|Daughter taxa (time control age-window is: 0-800Ma)|
|species here provisionally placed in Planohetorohelix|
Specimens which cannot be assigned to established species
Original description: Description. Test is biserial throughout. Proloculus is small and followed by larger second chamber. Chambers are subglobular to globular in early portion of test and often reniform in adult. Periphery is broadly rounded. Aperture is a low- to medium-high arch situated at base of last-formed chamber; it is bordered by two symmetrically developed flanges. Chamber surface is smooth or with fine longitudinal costae in earlier species and completely costate in evolved ones. Test wall is calcitic, hyaline, microperforate to finely perforate. Pores are situated in intercostal spaces or they might penetrate and interrupt costae.
Entries in the Catalog of original descriptions: Planoheterohelix, Globoheterohelix
Parent taxon (Heterohelicidae): Aperture symmetrical, ranging from a low slit to a high arch at the base of the final chamber, becoming terminal in uniserial taxa.
This taxon: Biserial throughout, aperture symmetrically positioned, wall texture costate.
Last occurrence (top): near top of Maastrichtian Stage (94% up, 66.4Ma, in Maastrichtian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Cenomanian Stage (67% up, 96.1Ma, in Cenomanian stage). Data source: Total of range of species in this database
Plot of range and occurrence data:
Planoheterohelix compiled by the pforams@mikrotax project team viewed: 27-1-2023
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