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Dingodinium europaeum
From Fensome et al., 2019:
Dingodinium europaeum Eisenack, 1958a, p.392–393, pl.24, fig.4. Emendation: Sarjeant, 1985a, p.85,87. Holotype: Eisenack, 1958a, pl.24, fig.4. Age: late Aptian.
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Translation Eisenack, 1958: Sarjeant, 1985
Original diagnosis: Eisenack, 1958, p.392
Shell longer than broad; the thin and transparent outer membrane tapers into an apical prominence, whilst the opposite [antapical] end is broad and rounded. The transverse-furrow-like fold of the membrane lies obliquely in the lower half. The oval, excentrically situated and darker inner body is smooth-walled.
Emended diagnosis: Sarjeant, 1985, p.85, 87
Camocavate to delphicavate, cryptotabulate cysts. Periblast subpolygonal to almost lozenge-shaped, with a strong, tapering, truncate apical horn. Epitract (horn excluded) and hypotract of periblast of comparable size and shape; periphragrn thin and transparent, laevigate. Endoblast broadly ovoidal, situated excentrically, being much closer to the apex than to the antapex so that the posterior peripyle is larger than the anterior.
Endophragm thicker than periphragm, darker in colour, laevigate. Pericingulum well marked by surficial ridges and quite strongly laevorotatory; similar ridges mark the boundaries of some paraplates, but a paratabulation is not fully indicated. Archaeopyle character within the range quoted for Dingodinium by Mehrotra and Sarjeant (1984, p.295).
Dimensions: Holotype (in oblique lateral view): overall length 62 µm, overall breadth 48 µm, length of endoblast 38 µm, breadth 33 µm. Unique.
Affinities:
Sarjeant, 1985, p.87: Since only a single specimen was available for study, and that in lateral view, much remains to be learned about this species. The development of an archaeopyle that has opened and then closed is suggested by a crack at upper left (see Plate I, 3). The peripyle appears to have involved all the apical paraplates, but the nature of the endopyle (variable in this genus) remains obscure. The manner in which the sulcus is expressed and the extent of variation likewise remain to be ascertained. (Another species, D. cerviculum, is known to be highly variable in its morphology; see Mehrotra and Sarjeant, 1984, pp. 298, 300, for discussion.)
Despite these uncertainties, Dingodinium europaeum may be distinguished from other species of the genus by the shape of the apical horn, the proportionately small size of the endoblast and the lack of ornamentation on the endoblast. It is known only from the Upper Aptian.
Dingodinium europaeum Eisenack, 1958a, p.392–393, pl.24, fig.4. Emendation: Sarjeant, 1985a, p.85,87. Holotype: Eisenack, 1958a, pl.24, fig.4. Age: late Aptian.
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Translation Eisenack, 1958: Sarjeant, 1985
Original diagnosis: Eisenack, 1958, p.392
Shell longer than broad; the thin and transparent outer membrane tapers into an apical prominence, whilst the opposite [antapical] end is broad and rounded. The transverse-furrow-like fold of the membrane lies obliquely in the lower half. The oval, excentrically situated and darker inner body is smooth-walled.
Emended diagnosis: Sarjeant, 1985, p.85, 87
Camocavate to delphicavate, cryptotabulate cysts. Periblast subpolygonal to almost lozenge-shaped, with a strong, tapering, truncate apical horn. Epitract (horn excluded) and hypotract of periblast of comparable size and shape; periphragrn thin and transparent, laevigate. Endoblast broadly ovoidal, situated excentrically, being much closer to the apex than to the antapex so that the posterior peripyle is larger than the anterior.
Endophragm thicker than periphragm, darker in colour, laevigate. Pericingulum well marked by surficial ridges and quite strongly laevorotatory; similar ridges mark the boundaries of some paraplates, but a paratabulation is not fully indicated. Archaeopyle character within the range quoted for Dingodinium by Mehrotra and Sarjeant (1984, p.295).
Dimensions: Holotype (in oblique lateral view): overall length 62 µm, overall breadth 48 µm, length of endoblast 38 µm, breadth 33 µm. Unique.
Affinities:
Sarjeant, 1985, p.87: Since only a single specimen was available for study, and that in lateral view, much remains to be learned about this species. The development of an archaeopyle that has opened and then closed is suggested by a crack at upper left (see Plate I, 3). The peripyle appears to have involved all the apical paraplates, but the nature of the endopyle (variable in this genus) remains obscure. The manner in which the sulcus is expressed and the extent of variation likewise remain to be ascertained. (Another species, D. cerviculum, is known to be highly variable in its morphology; see Mehrotra and Sarjeant, 1984, pp. 298, 300, for discussion.)
Despite these uncertainties, Dingodinium europaeum may be distinguished from other species of the genus by the shape of the apical horn, the proportionately small size of the endoblast and the lack of ornamentation on the endoblast. It is known only from the Upper Aptian.