Back
Polystephanephorus euryanthus
Polystephanephorus euryanthus Cookson and Eisenack, 1974
Holotype: Cookson and Eisenack, 1974, pl.24, fig.14; Fauconnier and Masure, 2004, pl.65, fig.4.
Age: ?Neocomian-Albian
Original diagnosis: Cookson and Eisenack, 1974, p.70-71
Central shell spherical, fairly thick-walled, bearing approximately 20 (up to 24?) radially extending processes. These are not quite uniformly distributed and are also not of equal lengths. Toward the one side they are less densely arranged and are longer (about 33 µm), whereas toward the other side they are closer crowded together and are shorter (about 24 µm). They start with a hollow, cylindrical foundation, which becomes slightly broader, the base and from there sends forth short radial-lists to the shell. The diameter of these cylinders varies (compare with statements made under dimensions). Approximately half way up, at times already before, the cylinder breaks up into diverging branches, the fine acuminate extremities of which can become connected with one another, as well as also with those of the adjacent processes. These inter-branchings and the anastomoses are quite irregular.
Overall, a complicated ornamentation is created and the spherical shell, most probably, had been surrounded at the level of the process-extremities by a reticulation which, although of a loose nature was nevertheless a closed reticulation.
The cylindrical lower extremities of the processes are distinctly granular and this granulation also extends upwardly onto the branchings.
An injury of the central shell allows one to recognize that it has a laminated structure and that each, approximately hexagon plate, bears a process.
Number of available specimens and dimensions: One specimen. Diameter of central shell about 67 µm, overall about 118-120 µm length of processes about 24-33 µm; projection of individual processes up to 54 µm, breadth of process-bases 3-12 µm.
Age and Occurrence: Omati, Papua (core 21); Aptian - Albian, ?Neocomian.
Remarks: Cookson and Eisenack, 1974, p.71
Owing to the difference of the lengths of the processes, the central shell lies eccentrically within the enveloping peripheral reticulation. This brings to mind cases observed elsewhere as well, such as e.g. in the case of the Hystrichosphaeridium tubiferum. The opening, along the margin of which one recognizes the laminated structure, is viewed by me as an injury and not as an archaeopyle, as it occurs in the case of the Homotryblium. However the fact that only a single specimen is involved here does not allow one to make a decision in this respect.
The species could have also been sub-ordinated to the Cannosphaeropsis, however, the similarity in the construction of the processes with that in the case of the Polystephanephorus urnaforme (Cookson 1953) is unmistakable.
Holotype: Cookson and Eisenack, 1974, pl.24, fig.14; Fauconnier and Masure, 2004, pl.65, fig.4.
Age: ?Neocomian-Albian
Original diagnosis: Cookson and Eisenack, 1974, p.70-71
Central shell spherical, fairly thick-walled, bearing approximately 20 (up to 24?) radially extending processes. These are not quite uniformly distributed and are also not of equal lengths. Toward the one side they are less densely arranged and are longer (about 33 µm), whereas toward the other side they are closer crowded together and are shorter (about 24 µm). They start with a hollow, cylindrical foundation, which becomes slightly broader, the base and from there sends forth short radial-lists to the shell. The diameter of these cylinders varies (compare with statements made under dimensions). Approximately half way up, at times already before, the cylinder breaks up into diverging branches, the fine acuminate extremities of which can become connected with one another, as well as also with those of the adjacent processes. These inter-branchings and the anastomoses are quite irregular.
Overall, a complicated ornamentation is created and the spherical shell, most probably, had been surrounded at the level of the process-extremities by a reticulation which, although of a loose nature was nevertheless a closed reticulation.
The cylindrical lower extremities of the processes are distinctly granular and this granulation also extends upwardly onto the branchings.
An injury of the central shell allows one to recognize that it has a laminated structure and that each, approximately hexagon plate, bears a process.
Number of available specimens and dimensions: One specimen. Diameter of central shell about 67 µm, overall about 118-120 µm length of processes about 24-33 µm; projection of individual processes up to 54 µm, breadth of process-bases 3-12 µm.
Age and Occurrence: Omati, Papua (core 21); Aptian - Albian, ?Neocomian.
Remarks: Cookson and Eisenack, 1974, p.71
Owing to the difference of the lengths of the processes, the central shell lies eccentrically within the enveloping peripheral reticulation. This brings to mind cases observed elsewhere as well, such as e.g. in the case of the Hystrichosphaeridium tubiferum. The opening, along the margin of which one recognizes the laminated structure, is viewed by me as an injury and not as an archaeopyle, as it occurs in the case of the Homotryblium. However the fact that only a single specimen is involved here does not allow one to make a decision in this respect.
The species could have also been sub-ordinated to the Cannosphaeropsis, however, the similarity in the construction of the processes with that in the case of the Polystephanephorus urnaforme (Cookson 1953) is unmistakable.