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Chichaouadinium vestitum
Chichaouadinium vestitum, (Brideaux, 1971), Bujak and Davies, 1983
Originally Spinidinium, subsequently Deflandrea, thirdly Spinidinium?, fourthly (and now) Chichaouadinium.
Tax. sr. synonym of Deflandrea (subsequently Chichaouadinium) limpida C. Singh, 1971, according to Lentin and Williams, 1973.
Holotype: Brideaux, 1971, pl.29, figs.99, 102-103, text-figs.10a,d
Locus typicus: Chigwell section, Alberta, USA
Stratum typicum: Late Albian-Early Cenomanian
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Original description as Spinidinium vestitum: [Brideaux, 1971, p. 99-101]:
Diagnosis:
Total cyst length, 71 µm; cyst width, 51 µm. Cyst outline pentagonal, the epitract longer than the hypotract; the epitract tapering to a truncated apex; the hypotract tapering slightly with the left antapical portion being prolonged forming a somewhat asymmetrical antapical region.
Cingulum well marked, nearly circular, outlined by low ridges in part spine bearing, or by low spinose ridges;
sulcus distinct, outlined by sinuous ridges, in part ornamented with spines or cones; sulcus widening slightly at the antapex, extending onto the epitract and terminating apically at a row of spines marking the base of plate 1'.
Tabulation outlined in part by irregular rows of intratabular spines; scheme determined as ?4', ?3 a, 7", 0c, 5''', 1--?2''''.
Archeopyle intercalary, the operculum formed of one intercalary, polygonal plate, a portion of the adjacent wall lost by mechanical disruption.
The outer wall layer pine-bearing and thin; the inner wall layer apparent only around the archeopyle opening.
Description:
Cyst constructed of two layers, the two layers closely appressed, the inner wall visible only in optical section or rendered visible by folding or breaking of one or both layers. Cyst outline pentagonal or pentagonal-elongate, the epitract always longer than the hypotract. Apex tapering and truncated, often crowned with a ringlet of four or five small spines; antapex flattened and slightly depressed, the left hand side often prolonged into an antapical prominence ended by a small, obliquely-set spine.
Cingulum distinct, nearly circular, outlined by raised ridges which may be simple, toothed, or which may be reduced to rows of small spines and cones;
prominent sulcus always present, extending onto the epitract, terminated by spine rows and occasionally a sutural ridge interpreted as the base of plate 1'; sulcus extends to the apex, widening slightly or nearly straight, terminated by the antapical plate(s), outlined by raised simple or spinose ridges.
Spines and cones always present on the cyst, 1-4 µm high, sometimes distinctly intratabular and peripheral, as shown by their lineation just inside secondary sutural breaks about the archeopyle on many specimens, and always scattered sparsely and randomly over the outer cyst wall.
Those specimens showing archeopyle structure generally possess an intercalary archeopyle, the operculum formed of one plate and somewhat hexagonal in shape. Many specimens, however, including the holotype show a complex opening in the intercalary position suggesting either mechanical breakage or the possibility of an archeopyle formed of more than one plate. Several specimens possess such an "enlarged" archeopyle in the outer layer with the inner layer clearly exhibiting a hexagonal archeopyle in the intercalary position. In other specimens, parts of the operculum are present between the two wall layers.
Some specimens, either through mechanical breakage, or through regular breakdown along accessory sutures, show breaks on either side of plate 4" or between plates 2", 3" and 4". Approximately a half dozen specimens identical in all respects to the morphology outlined in the preceding paragraphs have an apical break leaving only the pre-cingular and intercalary series intact on the epitract.
Tabulation is not completely shown on any one specimen. It appears that the following scheme, based on observation of the archeopyle structure and breakdown of the sutures, as well as on spine rows and sutural ridges, may be a reasonable attempt: 4', ?3 a, 7", 0c, 5--?6''', ?2''''. Plate 4' is outlined by the apical circlet of spines; plates 1" and 2" are often visible through spine row lineations; plates 3" and 4" may be marked in a similar way and by breakdown of sutures; plates 5", 6" and 7" are marked by spine rows or sutures. Postcingular tabulation is more difficult to determine and is based on spine rows, sutural ridges, and the sulcul outline. It cannot be determined whether one or two antapical plates are present; conditions of symmetry suggest only one. While only the operculum is marked clearly in the intercalary series, it appears again from symmetrical considerations, that there are three plates; the spine rows are not clearly aligned on any specimens recovered and examined in this region.
Dimensions:
Total length on 51 measured specimens, 52-92 µm; width on 53 measured specimens, 31-58 µm.
Affinities:
Spinidinium styloniferum Cookson and Eisenack 1960 differs in construction of wall layers, spine pattern and apex, and in possession of a helicoid cingulum. S. densispinatum Stanley, 1965, p. 226 and S. microceratum Stanley, 1965, p. 227 differ in their shape, slightly helicoid cingulum, and their profusion of intratabular spines, among other characteristics.
Deflandrea echinoidea Cookson and Eisenack, 1960 does not possess a clear relationship of spiny ornament to tabulation. The authors (Ibid, 1960, p. 2) do not mention such a relationship and note only that the "shell membrane is thin and fairly densely covered with thin, stiff spines (up to 5 µm long)."
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Emended dimensions as Deflandrea vestita:
Sverdlove and Habib, 1972, p. 59-60:
Diagnosis:
Bicavate to acavate cysts, peridinioid in outline.
One apical horn; two antapical horns of unequal length, longer horn on left in dorsal view.
Epitract tapers to a tuft of spines at apex.
Circular-based spines, tapering to points distally, formed solely by periphragm, arranged suturally or peritabularly, delineate cyst tabulation: 4', 3a, 7", ?6c, 5''', 1 - 2''''. Variable concentration of intratabular spines present. Average spine length, 1.0 µm; range, 0.5-3.0 µm.
Periphragm between spines smooth to slightly granular. Cyst of two wall layers; pericoels of variable size and volume may develop in apical and antapical horn regions.
Archeopyle intercalary, Type I/I, plate 2a/2a. Cyst walls may develop accessory archeopyle sutures in precingular series, forming irregular excystment apertures.
Cingulum circular to slightly laevorotatory;encircles cyst equatorially.
Sulcus well developed on hypotract; continues onto epitract to base of plate 1'.
Cingulum and sulcus contain few intratabular spines; delineating spines frequently joined proximally causing thickened cyst wall.
Dimensions:
38 specimens were measured. The maximum length varied from 48-73 µm, and the maximum width from 31-61 µm. The apical pericoel length varied from 0-7 µm.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Chichaouadinium vestitum (Brideaux, 1971) Bujak and Davies, 1983, has an epicyst longer than the hypocyst, with the latter having a well developed left antapical horn and less well developed right antapical horn. The cingulum is denoted by small spines or spiny ridges. Tabulation outlined in part by irregular rows of intratabular spines. Spines can occur anywhere on the pericyst.
Size: overall length 52-92 µm, width 31-58 µm.
Originally Spinidinium, subsequently Deflandrea, thirdly Spinidinium?, fourthly (and now) Chichaouadinium.
Tax. sr. synonym of Deflandrea (subsequently Chichaouadinium) limpida C. Singh, 1971, according to Lentin and Williams, 1973.
Holotype: Brideaux, 1971, pl.29, figs.99, 102-103, text-figs.10a,d
Locus typicus: Chigwell section, Alberta, USA
Stratum typicum: Late Albian-Early Cenomanian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description as Spinidinium vestitum: [Brideaux, 1971, p. 99-101]:
Diagnosis:
Total cyst length, 71 µm; cyst width, 51 µm. Cyst outline pentagonal, the epitract longer than the hypotract; the epitract tapering to a truncated apex; the hypotract tapering slightly with the left antapical portion being prolonged forming a somewhat asymmetrical antapical region.
Cingulum well marked, nearly circular, outlined by low ridges in part spine bearing, or by low spinose ridges;
sulcus distinct, outlined by sinuous ridges, in part ornamented with spines or cones; sulcus widening slightly at the antapex, extending onto the epitract and terminating apically at a row of spines marking the base of plate 1'.
Tabulation outlined in part by irregular rows of intratabular spines; scheme determined as ?4', ?3 a, 7", 0c, 5''', 1--?2''''.
Archeopyle intercalary, the operculum formed of one intercalary, polygonal plate, a portion of the adjacent wall lost by mechanical disruption.
The outer wall layer pine-bearing and thin; the inner wall layer apparent only around the archeopyle opening.
Description:
Cyst constructed of two layers, the two layers closely appressed, the inner wall visible only in optical section or rendered visible by folding or breaking of one or both layers. Cyst outline pentagonal or pentagonal-elongate, the epitract always longer than the hypotract. Apex tapering and truncated, often crowned with a ringlet of four or five small spines; antapex flattened and slightly depressed, the left hand side often prolonged into an antapical prominence ended by a small, obliquely-set spine.
Cingulum distinct, nearly circular, outlined by raised ridges which may be simple, toothed, or which may be reduced to rows of small spines and cones;
prominent sulcus always present, extending onto the epitract, terminated by spine rows and occasionally a sutural ridge interpreted as the base of plate 1'; sulcus extends to the apex, widening slightly or nearly straight, terminated by the antapical plate(s), outlined by raised simple or spinose ridges.
Spines and cones always present on the cyst, 1-4 µm high, sometimes distinctly intratabular and peripheral, as shown by their lineation just inside secondary sutural breaks about the archeopyle on many specimens, and always scattered sparsely and randomly over the outer cyst wall.
Those specimens showing archeopyle structure generally possess an intercalary archeopyle, the operculum formed of one plate and somewhat hexagonal in shape. Many specimens, however, including the holotype show a complex opening in the intercalary position suggesting either mechanical breakage or the possibility of an archeopyle formed of more than one plate. Several specimens possess such an "enlarged" archeopyle in the outer layer with the inner layer clearly exhibiting a hexagonal archeopyle in the intercalary position. In other specimens, parts of the operculum are present between the two wall layers.
Some specimens, either through mechanical breakage, or through regular breakdown along accessory sutures, show breaks on either side of plate 4" or between plates 2", 3" and 4". Approximately a half dozen specimens identical in all respects to the morphology outlined in the preceding paragraphs have an apical break leaving only the pre-cingular and intercalary series intact on the epitract.
Tabulation is not completely shown on any one specimen. It appears that the following scheme, based on observation of the archeopyle structure and breakdown of the sutures, as well as on spine rows and sutural ridges, may be a reasonable attempt: 4', ?3 a, 7", 0c, 5--?6''', ?2''''. Plate 4' is outlined by the apical circlet of spines; plates 1" and 2" are often visible through spine row lineations; plates 3" and 4" may be marked in a similar way and by breakdown of sutures; plates 5", 6" and 7" are marked by spine rows or sutures. Postcingular tabulation is more difficult to determine and is based on spine rows, sutural ridges, and the sulcul outline. It cannot be determined whether one or two antapical plates are present; conditions of symmetry suggest only one. While only the operculum is marked clearly in the intercalary series, it appears again from symmetrical considerations, that there are three plates; the spine rows are not clearly aligned on any specimens recovered and examined in this region.
Dimensions:
Total length on 51 measured specimens, 52-92 µm; width on 53 measured specimens, 31-58 µm.
Affinities:
Spinidinium styloniferum Cookson and Eisenack 1960 differs in construction of wall layers, spine pattern and apex, and in possession of a helicoid cingulum. S. densispinatum Stanley, 1965, p. 226 and S. microceratum Stanley, 1965, p. 227 differ in their shape, slightly helicoid cingulum, and their profusion of intratabular spines, among other characteristics.
Deflandrea echinoidea Cookson and Eisenack, 1960 does not possess a clear relationship of spiny ornament to tabulation. The authors (Ibid, 1960, p. 2) do not mention such a relationship and note only that the "shell membrane is thin and fairly densely covered with thin, stiff spines (up to 5 µm long)."
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended dimensions as Deflandrea vestita:
Sverdlove and Habib, 1972, p. 59-60:
Diagnosis:
Bicavate to acavate cysts, peridinioid in outline.
One apical horn; two antapical horns of unequal length, longer horn on left in dorsal view.
Epitract tapers to a tuft of spines at apex.
Circular-based spines, tapering to points distally, formed solely by periphragm, arranged suturally or peritabularly, delineate cyst tabulation: 4', 3a, 7", ?6c, 5''', 1 - 2''''. Variable concentration of intratabular spines present. Average spine length, 1.0 µm; range, 0.5-3.0 µm.
Periphragm between spines smooth to slightly granular. Cyst of two wall layers; pericoels of variable size and volume may develop in apical and antapical horn regions.
Archeopyle intercalary, Type I/I, plate 2a/2a. Cyst walls may develop accessory archeopyle sutures in precingular series, forming irregular excystment apertures.
Cingulum circular to slightly laevorotatory;encircles cyst equatorially.
Sulcus well developed on hypotract; continues onto epitract to base of plate 1'.
Cingulum and sulcus contain few intratabular spines; delineating spines frequently joined proximally causing thickened cyst wall.
Dimensions:
38 specimens were measured. The maximum length varied from 48-73 µm, and the maximum width from 31-61 µm. The apical pericoel length varied from 0-7 µm.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Chichaouadinium vestitum (Brideaux, 1971) Bujak and Davies, 1983, has an epicyst longer than the hypocyst, with the latter having a well developed left antapical horn and less well developed right antapical horn. The cingulum is denoted by small spines or spiny ridges. Tabulation outlined in part by irregular rows of intratabular spines. Spines can occur anywhere on the pericyst.
Size: overall length 52-92 µm, width 31-58 µm.