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Scriniodinium eliminatum
From Fensome et al., 2019:
Scriniodinium elimatum Duxbury, 2018, p.192–193, pl.4, figs.1–8. Holotype: Duxbury, 2018, pl.4, figs.1–3. Age: early Valanginian.
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Original description Duxbury, 2018:
Plate 4, figures 1–8, text-figure 8
Scriniodinium dictyotum Cookson and Eisenack 1960 – HABIB 1974, pl. 1, figs. 3, 4, pl. 2, fig. 1, text-figure 2, c, d.
Holotype: Plate 4, Figures 1–3
Paratype: Plate 4, Figures 5, 6
Type Locality: Well 20/01-8 at 6893.70 ft (conventional core chip), lower Valanginian. Holotype: E.F. T44.0. Paratype: E.F. L28.0
Derivation of Name: From the Latin elimatus, finished, elaborated, adorned – in reference to the ornament of this species.
Diagnosis: A large, robust species often displaying a complete tabulation with the formula 1a.cl., 1a.a., 4', 6", 6c, 5"', 1"". Characteristic reticulation is variably developed, sometimes limited to the crestal ridges, where it has as a regular alveolate appearance but in more ornate specimens it can form a low network over the cyst surface. Thicker-walled morphotypes tend to be more ornate. The dorso-ventral cyst outline is ovoid with an obliquely flattened antapex and an endocystal apical protrusion, and a short pericystal apical horn is invariably present. The
archeopyle is single plate precingular (3").
Dimensions: Holotype: 91 × 78 μm.
Overall: 114 (98) 84 μm × 99 (82) 73μm.
Specimens Measured: 16.
Remarks: Scriniodinium elimatum n. sp. was described as Scriniodinium dictyotum Cookson and Eisenack 1960 by Habib (1974), who implied that there was a gradation from S. dictyotum to Scriniodinium campanula Gocht 1959 within the Berriasian to Valanginian interval of the western North Atlantic. There is some similarity between the less–ornamented specimens of Scriniodinium elimatum n. sp. and Scriniodinium campanula, which supports Habib’s (1974) suggestion of a relationship. However, although Scriniodinium campanula is recorded as old as the Berriasian, Scriniodinium elimatum n. sp. appears to be restricted to the Valanginian and early Hauterivian, suggesting that the latter derived from the former, rather than the other way round, as suggested by Habib (op. cit.). In the UKCS Central North Sea, the highest occurrence of true S. dictyotum is within the mid Kimmeridgian (Duxbury et al. 1999). Riding and Fensome (2003, p. 16) appear to have accepted Habib’s specimens as true S. dictyotum, although their range chart (text-fig. 2) has a similar range top for S. dictyotum to that in Duxbury et al. (op cit.).
Scriniodinium elimatum Duxbury, 2018, p.192–193, pl.4, figs.1–8. Holotype: Duxbury, 2018, pl.4, figs.1–3. Age: early Valanginian.
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Original description Duxbury, 2018:
Plate 4, figures 1–8, text-figure 8
Scriniodinium dictyotum Cookson and Eisenack 1960 – HABIB 1974, pl. 1, figs. 3, 4, pl. 2, fig. 1, text-figure 2, c, d.
Holotype: Plate 4, Figures 1–3
Paratype: Plate 4, Figures 5, 6
Type Locality: Well 20/01-8 at 6893.70 ft (conventional core chip), lower Valanginian. Holotype: E.F. T44.0. Paratype: E.F. L28.0
Derivation of Name: From the Latin elimatus, finished, elaborated, adorned – in reference to the ornament of this species.
Diagnosis: A large, robust species often displaying a complete tabulation with the formula 1a.cl., 1a.a., 4', 6", 6c, 5"', 1"". Characteristic reticulation is variably developed, sometimes limited to the crestal ridges, where it has as a regular alveolate appearance but in more ornate specimens it can form a low network over the cyst surface. Thicker-walled morphotypes tend to be more ornate. The dorso-ventral cyst outline is ovoid with an obliquely flattened antapex and an endocystal apical protrusion, and a short pericystal apical horn is invariably present. The
archeopyle is single plate precingular (3").
Dimensions: Holotype: 91 × 78 μm.
Overall: 114 (98) 84 μm × 99 (82) 73μm.
Specimens Measured: 16.
Remarks: Scriniodinium elimatum n. sp. was described as Scriniodinium dictyotum Cookson and Eisenack 1960 by Habib (1974), who implied that there was a gradation from S. dictyotum to Scriniodinium campanula Gocht 1959 within the Berriasian to Valanginian interval of the western North Atlantic. There is some similarity between the less–ornamented specimens of Scriniodinium elimatum n. sp. and Scriniodinium campanula, which supports Habib’s (1974) suggestion of a relationship. However, although Scriniodinium campanula is recorded as old as the Berriasian, Scriniodinium elimatum n. sp. appears to be restricted to the Valanginian and early Hauterivian, suggesting that the latter derived from the former, rather than the other way round, as suggested by Habib (op. cit.). In the UKCS Central North Sea, the highest occurrence of true S. dictyotum is within the mid Kimmeridgian (Duxbury et al. 1999). Riding and Fensome (2003, p. 16) appear to have accepted Habib’s specimens as true S. dictyotum, although their range chart (text-fig. 2) has a similar range top for S. dictyotum to that in Duxbury et al. (op cit.).