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Craspedodinium robustum
From Fensome et al., 2019:
Dolby, 2019, VRp.4–5, pl.1, figs.7–8,12. Holotype: Dolby, 2019, pl.1, fig.7. Age: Aptian - early Albian.
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Original description: [Dolby, 2019]:
Craspedodinium robustum sp. nov.
Plate 1, figures 7-8, 12
Synonymy. Dinocyst OS1, Dolby et al. 2013, pl. 1, fig. 5.
Holotype. Plate 1, figure 7.
Type locality. ConocoPhillips Newby 1AA/03-12-81-6W4, Alberta, 215.55 m, Wabiskaw D Member of the Clearwater Formation.
Repository. National Collection of Type Invertebrate and Plant Fossils, Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario, K1A OE8, under curation number GSC 139222.
Diagnosis. A species of Craspedodinium with a robust periphragm with folds that reflect a gonyaulacacean tabulation.
Description. Shape: The cyst outline is circular, probably circumcavate and randomly orientated. The endophragm is generally folded. The thinner periphragm is variably separated from the endophragm (1-9 μm) and heavily folded.
Tabulation: Gonyaulacacean indicated by distinct pattern of periphragmal folds and archaeopyle sutures (formula: 4', 6" Xc, 6'", 1"", Xs).
Archaeopyle: Apical: operculum usually free.
Cingulum: Indicated by low, parallel folds, 2-4 μm apart.
Epicyst and hypocyst essentially equal.
Surface ornamentation: Endophragm smooth, scabrate or microfoveolate (foveae 1-2 μm in diameter); periphragm smooth to faintly scabrate.
Dimensions [min (mode) max].
Diameter, endophragm: 42 (54) 72 μm, 30 specimens (most specimens in the 52-57 μm range). Holotype: 45 μm.
Diameter, periphragm: 47 (60) 75 μm (most specimens in the 55-65 μm range). Holotype: 49 μm.
Derivation of name. Named for the robust nature of the periphragm.
Discussion. The tabulation is not always obvious, due to the random orientation of the cysts.
Comparison. This species lacks the supports between the endophragm and periphragra evident in Craspedodinium indistinctum from the late Albian. The Jurassic species, Craspedodinium swanense, is larger and dorsoventrally compressed and has an apical boss. In both of those species, the periphragm is significantly more delicate than in Craspedodinium robustum.
Occurrence. Aptian to early Albian, middle and upper McMurray Formation, Clearwater Formation and lower Grand Rapids Formation.
Dolby, 2019, VRp.4–5, pl.1, figs.7–8,12. Holotype: Dolby, 2019, pl.1, fig.7. Age: Aptian - early Albian.
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Original description: [Dolby, 2019]:
Craspedodinium robustum sp. nov.
Plate 1, figures 7-8, 12
Synonymy. Dinocyst OS1, Dolby et al. 2013, pl. 1, fig. 5.
Holotype. Plate 1, figure 7.
Type locality. ConocoPhillips Newby 1AA/03-12-81-6W4, Alberta, 215.55 m, Wabiskaw D Member of the Clearwater Formation.
Repository. National Collection of Type Invertebrate and Plant Fossils, Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario, K1A OE8, under curation number GSC 139222.
Diagnosis. A species of Craspedodinium with a robust periphragm with folds that reflect a gonyaulacacean tabulation.
Description. Shape: The cyst outline is circular, probably circumcavate and randomly orientated. The endophragm is generally folded. The thinner periphragm is variably separated from the endophragm (1-9 μm) and heavily folded.
Tabulation: Gonyaulacacean indicated by distinct pattern of periphragmal folds and archaeopyle sutures (formula: 4', 6" Xc, 6'", 1"", Xs).
Archaeopyle: Apical: operculum usually free.
Cingulum: Indicated by low, parallel folds, 2-4 μm apart.
Epicyst and hypocyst essentially equal.
Surface ornamentation: Endophragm smooth, scabrate or microfoveolate (foveae 1-2 μm in diameter); periphragm smooth to faintly scabrate.
Dimensions [min (mode) max].
Diameter, endophragm: 42 (54) 72 μm, 30 specimens (most specimens in the 52-57 μm range). Holotype: 45 μm.
Diameter, periphragm: 47 (60) 75 μm (most specimens in the 55-65 μm range). Holotype: 49 μm.
Derivation of name. Named for the robust nature of the periphragm.
Discussion. The tabulation is not always obvious, due to the random orientation of the cysts.
Comparison. This species lacks the supports between the endophragm and periphragra evident in Craspedodinium indistinctum from the late Albian. The Jurassic species, Craspedodinium swanense, is larger and dorsoventrally compressed and has an apical boss. In both of those species, the periphragm is significantly more delicate than in Craspedodinium robustum.
Occurrence. Aptian to early Albian, middle and upper McMurray Formation, Clearwater Formation and lower Grand Rapids Formation.