Nannotax Enabling nannofossil research

Description: Sphenoliths without prominent apical spines.

Species included:

Typical specimens	Outline description	Range
	S. abies - cuspate outline, with apical elements elongated into compound spine	caNN7 - NN15
	S. conicus - with small apical spine	Oligocene - NN3
	S.disbelemnos -similar to S. belemnos but with very small apical spine	NN2-3
	S. dissimilis - similar to S. moriformis but with apical cycle of elements extended to form circlet of spines	Oligocene - NN3
	S. moriformis - beehive shaped	Eocene - NN10

Species in this group are poorly defined and of very limited biostratigraphic value. A number of additional species were described by Maiorano & Monechi (1997, 1998) from the Early Miocene:

The following genera of nannoliths (or modified heterococcoliths) are
not currently assigned to any family, reflecting the uncertainty in
their affinities. They are clasified here in the  incertae sedis

• Sphenolithus milanetti Maiorano and Monechi, 1998
• Sphenolithus multispinatus Maiorano and Monechi, 1997
• Sphenolithus procerus Maiorano and Monechi, 1997
• Sphenolithus tintinnabulum Maiorano and Monechi, 1997