Back
Scriniodinium elimatum
From Fensome et al., 2019:
Scriniodinium elimatum
---------------------------------------------------------------------------------------------------
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
---------------------------------------------------------------------------------------------------
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.).