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Parvocavatus spinosus
Parvocavatus spinosus Duxbury, 1977
Now Dingodinium?. Originally Parvocavatus, subsequently Dingodinium, thirdly (and now) Dingodinium?.
Holotype: Duxbury, 1977, pl.9, fig.3; text-fig. 17
Locus typicus: Speeton Clay, Speeton, England
Stratum typicus: Berriasian
Original diagnosis: Duxbury, 1977, p. 46
A proximo-cavate cyst with a fairly short, open apical horn and with the body surface divided into discrete fields by low sutural crests. The ornament of the endoblast consists of numerous short, distally pointed to flattened elements. The periphragm is smooth to finely granular. Each sutural crest bears numerous delicate spines whose length may vary along the crest length. The sutural spines around the cingulum are long compared to those over the rest of the test. Archeopyle apical, formed by a zig-zag split between apical and precingular plates. The operculum is rarely completely detached.
Original description: Duxbury, 1977, p. 46-47
The overall shape is rounded polygonal. The endoblast is usually relatively rigid and intact but the thinner, more delicate periblast is commonly folded and it is only in exceptional specimens that the full extent of the cavation is seen. The surface of the endoblast is covered with short, spinose elements, except at the apical pole which appears devoid of such ornament. Tabulation is outlined on the periphragm by low sutural crests bearing delicate spines. Unfortunately, in the present study it was not possible to forrnulate a precise tabulation scheme since the large majority of specimens were badly distorted. The tabulation nevertheless appears typically gonyaulacacean, this being supported by Evitt"s illustration (1961, pl. 5, fig. 7). The archeopyle is apical and is formed by splitting of the test along a zig-zag line between the apical and precingular plates. The operculum usually remains attached, probably in the sulcal area as in the genus Dingodinium. The degree of cavation is greatest in the hypotract and least in the cingular area. As a rule, the greater the separation of the body layers, the larger the reduction in sutural ornament height at the point of separation. Consequently the cingulum possesses the longest sutural spines.
Dimensions:
Holotype 65 x 51 µm. Overall 69(59)51 x 53(43)41 µm.
Now Dingodinium?. Originally Parvocavatus, subsequently Dingodinium, thirdly (and now) Dingodinium?.
Holotype: Duxbury, 1977, pl.9, fig.3; text-fig. 17
Locus typicus: Speeton Clay, Speeton, England
Stratum typicus: Berriasian
Original diagnosis: Duxbury, 1977, p. 46
A proximo-cavate cyst with a fairly short, open apical horn and with the body surface divided into discrete fields by low sutural crests. The ornament of the endoblast consists of numerous short, distally pointed to flattened elements. The periphragm is smooth to finely granular. Each sutural crest bears numerous delicate spines whose length may vary along the crest length. The sutural spines around the cingulum are long compared to those over the rest of the test. Archeopyle apical, formed by a zig-zag split between apical and precingular plates. The operculum is rarely completely detached.
Original description: Duxbury, 1977, p. 46-47
The overall shape is rounded polygonal. The endoblast is usually relatively rigid and intact but the thinner, more delicate periblast is commonly folded and it is only in exceptional specimens that the full extent of the cavation is seen. The surface of the endoblast is covered with short, spinose elements, except at the apical pole which appears devoid of such ornament. Tabulation is outlined on the periphragm by low sutural crests bearing delicate spines. Unfortunately, in the present study it was not possible to forrnulate a precise tabulation scheme since the large majority of specimens were badly distorted. The tabulation nevertheless appears typically gonyaulacacean, this being supported by Evitt"s illustration (1961, pl. 5, fig. 7). The archeopyle is apical and is formed by splitting of the test along a zig-zag line between the apical and precingular plates. The operculum usually remains attached, probably in the sulcal area as in the genus Dingodinium. The degree of cavation is greatest in the hypotract and least in the cingular area. As a rule, the greater the separation of the body layers, the larger the reduction in sutural ornament height at the point of separation. Consequently the cingulum possesses the longest sutural spines.
Dimensions:
Holotype 65 x 51 µm. Overall 69(59)51 x 53(43)41 µm.