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Microdinium ornatum

Microdinium ornatum Cookson and Eisenack, 1960

Originally (and now) Microdinium, subsequently Phanerodinium.
Below, 1987, transferred this species to Phanerodinium Deflandre, 1937. Lentin and Williams, 1989, retained it in Microdinium.
Holotype: Cookson and Eisenack, 1960, pl.2, figs.3-4, text-fig.2
Locus typicus: Perth Basin, Australia
Stratum typicum: Albian-Turonian

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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.

Microdinium ornatum Cookson and Eisenack, 1960a, is divided unequally by a relatively broad cingulum, epicyst shorter than hypocyst. Plates bordered by low but distinct ledges, which frequently are perforated by a single row of holes and look like strings of beads in surface view. Sometimes the outer edge of the ledges may be missing ,in which case the portions of the wall originally separating the perforations appear as isolated beads. The surface of the plates may be ornamented by a varying number of small tubercles. Size: length 28-38 µm width 27-36um, holotype length 29 µm, width 27 µm.
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Original description: Cookson and Eisenack, 1966, p. 7
Shell ovoidal, narrower end anteruor, divided unequally by the relatively broad girdle; epitheka shorter than hypotheca. Plates bordered by low but distinct ledges, which frequently are perforated by a single row of holes and looklike strings of beads in suface view. Sometimes the outer edge of the ledges may be missing, in which case the proportions of the wall originally seperating the perforations appear as isolated "beads". The surface of the plates may be ornamented by a varying number of small tubercles.

Supplemental description: Davey, 1969, p. 132
The shell is subspherical to ovoidal possessing a smooth body wall ornamented by a few large tubercles. The latter may be flat or distinctly concave distally. In two specimens small tubercles were seen to delimit a plate in the posterior portion of the ventral area. The plates are bordered by short, broad projections, which may be isolated or united distally. Range of observed specimens: shell length 31--34 Ám, width 23--31 Ám, height of crests 1-2 Ám.
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