Early Miocene (3)
Discoaster (12)
Sphenolithus (20)
Helicosphaera (14)
Rhomboasteraceae Bown, 2005
Description: Nannoliths with rhombic and tri-radiate morphologies, and non-birefringent images in XPL. Incorporating the genera Rhomboaster and Tribrachiatus.
Remarks:
Paleogene: Rhomboasteraceae