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Isotelus
Classification
Phylum:
Unknown
Class:
Trilobata
Order:
Ptychopariida
Superfamily:
Uncertain
Family:
Asaphidae
Formal Genus Name and Reference:
Isotelus DEKAY, 1824
Type Species:
I. gigas
Images
(Click to enlarge in a new window)
Fig. 251, 2. *I. gigas, 2 a, carapace, x1 (496), 2 b, hypostoma, x0.7 (414n).
Synonyms
Geographic Distribution
North America, Siberia, Northern Europe, Greenland
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:
U.Ord.
Ending International Stage:
Hirnantian
Fraction Up In Ending Stage:
100
Ending Date:
443.07
Description
Cephalon and pygidium mostly with poorly defined flattened border, Frontal area moderately long, cephalic axis ill defined, almost obsolete in several species, slightly expanding in front of medium-size eyes situated somewhat behind transverse mid-line of cranidium, no posterior border furrow, genal angles rounded, pointed, or with short genal spines, Hypostoma almost parallel-sided, posterior margin with broad (tr.), deep notch, anterior lobe short, Thoracic axis considerably broader than pleurae, Pygidial axis broad, poorly defined, almost obsolete in several species, pleural fields smooth or very faintly ribbed
References
Museum or Author Information
Classification
Phylum:
Unknown
Class:
Trilobata
Order:
Ptychopariida
Superfamily:
Uncertain
Family:
Asaphidae
Formal Genus Name and Reference:
Isotelus DEKAY, 1824
Type Species:
I. gigas
Images
(Click to enlarge in a new window)
Fig. 251, 2. *I. gigas, 2 a, carapace, x1 (496), 2 b, hypostoma, x0.7 (414n).
Synonyms
Geographic Distribution
North America, Siberia, Northern Europe, Greenland
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:
U.Ord.
Ending International Stage:
Hirnantian
Fraction Up In Ending Stage:
100
Ending Date:
443.07
Description
Cephalon and pygidium mostly with poorly defined flattened border, Frontal area moderately long, cephalic axis ill defined, almost obsolete in several species, slightly expanding in front of medium-size eyes situated somewhat behind transverse mid-line of cranidium, no posterior border furrow, genal angles rounded, pointed, or with short genal spines, Hypostoma almost parallel-sided, posterior margin with broad (tr.), deep notch, anterior lobe short, Thoracic axis considerably broader than pleurae, Pygidial axis broad, poorly defined, almost obsolete in several species, pleural fields smooth or very faintly ribbed