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Dinopterygium

From Williams et al., 2017:

[Dinopterygium, Deflandre, 1935, p. 231; Emendations: Stover and Evitt, 1978, p. 204–205; Fensome et al., 2009, p. 27–28.

Type species: Dinopterygium cladoides, Deflandre, 1935 (pl.8, fig.6)]

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Original description: [Deflandre, 1935]: (Translation: Stover and Evitt, 1978):

Description:
The outline, as presented in the figure, recalls that of certain medieval helmets. Its furrow, ornamented with large punctations, is enclosed by two large aliform outgrowths. One of the poles of the theca carries a complicated system of fine membranes, folded in this fossil, rather analogous to those of many Ornithocercacae (Ornithocercus, Histioneis) and recalling also those of several Hystrichosphaeridae.

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Deflandre, 1936, p. 181: (Translation: by LPP):

Remarks:
The single specimen I possess of the type species of this dinoflagellate, Dinopterygium cladoides Defl., does not allow for a complete examination. From a generic point of view, it may be characterized by the possession of a very straight transverse furrow, framed by two very large, thin membranous expansions, and by the development of a system of thin membranes and aliform crests, related to a tabulation encompassing a number of slightly elevated plates; this number seems smaller than that of the other genera in the Peridiniales, the group to which Dinoptrerygium may be assigned without doubt.

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Emended description:


Stover and Evitt, 1978:

Synopsis:
Cysts proximochorate, subspherical to subpolygonal; outline circular, or nearly so, in apical-antapical view; paratabulation gonyaulacacean, indicated by parasutural septa and by intratabular structures between autophragm and ectophragm; combination epicystal archeopyle, Type tAtP.

Description:
Shape: Subspherical to subpolyhedral; outline circular, or nearly so, in apical-antapical view.
Wall relationships: Autophragm and ectophragm narrowly separated across intratabular areas, more widely separated between intratabular areas; ectophragm thin, smooth or faintly ornamented.
Wall features: Parasutural septa thin and commonly folded, except in equatorial area, and may be perforate. Groups of tubercles or short, hollow, cylindrical structures occur in intratabular areas beneath ectophragm.
Paratabulation: Indicated by parasutural septa and by intratabular groups of structures; gonyaulacacean, formula: 4`, 6``, Xc, 6```,1p, 1````, 1ps.
Archeopyle: Combination epicystal archeopyle, Type tAtP; principal archeopyle suture straight and within paracingulum.
Paracingulum: Indicated by two parallel transverse septa; area between septa smooth or has transverse rows of short projections.
Parasulcus: Indicated by convexities in transverse septa or by depressed area on hypocyst, or both.
Size: Intermediate.

Affinities:
Dinopterygium differs from Heteraulacacysta in having intratabular clusters of structures, usually tubercules, whereas on Heteraulacacysta the ornamentation of the autophragm (when present) is uniformly distributed. Dinopterygium and Tubidermodinium are similar in that each has intratabular clusters of structures; however, in the parasutural areas the ectophragm is depressed on Tubidermodinium but elevated on Dinopterygium.
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