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Rivernookia septata
Rivernookia septata (Cookson and Eisenack, 1967, p.253-254) Cookson and Eisenack, 1982, p.56
NOW Hafniasphaera. Originally Baltisphaeridium (Appendix A), subsequently Spiniferites, thirdly (and now) Hafniasphaera, fourthly Achomosphaera, fifthly Rivernookia.
Lentin and Williams, 1985, retained the species in Hafniasphaera Hansen, 1977.
Stover and Williams, 1987, retained the species in Spiniferites Mantell, 1850.
Holotype: Cookson and Eisenack, 1967, pl.42, fig.6
Locus typicus: Rivernook Member of Dilwyn Clay, Victoria, Australia
Stratum typicum: Late Paleocene
Original diagnosis: Cookson and Eisenack, 1967, p.253: Baltisphaeridium septatum
Shell spherical, thin-walled with a closely and rather coarsely apparently granular surface and a variable number of radially arranged appendages which approximate in length to the radius of the shell. A "marginal zone" often present, given the impression that the shell is thick-walled, is, in fact, due to compression.
Original description: Cookson and Eisenack, 1967, p.253: Baltisphaeridium septatum
The appendages vary in size, shape and structure. The majority narrow somewhat from a broadened base and divide distally into two or three straight or curved tapering branches with closed, pointed or minutely bifurcate tips. The larger appendages are typically hollow and septate throughout; in the finer to thread-like ones, on the contrary the degree of septation is often difficult to determine and their distal portions, at least, appear to be solid. A few of the appendages are unbranched. A pylome has been seen in a few specimens.
Dimensions: Holotype: overall diameter c. 80 µm diameter of shell c. 57 µm, appendages 10 - 18 µm long. Range: shell diameter c. 42 - 58 µm.
NOW Hafniasphaera. Originally Baltisphaeridium (Appendix A), subsequently Spiniferites, thirdly (and now) Hafniasphaera, fourthly Achomosphaera, fifthly Rivernookia.
Lentin and Williams, 1985, retained the species in Hafniasphaera Hansen, 1977.
Stover and Williams, 1987, retained the species in Spiniferites Mantell, 1850.
Holotype: Cookson and Eisenack, 1967, pl.42, fig.6
Locus typicus: Rivernook Member of Dilwyn Clay, Victoria, Australia
Stratum typicum: Late Paleocene
Original diagnosis: Cookson and Eisenack, 1967, p.253: Baltisphaeridium septatum
Shell spherical, thin-walled with a closely and rather coarsely apparently granular surface and a variable number of radially arranged appendages which approximate in length to the radius of the shell. A "marginal zone" often present, given the impression that the shell is thick-walled, is, in fact, due to compression.
Original description: Cookson and Eisenack, 1967, p.253: Baltisphaeridium septatum
The appendages vary in size, shape and structure. The majority narrow somewhat from a broadened base and divide distally into two or three straight or curved tapering branches with closed, pointed or minutely bifurcate tips. The larger appendages are typically hollow and septate throughout; in the finer to thread-like ones, on the contrary the degree of septation is often difficult to determine and their distal portions, at least, appear to be solid. A few of the appendages are unbranched. A pylome has been seen in a few specimens.
Dimensions: Holotype: overall diameter c. 80 µm diameter of shell c. 57 µm, appendages 10 - 18 µm long. Range: shell diameter c. 42 - 58 µm.