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Alaskospira
Classification
Phylum:
Brachiopoda
Subphylum:
Rhynchonelliformea
Class:
Rhynchonellata
Order:
Spiriferida
Suborder:
Delthyridina
Superfamily:
Reticularioidea
Family:
Reticulariidae
Subfamily:
Obesariinae
Formal Genus Name and Reference:
Alaskospira Kirk & Amsden, 1952, p. 61
Type Species:
A. dunbari, OD
Images
(Click to enlarge in a new window)
Fig. 1236, 2a-i. *A. dunbari, upper Wenlock, Alaska, USA, a-d, dorsal, ventral, posterior, lateral views, X2, e, ornament, X6, f-i, serial sections, X1.5 (Kirk & Amsden, 1952).
Synonyms
Proreticularia
Geographic Distribution
USA (Alaska), Czech Republic, Urals, Australia (New South Wales)
Age Range
Beginning Stage in Treatise Usage:
Silurian (upper Wenlock)
Beginning International Stage:
Homerian
Fraction Up In Beginning Stage:
50
Beginning Date:
428.68
Ending Stage in Treatise Usage:
Lower Devonian (Emsian)
Ending International Stage:
Emsian
Fraction Up In Ending Stage:
100
Ending Date:
394.3
Description
Medium size, equidimensional to slightly transverse, with apsacline, curved ventral interarea, cardinal angles rounded, fold and sulcus ill defined except near anterior commissure, shell surface smooth, microornament of closely spaced growth lines and radial rows of spines, dental plates lacking, strong apical thickening, muscle field deeply impressed, divided by a median ridge extending nearly to anterior margin, ctenophoridium and crural plates lacking, low myophragm.
References
Museum or Author Information
Classification
Phylum:
Brachiopoda
Subphylum:
Rhynchonelliformea
Class:
Rhynchonellata
Order:
Spiriferida
Suborder:
Delthyridina
Superfamily:
Reticularioidea
Family:
Reticulariidae
Subfamily:
Obesariinae
Formal Genus Name and Reference:
Alaskospira Kirk & Amsden, 1952, p. 61
Type Species:
A. dunbari, OD
Images
(Click to enlarge in a new window)
Fig. 1236, 2a-i. *A. dunbari, upper Wenlock, Alaska, USA, a-d, dorsal, ventral, posterior, lateral views, X2, e, ornament, X6, f-i, serial sections, X1.5 (Kirk & Amsden, 1952).
Synonyms
Proreticularia
Geographic Distribution
USA (Alaska), Czech Republic, Urals, Australia (New South Wales)
Age Range
Beginning Stage in Treatise Usage:
Silurian (upper Wenlock)
Beginning International Stage:
Homerian
Fraction Up In Beginning Stage:
50
Beginning Date:
428.68
Ending Stage in Treatise Usage:
Lower Devonian (Emsian)
Ending International Stage:
Emsian
Fraction Up In Ending Stage:
100
Ending Date:
394.3
Description
Medium size, equidimensional to slightly transverse, with apsacline, curved ventral interarea, cardinal angles rounded, fold and sulcus ill defined except near anterior commissure, shell surface smooth, microornament of closely spaced growth lines and radial rows of spines, dental plates lacking, strong apical thickening, muscle field deeply impressed, divided by a median ridge extending nearly to anterior margin, ctenophoridium and crural plates lacking, low myophragm.