Back
Burtonia polygonalis
Burtonia polygonalis, Beju, 1983
Now Atopodinium. Originally Burtonia, subsequently Bejuia, thirdly (and now) Atopodinium.
Holotype: Beju, 1983, text-figs.3A-B, 4A-B; Masure, 1991, pl.2, figs.1,4; text-figs.3a-b,4a-b
Locus typicus: Burton Cliff outcrop section, at Burton Bradstock, southeast of Bridport, Dorset, England
Stratum typicum: Early Bathonian, Zigzagiceras zigzag Zone, Oppelia yeovilensis Subzone
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Beju, 1983, p.107-109]:
Description:
Dorso-ventrally compressed subpolygonal proximate dinocysts with a rounded to flattened to slightly protuberant apex; antapex provided with a prominent subquadrate protuberance.
Test single-layered (autocyst), laevigate, relatively thin (ca. 1 µm) with the exception of the antapex, where it thickens to form the antapical protuberance and has a coarsely granular surface.
Paracingulum discernible on the ventral surface of most specimens examined, comparatively broad, strongly offset, delineated by low and narrow ridges. Its continuation on the dorsal side is less obviously expressed and appears to be strongly displaced in apical direction (Figures 4B, D, F; 5B, D), corresponding to the anterior dorsal outline of the cyst. Consequently, the dorsal side of the epicyst is considerably reduced, and the whole epicyst, which is significantly smaller than the hypocyst, is displaced ventrally.
Paratabulation not fully expressed and/or determinable on the specimen recovered. However, the hypocyst appears to be formed by six paraplates delineated by low, narrow, sometimes discontinuous ridges on the ventral side, and more clearly expressed ridges on the dorsal side. Three dorsal postcingular paraplates are clearly determinable on all specimens found. The central dorsal paraplate, which may be equivalent to the 4th postcingular plate of the gonyaulacid pattern, is comparatively large, subtrapezoidal, and extends from the paracingulum to the antapex. The two lateral dorsal postcingular plates, which may correspond to plates 3""" and 5""" of the gonyaulacid pattern, are elongated subrectangular, somewhat narrower than the central plate. Three elongated subrectangular paraplates are discernible on the ventral postcingular side; these may correspond to paraplates 1""", 2""", 6""" of the gonyaulacid model.
A slightly depressed longitudinal area between paraplates 1""" and 6""" probably indicates the parasulcus.
In addition, a transversal, thickened, granular plate or "shield" is located on the ventral antapical margin of the hypocyst (Figures 4A, C, E; 5C).
The epicystal paratabulation not clearly expressed on any of the specimens recovered.
Archeopyle formation not clearly discernible in optical microscopy.
Now Atopodinium. Originally Burtonia, subsequently Bejuia, thirdly (and now) Atopodinium.
Holotype: Beju, 1983, text-figs.3A-B, 4A-B; Masure, 1991, pl.2, figs.1,4; text-figs.3a-b,4a-b
Locus typicus: Burton Cliff outcrop section, at Burton Bradstock, southeast of Bridport, Dorset, England
Stratum typicum: Early Bathonian, Zigzagiceras zigzag Zone, Oppelia yeovilensis Subzone
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Beju, 1983, p.107-109]:
Description:
Dorso-ventrally compressed subpolygonal proximate dinocysts with a rounded to flattened to slightly protuberant apex; antapex provided with a prominent subquadrate protuberance.
Test single-layered (autocyst), laevigate, relatively thin (ca. 1 µm) with the exception of the antapex, where it thickens to form the antapical protuberance and has a coarsely granular surface.
Paracingulum discernible on the ventral surface of most specimens examined, comparatively broad, strongly offset, delineated by low and narrow ridges. Its continuation on the dorsal side is less obviously expressed and appears to be strongly displaced in apical direction (Figures 4B, D, F; 5B, D), corresponding to the anterior dorsal outline of the cyst. Consequently, the dorsal side of the epicyst is considerably reduced, and the whole epicyst, which is significantly smaller than the hypocyst, is displaced ventrally.
Paratabulation not fully expressed and/or determinable on the specimen recovered. However, the hypocyst appears to be formed by six paraplates delineated by low, narrow, sometimes discontinuous ridges on the ventral side, and more clearly expressed ridges on the dorsal side. Three dorsal postcingular paraplates are clearly determinable on all specimens found. The central dorsal paraplate, which may be equivalent to the 4th postcingular plate of the gonyaulacid pattern, is comparatively large, subtrapezoidal, and extends from the paracingulum to the antapex. The two lateral dorsal postcingular plates, which may correspond to plates 3""" and 5""" of the gonyaulacid pattern, are elongated subrectangular, somewhat narrower than the central plate. Three elongated subrectangular paraplates are discernible on the ventral postcingular side; these may correspond to paraplates 1""", 2""", 6""" of the gonyaulacid model.
A slightly depressed longitudinal area between paraplates 1""" and 6""" probably indicates the parasulcus.
In addition, a transversal, thickened, granular plate or "shield" is located on the ventral antapical margin of the hypocyst (Figures 4A, C, E; 5C).
The epicystal paratabulation not clearly expressed on any of the specimens recovered.
Archeopyle formation not clearly discernible in optical microscopy.