S. heteromorphus group


Classification: Coccolithophores -> Discoasterales -> Sphenolithaceae -> Sphenolithus -> S. heteromorphus group
Sister taxa: S. capricornutus group, S. dissimilis group, S. moriformis group, S. heteromorphus group, S. predistentus group, S. furcatolithoides group, S. radians group, S. conspicuus group, S. sp.,

Daughter taxa: species arranged in stratigraphic order, youngest at top (blue => in age window 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.
S. belemnos
Dart-shaped, apical spine well-developed. Lateral elements much smaller than proximal elements.
earlier species
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

Taxonomy:

Citation: Sphenolithus heteromorphus group
Rank: species group

Distinguishing features: Late Oligocene - Early Miocene sphenoliths with apical spines formed from a single element.

Farinacci & Howe catalog pages:


Morphology remarks: The spines go into extinction as a single unit when they are aligned with the polarisation directions

Search data:
TagsLITHS: N: 3D-radiate, conical, RIM: tiered, PROCESS: length-fast, monocrystalline, spine,
CSPH: not known, V-UNITS: spine, R-UNITS: lower-tier, middle-tier, DETAILS: isogyres radial,
MetricsLith size: 4->20µm;
Sources:
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
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:

References:


nannotaxlogo400px

S. heteromorphus group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 15-7-2020

Taxon Search:
Advanced Search

Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=1214 Go to Archive.is to create a permanent copy of this page - citation notes



Comments (0)

No comments yet on this page. Please do add comments if you spot any problems, or have information to share

Add Comment

* Required information
1000
Captcha Image
Powered by Commentics