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Downiesphaeridium tribuliferum
From Fensome et al., 2019:
Downiesphaeridium tribuliferum (Sarjeant, 1962a, p.487, pl.70, fig.4; text-figs.6c,7) Masure in Fauconnier and Masure, 2004, p.196). Holotype: Sarjeant, 1962a, pl.70, fig.4; Fauconnier and Masure, 2004, pl.23, fig.11. Originally Baltisphaeridium (Appendix A), subsequently Cleistosphaeridium, thirdly Cleistosphaeridium?, fourthly Impletosphaeridium, fifthly (and now) Downiesphaeridium. Age: Oxfordian.
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Original description: [Sarjeant, 1962a]:
Baltisphaeridium tribuliferum sp. nov.
Plate 70, fig. 4; text-figs. 6c, 7
Holotype. M134/2/29, 62-foot horizon of Ampthill Clay, Melton.
Dimensions of type. Overall: long diameter 59 u, short diameter 54 u. Shell: long diameter 33 μ, short diameter 25-5 μ. Range of dimensions. Overall: long diameters 53-62 μ, short diameters 48-58 μ.
Diagnosis. A species of Baltisphaeridium having an ovoid shell bearing widely spaced processes, attached proximally by root-like extensions on the shell surface and tapering somewhat distally, branching at a constant distance from the shell surface into bi-, tri- or quadri-furcations of variable length and attitude.
Description. Shell smooth, without granulation or punctation, varying in hue from yellowish to quite colourless. The spines are hollow but appear not to open directly into the shell's interior. They are of very variable form, never simple but having two to four branches of varying length: the branches appear flexible and may be directed outward from, or inward towards, the shell surface or may be roughly parallel to it (text-fig. 7). The branches are closed at their tips. The spines are widely spaced: the number present is between about forty-five and sixty; in length they exceed half the long diameter.
Remarks. Baltisphaeridium tribuliferum differs from all described species of this genus in its combination of form, and proportionate length, of processes with shell shape. The forms from the Lower Oxfordian of France, described by Deflandre as Hystrichosphaeridium cf. intermedium (1938), are probably attributable to this species, as also is the form from the Bathonian of France, described under this name by Valensi (1953).
This species is present in low numbers at three Melton horizons and has also been noted from all three horizons of the Yorkshire Oxford Clay (see above) and from the Lower Calcareous Grit and Hambleton Oolite of Filey Brigg, Yorkshire.
Downiesphaeridium tribuliferum (Sarjeant, 1962a, p.487, pl.70, fig.4; text-figs.6c,7) Masure in Fauconnier and Masure, 2004, p.196). Holotype: Sarjeant, 1962a, pl.70, fig.4; Fauconnier and Masure, 2004, pl.23, fig.11. Originally Baltisphaeridium (Appendix A), subsequently Cleistosphaeridium, thirdly Cleistosphaeridium?, fourthly Impletosphaeridium, fifthly (and now) Downiesphaeridium. Age: Oxfordian.
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Original description: [Sarjeant, 1962a]:
Baltisphaeridium tribuliferum sp. nov.
Plate 70, fig. 4; text-figs. 6c, 7
Holotype. M134/2/29, 62-foot horizon of Ampthill Clay, Melton.
Dimensions of type. Overall: long diameter 59 u, short diameter 54 u. Shell: long diameter 33 μ, short diameter 25-5 μ. Range of dimensions. Overall: long diameters 53-62 μ, short diameters 48-58 μ.
Diagnosis. A species of Baltisphaeridium having an ovoid shell bearing widely spaced processes, attached proximally by root-like extensions on the shell surface and tapering somewhat distally, branching at a constant distance from the shell surface into bi-, tri- or quadri-furcations of variable length and attitude.
Description. Shell smooth, without granulation or punctation, varying in hue from yellowish to quite colourless. The spines are hollow but appear not to open directly into the shell's interior. They are of very variable form, never simple but having two to four branches of varying length: the branches appear flexible and may be directed outward from, or inward towards, the shell surface or may be roughly parallel to it (text-fig. 7). The branches are closed at their tips. The spines are widely spaced: the number present is between about forty-five and sixty; in length they exceed half the long diameter.
Remarks. Baltisphaeridium tribuliferum differs from all described species of this genus in its combination of form, and proportionate length, of processes with shell shape. The forms from the Lower Oxfordian of France, described by Deflandre as Hystrichosphaeridium cf. intermedium (1938), are probably attributable to this species, as also is the form from the Bathonian of France, described under this name by Valensi (1953).
This species is present in low numbers at three Melton horizons and has also been noted from all three horizons of the Yorkshire Oxford Clay (see above) and from the Lower Calcareous Grit and Hambleton Oolite of Filey Brigg, Yorkshire.