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Gryphaeostrea
Classification
Phylum:
Mollusca
Class:
None
Subclass:
Pteriomorphia
Order:
Pterioida
Suborder:
Ostreina (oysters)
Superfamily:
Ostreacea
Family:
Gryphaeidae
Subfamily:
Exogyrinae - TRIBE Gryphaeostreni
Formal Genus Name and Reference:
Gryphaeostrea CONRAD, 15 April 1865a, unnumbered errata page following p. 190, nom. correct.
Type Species:
Cryphaea eversa MELLEvILLE, 1843, p. 87; M
Images
(Click to enlarge in a new window)
Fig. J98,1. *C. eversa (MELLEVILLE), 10w.Eoc. (Thanet.), France (Paris Basin); la-f, LV int., ext., another specimen LV ext., other specimens RV int., ext., RV ext., all X2 (photographs courtesy of N. J. MORRIS, British Museum, Natural History). -- Fig. J98,2. C. sp. (=C. vomer STEPHENSON, 1941, non MORTON, 1828), U.Cret. (Maastricht., Corsicana Marl), Texas(Bowie Co.); 2a-e, LV ext., int., RV ext., int., ext., all X I (Stephenson, 1941). - -Fig. J98,3. C. plicatella (MORTON, 1833), up.Eoc. (Jackson), Miss. (Shubuta); 3a-f, LV ext., int., int., RV ext. (3 specimens), all X I (Harris, 1946).
Synonyms
Gryphoeostrea, Gryphostrea
Geographic Distribution
L.Cret. (t/p.Apt.) -Mio.(Torton.) , Eu.(Eng.-France-Neth.-Belg.-Ger.-Denm.-Sweden-Switz.-Spain-Italy- Aus.-Bulg.-USSR) - Afr. (Moroc.-Alg.-Tunisia-Libya-Egypt-Congo-Somali!. -Madag.); L. Cret. (Alb.)Oligo. (Rupel.) , N.Am.(N.J. to Mexico
Age Range
Beginning Stage in Treatise Usage:
L.Cret. (up.Apt.)
Beginning International Stage:
Aptian
Fraction Up In Beginning Stage:
66
Beginning Date:
115.99
Ending Stage in Treatise Usage:
Mio.(Torton.)
Ending International Stage:
Tortonian
Fraction Up In Ending Stage:
100
Ending Date:
7.25
Description
Small (less than 3.5 em.) although some species reach 3.9 by 6.5 em. size. LV highly convex and capacious, its commissural shelf well developed but without any chomata; deep umbonal cavity overhung by hinge plate; attachment area large in many species, small in some, restricted in position to posterior or posterodorsal flank of valve and inclined at 45 0 to 900 roughly to anteroposterior direction. LV beak opisthogyrally spiral; anterior wall of LV spirally curved and rising up obliquely or vertically from substratum; LV smooth, lacking radial ribs or folds except in few last surviving species; smooth growth lines give way to squamae in last stages of growth; angular to spoonshaped shelly claspers grow out periodically from growth squamae of LV to provide additional attachments. RV flat; outline oval to spatulate or triangular, devoid of claspers and chomata; its umbo flat, growth squamae simple, smooth, devoid of frills, folds, ribs, or plicae, and spaced regularly apart starting close to umbo. RV considerably smaller than LV, leaving wide (up to 0.7 em.) margin on LV uncovered in bivalved fossil specimens. On both valves ligamental area is deep narrow spiral groove which abruptly widens and straightens out near end of individual growth. [STENZEL (1947. p. 175) found that the type species was originally designated through monotypy. Many authors have classed the genus among the exogyras (see COSSMANN & PEWOT. 1914, p. 197; JOURDV, 1924, p. 31. 96-97, pI. 4. fig. 2; GLIBERT & VAN DE POEL, 1965. p. 56), whereas STENZEL (1959. p. 31) had argued that it must be excluded from the Exogyrinae. This opinion is no longer maintained. Gryphaeostrea is easily recognized as a genus, because of the configuration of the ligamentaI area and the regularly spaced concentric RV squamae. Only the tribe Flemingostreini has similar concentric RV squamae. Gryphaeostrea is the only genus of the Exogyrinae to survive the end of the Cretaceous Period. The last surviving species were G. ricardi (COSSMANN & PEYROT, 1914, p. 197, pI. 20. fig. 29-36) from the early Burdigal. of Saueats, Departement Gironde. south of Bordeaux. France, and G. miotaurinensis (SACCO, 1897, p. 30, pI. 9, fig. 15-33) from the Helvetian of the Colli di Torino, northern Italy, which is reported by AZZAROLI (1958, p. 1l0, pI. 27, fig. 7ยท9) as widespread in the Miocene (Burdigal. to Tonon.) of Somalia, Cirenaica, and Venetia. In North America the last species. as yet undescribed, are found in the Cooper Marl (Ludian) and Marianna limestone (Rupelian) of South Carolina and Mississippi according to F. STEARNS MACNEIL (personal communication). These last species have radial ribs on the left valve.]
References
Museum or Author Information
Classification
Phylum:
Mollusca
Class:
None
Subclass:
Pteriomorphia
Order:
Pterioida
Suborder:
Ostreina (oysters)
Superfamily:
Ostreacea
Family:
Gryphaeidae
Subfamily:
Exogyrinae - TRIBE Gryphaeostreni
Formal Genus Name and Reference:
Gryphaeostrea CONRAD, 15 April 1865a, unnumbered errata page following p. 190, nom. correct.
Type Species:
Cryphaea eversa MELLEvILLE, 1843, p. 87; M
Images
(Click to enlarge in a new window)
Fig. J98,1. *C. eversa (MELLEVILLE), 10w.Eoc. (Thanet.), France (Paris Basin); la-f, LV int., ext., another specimen LV ext., other specimens RV int., ext., RV ext., all X2 (photographs courtesy of N. J. MORRIS, British Museum, Natural History). -- Fig. J98,2. C. sp. (=C. vomer STEPHENSON, 1941, non MORTON, 1828), U.Cret. (Maastricht., Corsicana Marl), Texas(Bowie Co.); 2a-e, LV ext., int., RV ext., int., ext., all X I (Stephenson, 1941). - -Fig. J98,3. C. plicatella (MORTON, 1833), up.Eoc. (Jackson), Miss. (Shubuta); 3a-f, LV ext., int., int., RV ext. (3 specimens), all X I (Harris, 1946).
Synonyms
Gryphoeostrea, Gryphostrea
Geographic Distribution
L.Cret. (t/p.Apt.) -Mio.(Torton.) , Eu.(Eng.-France-Neth.-Belg.-Ger.-Denm.-Sweden-Switz.-Spain-Italy- Aus.-Bulg.-USSR) - Afr. (Moroc.-Alg.-Tunisia-Libya-Egypt-Congo-Somali!. -Madag.); L. Cret. (Alb.)Oligo. (Rupel.) , N.Am.(N.J. to Mexico
Age Range
Beginning Stage in Treatise Usage:
L.Cret. (up.Apt.)
Beginning International Stage:
Aptian
Fraction Up In Beginning Stage:
66
Beginning Date:
115.99
Ending Stage in Treatise Usage:
Mio.(Torton.)
Ending International Stage:
Tortonian
Fraction Up In Ending Stage:
100
Ending Date:
7.25
Description
Small (less than 3.5 em.) although some species reach 3.9 by 6.5 em. size. LV highly convex and capacious, its commissural shelf well developed but without any chomata; deep umbonal cavity overhung by hinge plate; attachment area large in many species, small in some, restricted in position to posterior or posterodorsal flank of valve and inclined at 45 0 to 900 roughly to anteroposterior direction. LV beak opisthogyrally spiral; anterior wall of LV spirally curved and rising up obliquely or vertically from substratum; LV smooth, lacking radial ribs or folds except in few last surviving species; smooth growth lines give way to squamae in last stages of growth; angular to spoonshaped shelly claspers grow out periodically from growth squamae of LV to provide additional attachments. RV flat; outline oval to spatulate or triangular, devoid of claspers and chomata; its umbo flat, growth squamae simple, smooth, devoid of frills, folds, ribs, or plicae, and spaced regularly apart starting close to umbo. RV considerably smaller than LV, leaving wide (up to 0.7 em.) margin on LV uncovered in bivalved fossil specimens. On both valves ligamental area is deep narrow spiral groove which abruptly widens and straightens out near end of individual growth. [STENZEL (1947. p. 175) found that the type species was originally designated through monotypy. Many authors have classed the genus among the exogyras (see COSSMANN & PEWOT. 1914, p. 197; JOURDV, 1924, p. 31. 96-97, pI. 4. fig. 2; GLIBERT & VAN DE POEL, 1965. p. 56), whereas STENZEL (1959. p. 31) had argued that it must be excluded from the Exogyrinae. This opinion is no longer maintained. Gryphaeostrea is easily recognized as a genus, because of the configuration of the ligamentaI area and the regularly spaced concentric RV squamae. Only the tribe Flemingostreini has similar concentric RV squamae. Gryphaeostrea is the only genus of the Exogyrinae to survive the end of the Cretaceous Period. The last surviving species were G. ricardi (COSSMANN & PEYROT, 1914, p. 197, pI. 20. fig. 29-36) from the early Burdigal. of Saueats, Departement Gironde. south of Bordeaux. France, and G. miotaurinensis (SACCO, 1897, p. 30, pI. 9, fig. 15-33) from the Helvetian of the Colli di Torino, northern Italy, which is reported by AZZAROLI (1958, p. 1l0, pI. 27, fig. 7ยท9) as widespread in the Miocene (Burdigal. to Tonon.) of Somalia, Cirenaica, and Venetia. In North America the last species. as yet undescribed, are found in the Cooper Marl (Ludian) and Marianna limestone (Rupelian) of South Carolina and Mississippi according to F. STEARNS MACNEIL (personal communication). These last species have radial ribs on the left valve.]