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Atrypa
Classification
Phylum:
Brachiopoda
Class:
Rhynchonellata
Order:
Atrypida
Superfamily:
Atrypoidea
Family:
Atrypidae
Formal Genus Name and Reference:
Atrypa DALMAN, 1828, p. 127
Type Species:
Anomia reticularis LINNAEUS, 1758, p. 702, OD
Images
(Click to enlarge in a new window)
Fig. 939 a–d. *A. (A.) reticularis (LINNAEUS), lower Ludlow, Gotland; a–c, dorsal, ventral, posterior views, ×2; d, SEM detail of macroornament, ×12 (new).——FIG. 940 a–d. *A. (A.) reticularis (L INNAEUS), lower Ludlow, Gotland; a–c, serial sections, ×4; d, reconstruction from serial sections, ×3.5 (new).
Synonyms
Geographic Distribution
worldwide
Age Range
Beginning Stage in Treatise Usage:
Silurian (upper Llandovery)
Beginning International Stage:
Telychian
Fraction Up In Beginning Stage:
0
Beginning Date:
438.59
Ending Stage in Treatise Usage:
Middle Devonian (lower Givetian)
Ending International Stage:
Givetian
Fraction Up In Ending Stage:
35
Ending Date:
383.06
Description
medium to large, broadly convexoplane to dorsibiconvex adult shell, ventral valve from very weakly convex apically, dorsal valve usually strongly convex, area generally absent, beak adpressed, foramen transapical or obscured, deltidial plates absent, ribs medium to coarse, regular, concentric, undulose to wavelike growth lamellae, usually expanded as prominent, multiple frills, commissure rectimarginate to plicate, thick pedicle callist, teeth massive, with dental nuclei, accessory lobes (dental cavities in neanic shells), muscle field depressed, vascular ridges weakly to strongly developed around muscle areas, hinge socket plates strong, comblike cardinal process lining cardinal pit, sockets with accessory ridges, crural bases large, bulbous, crura commonly feathered, spiralia dorsal, up to 20 whorls in large shells, jugal processes thick, terminating in long, dorsally directed spatulate jugal plates, differs from ancestral Gotatrypa in convexoplane shell, development of frills, from Atryparia in more imbricate ribs, lack of dental nuclei in adult teeth
References
Museum or Author Information
Classification
Phylum:
Brachiopoda
Class:
Rhynchonellata
Order:
Atrypida
Superfamily:
Atrypoidea
Family:
Atrypidae
Formal Genus Name and Reference:
Atrypa DALMAN, 1828, p. 127
Type Species:
Anomia reticularis LINNAEUS, 1758, p. 702, OD
Images
(Click to enlarge in a new window)
Fig. 939 a–d. *A. (A.) reticularis (LINNAEUS), lower Ludlow, Gotland; a–c, dorsal, ventral, posterior views, ×2; d, SEM detail of macroornament, ×12 (new).——FIG. 940 a–d. *A. (A.) reticularis (L INNAEUS), lower Ludlow, Gotland; a–c, serial sections, ×4; d, reconstruction from serial sections, ×3.5 (new).
Synonyms
Geographic Distribution
worldwide
Age Range
Beginning Stage in Treatise Usage:
Silurian (upper Llandovery)
Beginning International Stage:
Telychian
Fraction Up In Beginning Stage:
0
Beginning Date:
438.59
Ending Stage in Treatise Usage:
Middle Devonian (lower Givetian)
Ending International Stage:
Givetian
Fraction Up In Ending Stage:
35
Ending Date:
383.06
Description
medium to large, broadly convexoplane to dorsibiconvex adult shell, ventral valve from very weakly convex apically, dorsal valve usually strongly convex, area generally absent, beak adpressed, foramen transapical or obscured, deltidial plates absent, ribs medium to coarse, regular, concentric, undulose to wavelike growth lamellae, usually expanded as prominent, multiple frills, commissure rectimarginate to plicate, thick pedicle callist, teeth massive, with dental nuclei, accessory lobes (dental cavities in neanic shells), muscle field depressed, vascular ridges weakly to strongly developed around muscle areas, hinge socket plates strong, comblike cardinal process lining cardinal pit, sockets with accessory ridges, crural bases large, bulbous, crura commonly feathered, spiralia dorsal, up to 20 whorls in large shells, jugal processes thick, terminating in long, dorsally directed spatulate jugal plates, differs from ancestral Gotatrypa in convexoplane shell, development of frills, from Atryparia in more imbricate ribs, lack of dental nuclei in adult teeth