|species arranged in stratigraphic order, youngest at top (time control age-window is: 0-800Ma)|
|S. heteromorphus & variants|
Apical spine very well-developed. Lateral elements nearly as large as proximal elements.
Large; proximal shield wide and high; apical spine slightly extended & made up of a single crystal unit
Transitional to S. milanetti - base well-eveloped, convex lower surface, shouldered profile.
Dart-shaped, apical spine well-developed. Lateral elements much smaller than proximal elements.
Similar to S. heteromorphus but base has more elements including a few almost parallel with the spine; spine slightly asymmetric
Large, coarsely constructed with high, gently tapering base and short tapering spine that is dark at 0° and bright at 45°.
Small sphenolith with long apical spine and compact base.
|S. delphix and variants|
Large (>8µm) sphenolith with single long apical spine and flaring proximal cycle.
Like S. delphix, but smaller (<8 µm)
Like S. delphix, but smaller (<8 µm) and with short spine
Distinguishing features: Late Oligocene - Early Miocene sphenoliths with apical spines formed from a single element.
Farinacci & Howe catalog pages:
Morphology: The spines go into extinction as a single unit when they are aligned with the polarisation directions
|Metrics||Lith size: 4->20µm;|
Notes: S. heteromorphus and S. belemnos are common species and key biostratigraphic markers. S. delphix, S. capricornutus and S. calyculus are a group of relatively rare small species with well-developed apical spines characteristic of the Earliest Miocene.
Last occurrence (top): near base of Serravallian Stage (13% up, 13.5Ma, in Serravallian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Rupelian Stage (74% up, 29.6Ma, in Rupelian stage). Data source: Total of range of species in this database
Plot of occurrence data:
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