Back
Dissiliodinium willei
Dissiliodinium willei Bailey and Partington, 1991
Holotype: Bailey and Partington, 1991, pl.1, fig.1, text-fig.2
Locus typicus: UKCS Well 9/9b- 10 at 3550.70m (conventional core).
Stratum typicum: Early Bajocian-Callovian
Original diagnosis: Bailey and Partington, 1991, p.246
Subspherical to ellipsoidal proximate gonyaulacoid dinocyst. Autophragm variously ornamented with low relief granulate, vermiculate and reticulate sculpture. Tabulation absent, indicated by archaeopyle only (type 1P-5P). Average size 75x60 Ám (holotype 81x63 Ám).
Original description: Bailey and Partington, 1991, p.246
The cyst outline is often modified by one or two strong, sub-parallel tolds. The autophragm is ornamented by low relief features which vary in complexity, from isolated low mounds orgranules, to more elongate and branching vermiculae, which may develop into an incomplete reticulum. This variation in ornament is often seen on a single specimen. Tabulation is generally indicated by the archaeopyle only, but in some rare forms with stronger ornament, individual elements may merge to form partial cingular parasutures. The archaeopyle is formed by the loss of up to five precingular plates. Size intermediate, generally around 70 Ám in length and 50 Ám width.
Affinities:
Bailey and Partington, 1991, p.246: Dissiliodinium willei is distinguished from other species of the genus by the style of ornament. The low undulose vermiculae and reticulate areas are coarser and distributed in a more open pattern than in D. globulum (Drugg, 1978).
--------------------------------------------------------------------------------------------------------------------------------------------------
Poulsen 1996, p. 80
cf. Dissiliodinium willei Bailey & Partington 1991, Pl. 19, Figs. 4-5
Remarks. The specimens found in this study and referred to cf. D. willei or possibly to Dissiliodinium? sp. A of Feist-Burkhardt 1990 mainly comprise opercular pieces and other fragments of disintegrated cysts, together with a few folded cysts (Pl. 19, Fig. 9).
Occurrences. Dissiliodinium willei occurs in the Early Bajocian to Callovian, where it often is present in high numbers in marginal marine sediments from the North Sea and adjacent areas (Bailey and Partington, 1991). Dissiliodinium? sp. A of Feist-Burkhardt occurs in the Aalenian to Middle Bajocian of southern Germany and Switzerland (Feist-Burkhardt, 1990). In Denmark, it is recorded in the Middle Jurassic.
The two species have similar wall ornaments, but Dissiliodinium? sp. A differs from other species of Dissiliodinium in having a dorsal intercalary paraplate (Feist-Burkhardt, 1990). The state of preservation of the specimens found in this study do not allow certain identification. The Toarcian to Middle Bajocian granulate specimens of Kallosphaeridium, referred to the Tertiary species Kallosphaeridium capulatum Stover 1977 emend. Jan du Chene et al. 1984 by Prauss (1989), may be synonymous with Dissiliodinium sp. A of Feist-Burkhardt.
Holotype: Bailey and Partington, 1991, pl.1, fig.1, text-fig.2
Locus typicus: UKCS Well 9/9b- 10 at 3550.70m (conventional core).
Stratum typicum: Early Bajocian-Callovian
Original diagnosis: Bailey and Partington, 1991, p.246
Subspherical to ellipsoidal proximate gonyaulacoid dinocyst. Autophragm variously ornamented with low relief granulate, vermiculate and reticulate sculpture. Tabulation absent, indicated by archaeopyle only (type 1P-5P). Average size 75x60 Ám (holotype 81x63 Ám).
Original description: Bailey and Partington, 1991, p.246
The cyst outline is often modified by one or two strong, sub-parallel tolds. The autophragm is ornamented by low relief features which vary in complexity, from isolated low mounds orgranules, to more elongate and branching vermiculae, which may develop into an incomplete reticulum. This variation in ornament is often seen on a single specimen. Tabulation is generally indicated by the archaeopyle only, but in some rare forms with stronger ornament, individual elements may merge to form partial cingular parasutures. The archaeopyle is formed by the loss of up to five precingular plates. Size intermediate, generally around 70 Ám in length and 50 Ám width.
Affinities:
Bailey and Partington, 1991, p.246: Dissiliodinium willei is distinguished from other species of the genus by the style of ornament. The low undulose vermiculae and reticulate areas are coarser and distributed in a more open pattern than in D. globulum (Drugg, 1978).
--------------------------------------------------------------------------------------------------------------------------------------------------
Poulsen 1996, p. 80
cf. Dissiliodinium willei Bailey & Partington 1991, Pl. 19, Figs. 4-5
Remarks. The specimens found in this study and referred to cf. D. willei or possibly to Dissiliodinium? sp. A of Feist-Burkhardt 1990 mainly comprise opercular pieces and other fragments of disintegrated cysts, together with a few folded cysts (Pl. 19, Fig. 9).
Occurrences. Dissiliodinium willei occurs in the Early Bajocian to Callovian, where it often is present in high numbers in marginal marine sediments from the North Sea and adjacent areas (Bailey and Partington, 1991). Dissiliodinium? sp. A of Feist-Burkhardt occurs in the Aalenian to Middle Bajocian of southern Germany and Switzerland (Feist-Burkhardt, 1990). In Denmark, it is recorded in the Middle Jurassic.
The two species have similar wall ornaments, but Dissiliodinium? sp. A differs from other species of Dissiliodinium in having a dorsal intercalary paraplate (Feist-Burkhardt, 1990). The state of preservation of the specimens found in this study do not allow certain identification. The Toarcian to Middle Bajocian granulate specimens of Kallosphaeridium, referred to the Tertiary species Kallosphaeridium capulatum Stover 1977 emend. Jan du Chene et al. 1984 by Prauss (1989), may be synonymous with Dissiliodinium sp. A of Feist-Burkhardt.