Heterosestrum formosum ( Tochilina, 1970 )

Popova, Irina M., Baumgartner, Peter O., Guex, Jean, Tochilina, Svetlana V. & Glezer, Zoya I., 2002, Radiolarian biostratigraphy of Paleogene deposits of the Russian Platform (Voronesh Anticline), Geodiversitas 24 (1), pp. 7-59 : 33

Heterosestrum formosum ( Tochilina, 1970) ( Fig 10D, G ; 12O )

Hexacyclia formosa Tochilina, 1970: 175 , figs 2, 3; 1972, pl. 5, figs 1, 2, 5.

Heterosestrum formosum – Petrushevskaya & Kozlova 1979: 103, figs 441-445.

Amphicyclia pentaspina Tochilina, 1972: 136 , pl. 4.

Stylodictya variabilis BjØrklund & Kellogg, 1972: 391 , pl. 1, figs 5, 9a, b.

Staurocromyum densum – Gorbunov 1979: 94, pl. 1, fig. 4.

Stylodictya tschuenkoi – Gorbunov 1979: pl. 13, fig. 1a-g.

Heterosestrum sp. cf. schabalkini – Kozlova 1999: pl. 34, figs 3, 6.

Heterosestrum sp. cf. tschujenkoi – Kozlova 1999: 92, pl. 29, fig. 8.

GEOGRAPHIC DISTRIBUTION. — California, Norwegian Sea, Western Siberia, Russian Platform.

STRATIGRAPHIC RANGE. — Early-middle Eocene of Norwegian Sea, Plato VØring ( BjØrklund & Kellogg 1972; Petrushevskaya & Kozlova 1979); early-middle Eocene (this study).

REMARKS

The images and descriptions of all the species mentioned below are very much similar and to our point of view they represent a group of different local morphotypes of Stylodictya sexispinata . For that reason it is better not to join them together under the same specific name, but to use their original names, to indicate their different geographical domains:

Stylodictya sexispinata Clark & Campbell, 1942: 45 , pl. 3, fig. 7.

Stylodictya schabalkini Lipman, 1949: 116 , pl. 13, fig. 8. Stylodictya magnifica Lipman, 1950: 60 , pl. 1, fig. 13.

Distriacti (?) hexagona Lipman, 1953: 142, pl. VII, fig. 8. Porodiscus turgaicus Lipman, 1953: 144 , pl. VII, fig. 10. Stylodictya tschujenkoi Lipman, 1953: 145 , pl. VII, fig. 11. Stylodictya zonata Lipman, 1953: 146 , pl. 7, figs 8, 10- 12. — Gorbunov 1979: pl. 6, fig. 1a-d.

Staurocromyum densum Kozlova in Kozlova & Gorbovets, 1966: 57, pl. VIII, figs 6, 7.

Figures

FIG. 10. — Early Eocene Radiolarian association, Petropavlovka Village, Well 730, interval 44.3 m; A, B, Periphaena perplexus (Clark & Campbell, 1942); C, F, J, Haliomma (?) faceta (Krasheninnikov, 1960); D, G, Heterosestrum formosum (Tochilina, 1970); E, Periphaena sp. aff. Heliodiscus inca (Clark & Campbell, 1942); H, K, Stylotrochus festivus Clark & Campbell, 1942; I, Heterosestrum (?) sp.; L, M, Amphicraspedium praemurrayanum Kozlova, 1999; N, Ommatogramma biconstrictus (Lipman, 1953). Scale bars: 100 µm.

FIG. 12. — Middle Eocene Radiolarian association, Pirogovo Village, Well 510C, interval 44.0 m (except 8: 730C, 44.3 m); A, Ceratocyrtis charlestonensis (Clark & Campbell, 1945); B, E, F, Ceratocyrtis sp. aff. stigi (Bjørklünd, 1976); C, Lithomelissa spongiosa Bütschli, 1882; D, N, Giraffospyris didiceros (Ehrenberg, 1875); G, Patagospyris morkleyensis (Clark & Campbell, 1942); H, K, Giraffospyris sp. aff. didiceros (Ehrenberg, 1875); I, J, Petalospyris tumidula Kozlova, 1966; L, M, Peripyramis magnifica (Clark & Campbell, 1942) sensu Kozlova 1999; O, Heterosestrum formosum (Tochilina, 1970), saggittal view. Scale bars: 50 µm.