl. 2, fig. 61, SD AHLBERG, 1989, p. 310), 25, SGU, Uppsala
Images
(Click to enlarge in a new window)
Fig. 237,4a,b. *G. sidenbladhi (Linnarsson), Lower Ordovician (upper Tremadoc, Apatokephalus serratus Biozone), a, Sweden (Hunneberg, Västergötland), cephalon, SGU 7886, X12 (Ahlberg, 1989, fig. 1a,b), b, Sweden (Mossebo, Hunneberg, Västergötland), lectotype, pygidium, SGU 25, X1 1 (Ahlberg, 1989, fig. 3a)."
Synonyms
Geratrinodus Kobayashi & Hamada, 1978, p. 8 (type, G. perconvexus, OD), Neptunagnostella Рек, 1977, p. 14 (type, Agnostus consors Holub, 1912, p. 6, pl. 1, fig. 5)
Geographic Distribution
Sweden, upper Tremadoc–Llanvirn; Norway, upper Tremadoc; France, upper Tremadoc–lower Arenig; Czech Republic, Arenig–Llanvirn; Scotland, Llandeilo; England, upper Tremadoc; Canada (Newfoundland), Whiterock; Argentina, Tremadoc; Turkey, Arenig; Tadzhikistan, Arenig; Uzbekistan, Ashgill; China (Hubei, Hunan), TremadocLlanvirn; USA (Nevada), ? Lower Ordovician; Malaysia, ?middle Ordovician.
Age Range
Beginning Stage in Treatise Usage:
Ordovician
Beginning International Stage:
Tremadocian
Fraction Up In Beginning Stage:
0
Beginning Date:
486.85
Ending Stage in Treatise Usage:
Ordovician
Ending International Stage:
Hirnantian
Fraction Up In Ending Stage:
0
Ending Date:
443.07
Description
En grande tenue to nearly entirely effaced, Glabella with semiovate anterior lobe, F3 effaced or with straight median portion, lateral portions curving forward and outward, posterior lobe with weak F2 furrows, glabellar node immediately behind F3 furrow, Pygidial axis of moderate length, commonly constricted across M2, posterior lobe nearly equidimensional, semiovate to subrectangular, commonly with weak terminal node.
References
Museum or Author Information
Classification
Phylum:
Unknown
Class:
Trilobata
Order:
Agnostida
Superfamily:
Agnostoidea
Family:
Metagnostidae
Formal Genus Name and Reference:
Geragnostus HOWELL, 1935b, p. 231
Type Species:
Agnostus sidenbladhi Linnarsson, 1869, p. 82, OD, lectotype (Linnarsson, 1869, pl. 2, fig. 61, SD AHLBERG, 1989, p. 310), 25, SGU, Uppsala
Images
(Click to enlarge in a new window)
Fig. 237,4a,b. *G. sidenbladhi (Linnarsson), Lower Ordovician (upper Tremadoc, Apatokephalus serratus Biozone), a, Sweden (Hunneberg, Västergötland), cephalon, SGU 7886, X12 (Ahlberg, 1989, fig. 1a,b), b, Sweden (Mossebo, Hunneberg, Västergötland), lectotype, pygidium, SGU 25, X1 1 (Ahlberg, 1989, fig. 3a)."
Synonyms
Geratrinodus Kobayashi & Hamada, 1978, p. 8 (type, G. perconvexus, OD), Neptunagnostella Рек, 1977, p. 14 (type, Agnostus consors Holub, 1912, p. 6, pl. 1, fig. 5)
Geographic Distribution
Sweden, upper Tremadoc–Llanvirn; Norway, upper Tremadoc; France, upper Tremadoc–lower Arenig; Czech Republic, Arenig–Llanvirn; Scotland, Llandeilo; England, upper Tremadoc; Canada (Newfoundland), Whiterock; Argentina, Tremadoc; Turkey, Arenig; Tadzhikistan, Arenig; Uzbekistan, Ashgill; China (Hubei, Hunan), TremadocLlanvirn; USA (Nevada), ? Lower Ordovician; Malaysia, ?middle Ordovician.
Age Range
Beginning Stage in Treatise Usage:
Ordovician
Beginning International Stage:
Tremadocian
Fraction Up In Beginning Stage:
0
Beginning Date:
486.85
Ending Stage in Treatise Usage:
Ordovician
Ending International Stage:
Hirnantian
Fraction Up In Ending Stage:
0
Ending Date:
443.07
Description
En grande tenue to nearly entirely effaced, Glabella with semiovate anterior lobe, F3 effaced or with straight median portion, lateral portions curving forward and outward, posterior lobe with weak F2 furrows, glabellar node immediately behind F3 furrow, Pygidial axis of moderate length, commonly constricted across M2, posterior lobe nearly equidimensional, semiovate to subrectangular, commonly with weak terminal node.