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Wrevittia hyalodermopse
Original description: Cookson and Eisenack, 1958, p. 34: Gonyaualx hyalodermopsis
Theca thin, transparent and smooth, obtrusely biconical to slightly oval. Epitheca and hypotheca nearly equal. Apex surmounted by a short cylindrical horn with a pointed apex. Transverse girdle shallow, distinctly helicoid, longitudinal furrow broad. Sutures with smooth, thin and shallow ledges. Dorsal plates very large. the tabulation is shown in figs. 5-6. Dimensions: Type - 73 x 55 µm overall, horn 9.
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Plate 11, Figures 5, 9, Plate 24, Figures 1-6
Holotype: Plate 24, Figures 1-4.
Type Locality: Speeton Clay Formation, late Hauterivian, gottschei ammonite Zone. Holotype: Slide top Bed C4C(2), E.F. Q53.4.
Derivation of Name: From the Latin conspicuus, manifest, visible, prominent - in reference to the relatively large size of this subspecies.
Diagnosis: A relatively large, thin-walled subspecies with low, finely granular surface ornament but without prominent intratabular baculae or coni. A prominent, hollow, open-ended apical horn is present, without cornucavation. Tabulation is marked by distally entire crests which are high over much of the cyst, but reduced to low ridges mid-ventrally. A row of small perforations runs along crests adjacent to the archeopyle. Ventral displacement of a prominent cingulum exceeds one cingulum-width and a sulcal claustrum is present. The archeopyle is single-plate precingular (3").
Dimensions: Holotype: Length - 91 μm. Width - 86 μm.
Overall: 101 (89) 78 μm × 86 (77) 68μm.
Specimens Measured: 12.
Remarks: Many of the characteristics of this subspecies are shared with Wrevittia hyalodermopse (Cookson and Eisenack 1958) Duxbury n. comb. subsp. hyalodermopse (autonym) (Plate 24, Figs. 7-11), including the high, distally-entire sutural crests, the low, dense surface ornament and the prominent, hollow apical horn. It is distinguished, however, by its significantly greater size, the possession of regularly perforate crests flanking the archeopyle and in its more “fragile” nature; specimens are typically distorted, precluding detailed analysis of the tabulation.
Occurrences of W. hyalodermopse subsp. conspicua were very largely restricted in the present study to the late Hauterivian and early Barremian, Speeton Beds C4C to LB6, gottschei to variabilis ammonite Zones. However, rare occurrences were also recorded as young as the fissicostatum Zone, Bed LB2D.
Theca thin, transparent and smooth, obtrusely biconical to slightly oval. Epitheca and hypotheca nearly equal. Apex surmounted by a short cylindrical horn with a pointed apex. Transverse girdle shallow, distinctly helicoid, longitudinal furrow broad. Sutures with smooth, thin and shallow ledges. Dorsal plates very large. the tabulation is shown in figs. 5-6. Dimensions: Type - 73 x 55 µm overall, horn 9.
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Plate 11, Figures 5, 9, Plate 24, Figures 1-6
Holotype: Plate 24, Figures 1-4.
Type Locality: Speeton Clay Formation, late Hauterivian, gottschei ammonite Zone. Holotype: Slide top Bed C4C(2), E.F. Q53.4.
Derivation of Name: From the Latin conspicuus, manifest, visible, prominent - in reference to the relatively large size of this subspecies.
Diagnosis: A relatively large, thin-walled subspecies with low, finely granular surface ornament but without prominent intratabular baculae or coni. A prominent, hollow, open-ended apical horn is present, without cornucavation. Tabulation is marked by distally entire crests which are high over much of the cyst, but reduced to low ridges mid-ventrally. A row of small perforations runs along crests adjacent to the archeopyle. Ventral displacement of a prominent cingulum exceeds one cingulum-width and a sulcal claustrum is present. The archeopyle is single-plate precingular (3").
Dimensions: Holotype: Length - 91 μm. Width - 86 μm.
Overall: 101 (89) 78 μm × 86 (77) 68μm.
Specimens Measured: 12.
Remarks: Many of the characteristics of this subspecies are shared with Wrevittia hyalodermopse (Cookson and Eisenack 1958) Duxbury n. comb. subsp. hyalodermopse (autonym) (Plate 24, Figs. 7-11), including the high, distally-entire sutural crests, the low, dense surface ornament and the prominent, hollow apical horn. It is distinguished, however, by its significantly greater size, the possession of regularly perforate crests flanking the archeopyle and in its more “fragile” nature; specimens are typically distorted, precluding detailed analysis of the tabulation.
Occurrences of W. hyalodermopse subsp. conspicua were very largely restricted in the present study to the late Hauterivian and early Barremian, Speeton Beds C4C to LB6, gottschei to variabilis ammonite Zones. However, rare occurrences were also recorded as young as the fissicostatum Zone, Bed LB2D.