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Distatodinium ellipticum
Distatodinium ellipticum (Cookson, 1965) Eaton, 1976
Originally Hystrichosphaeridium, subsequently Tanyosphaeridium, thirdly (and now) Distatodinium.
Holotype: Cookson, 1965, pl. 11, fig. 1
Paratype: Cookson, 1965, pl. 11, fig. 2
Locus typicus: Brown's Creek Greensand, Aire District, SW Victoria, Australia
Stratum typicum: Late Eocene
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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.
Distatodinium ellipticum (Cookson, 1965) Eaton, 1976, has 35-40 hollow processes of varying length and width which tend to be more numerous at the poles. Processes simple or branched, unequal in size, narrowing along their length to broaden again distally, where they are funnel shaped, varying in width and depth, rims fringed with fine, branched processes, the ultimate branchlets frequently only visible under oil. Size: holotype, overall 187 µm, width 109 µm, central body 101 x 52 µm. Processes 21-39 µm.
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Original description: Cookson, 1965, p. 87: Hystrichosphaeridium ellipticum
Description: Shell elliptical in outline, untabulated, thin-walled with about 30-45 hollow appendages of varying lengths and widths which tend to be more numerous in the vicinity of apex and antapex (pl. 11, fig. 2, 3). Archeopyle apical with a truncate edge. Appendages simple or branched, unequal in size, narrowing distally from base to broaden again apically; apices funnel-shaped, varying considerably in both width and depth, rims fringed with fine, branched processes the ultimate branchlets frequently visible only under oil immersion (pl. 11, fig. 3a) cavities of appendages traceable to the main processes fringing the rims (pl. 11, fig. 3a). Shell-membrane c. 0.5 Ám or less thick, two-layered, outer layer smooth in optical section, finely and closely granular in surface view, sometimes more conspicuously so near the bases of the appendages especially at the antapex.
Dimensions: Holotype-overall length c. 187 Ám, overal width c. 109 Ám; shell 101 x 52 Ám. Range-three open shells, length 83 Ám, width 47-52 Ám; appendages 21-39 Ám long.
Supplemental description: Eaton, 1976, p. 264-265
The cyst body has an elongate oval outline and a smooth or finely granular surface. The processes are variable in breadth, simple or branched, typically flattened and blade-like in cross-section, and distally and proximally expanded. Distally they are bifurcate or trifurcate with complex secondary and tertiary branchlets, the ramifications having a twig-like appearance. The number of processes varies from about 40 to about 60. They appear to be present over all zones of the cyst body, but frequently show a greater concentration towards the apex and antapex. The processes show some alignment into rings around the cyst body, and a definte alignment into rows parallel to its long axis. The straight or curved lines marking the divergence of the processes from the cyst body are also parallel to the long axis. Occasionally processes occur which are T-shaped in cross-section. Adjacent longitudinally aligned processes may be proximally united by membrane, particularly at the antapex. Archaeopyle apical.
Dimensions: Observed range: cyst body (without operculum) 40 x 25 Ám to 73 x 48 Ám; processes, length up to 30 Ám, breadth up to 7 Ám. (n = 24).
Remarks: The flattened processes appear to be essentially solid, particularly in the proximal region. Occasionally the distal ramifications may be hollow (Cookson, 1965: 87; pl. 11, fig. 3a) and some specimens of D. ellipticum have been reorded here with a few slender tubular processes. The flattening and alignment of the processes parallel to the long axis of the cyst body in D. ellipticum may indicate that the processes are basically sutural in positionm, and the occasional process which is T-shaped in cross-section is probably gonal in position. However, the processes cannot be attributed to reflected tabulation zones readily as in D. craterum, and their occasional arrangement in arcyate complexes complicates the interpretation of process distribution in D. ellipticum.
Affinities:
Cookson, 1965, p. 87: Hystrichosphaeridium ellipticum
A close affinity is evident between H. ellipticum and H. paradoxum Brosius 1963 from certain German mid-Oligocene deposits. Both have elongate-oval shells and funnel-shaped appendages of varying lengths and widths. However, judging by the illustrations of Brosius, the number of appendages in H. paradoxum (unfortunately not specified in the text) is considerably lower than that in H. ellipticum. Moreover, the long 'flagelliform' processes bordering the rims of the appendages (Brosius loc. cit. Abb 2) are shown as unbranched in contrast to the secondary and teriary branchlets of H. ellipticum. In addition, the dimensions of open shells of H. ellipticum considerably exceed those given for H. paradoxum.
Originally Hystrichosphaeridium, subsequently Tanyosphaeridium, thirdly (and now) Distatodinium.
Holotype: Cookson, 1965, pl. 11, fig. 1
Paratype: Cookson, 1965, pl. 11, fig. 2
Locus typicus: Brown's Creek Greensand, Aire District, SW Victoria, Australia
Stratum typicum: Late Eocene
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Distatodinium ellipticum (Cookson, 1965) Eaton, 1976, has 35-40 hollow processes of varying length and width which tend to be more numerous at the poles. Processes simple or branched, unequal in size, narrowing along their length to broaden again distally, where they are funnel shaped, varying in width and depth, rims fringed with fine, branched processes, the ultimate branchlets frequently only visible under oil. Size: holotype, overall 187 µm, width 109 µm, central body 101 x 52 µm. Processes 21-39 µm.
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Original description: Cookson, 1965, p. 87: Hystrichosphaeridium ellipticum
Description: Shell elliptical in outline, untabulated, thin-walled with about 30-45 hollow appendages of varying lengths and widths which tend to be more numerous in the vicinity of apex and antapex (pl. 11, fig. 2, 3). Archeopyle apical with a truncate edge. Appendages simple or branched, unequal in size, narrowing distally from base to broaden again apically; apices funnel-shaped, varying considerably in both width and depth, rims fringed with fine, branched processes the ultimate branchlets frequently visible only under oil immersion (pl. 11, fig. 3a) cavities of appendages traceable to the main processes fringing the rims (pl. 11, fig. 3a). Shell-membrane c. 0.5 Ám or less thick, two-layered, outer layer smooth in optical section, finely and closely granular in surface view, sometimes more conspicuously so near the bases of the appendages especially at the antapex.
Dimensions: Holotype-overall length c. 187 Ám, overal width c. 109 Ám; shell 101 x 52 Ám. Range-three open shells, length 83 Ám, width 47-52 Ám; appendages 21-39 Ám long.
Supplemental description: Eaton, 1976, p. 264-265
The cyst body has an elongate oval outline and a smooth or finely granular surface. The processes are variable in breadth, simple or branched, typically flattened and blade-like in cross-section, and distally and proximally expanded. Distally they are bifurcate or trifurcate with complex secondary and tertiary branchlets, the ramifications having a twig-like appearance. The number of processes varies from about 40 to about 60. They appear to be present over all zones of the cyst body, but frequently show a greater concentration towards the apex and antapex. The processes show some alignment into rings around the cyst body, and a definte alignment into rows parallel to its long axis. The straight or curved lines marking the divergence of the processes from the cyst body are also parallel to the long axis. Occasionally processes occur which are T-shaped in cross-section. Adjacent longitudinally aligned processes may be proximally united by membrane, particularly at the antapex. Archaeopyle apical.
Dimensions: Observed range: cyst body (without operculum) 40 x 25 Ám to 73 x 48 Ám; processes, length up to 30 Ám, breadth up to 7 Ám. (n = 24).
Remarks: The flattened processes appear to be essentially solid, particularly in the proximal region. Occasionally the distal ramifications may be hollow (Cookson, 1965: 87; pl. 11, fig. 3a) and some specimens of D. ellipticum have been reorded here with a few slender tubular processes. The flattening and alignment of the processes parallel to the long axis of the cyst body in D. ellipticum may indicate that the processes are basically sutural in positionm, and the occasional process which is T-shaped in cross-section is probably gonal in position. However, the processes cannot be attributed to reflected tabulation zones readily as in D. craterum, and their occasional arrangement in arcyate complexes complicates the interpretation of process distribution in D. ellipticum.
Affinities:
Cookson, 1965, p. 87: Hystrichosphaeridium ellipticum
A close affinity is evident between H. ellipticum and H. paradoxum Brosius 1963 from certain German mid-Oligocene deposits. Both have elongate-oval shells and funnel-shaped appendages of varying lengths and widths. However, judging by the illustrations of Brosius, the number of appendages in H. paradoxum (unfortunately not specified in the text) is considerably lower than that in H. ellipticum. Moreover, the long 'flagelliform' processes bordering the rims of the appendages (Brosius loc. cit. Abb 2) are shown as unbranched in contrast to the secondary and teriary branchlets of H. ellipticum. In addition, the dimensions of open shells of H. ellipticum considerably exceed those given for H. paradoxum.