Daughter taxa (time control age-window is: 0-800Ma)![]() | ||||
![]() | ![]() | ![]() | Sphenolithus cuniculus forms with low basal quadrants (‘feet’) and ~90° bifurcations | |
![]() | ![]() | ![]() | Sphenolithus furcatolithoides Spines diverge just above the base and are near-parallel in the lower part | |
![]() | ![]() | ![]() | ![]() | Sphenolithus kempii square base with 3 or 4 spines |
![]() | ![]() | Sphenolithus perpendicularis square base with two spines that diverge by around 90° | ||
Sphenolithus cf. S. perpendicularis tapering base with narrow, high-angled lateral spines; | ||||
![]() | ![]() | Sphenolithus strigosus duocrystalline spines that bifurcate high-up on the spine. |
Taxonomy:
Distinguishing features: Small Middle Eocene sphenoliths with duocrystaline spines that are dark in the 45° position.
Farinacci & Howe catalog pages:
Morphology: Included within the S. radians group by Bown & Dunkley Jones (2012), these species are characterised by two (rarely more) bifurcating apical spines, bright at 0° and dark at 45°, extending from the upper quadrants. Species differentiation is based on the height and angle of spine bifurcation and size of the basal quadrants. In moderate to poor preservation the upper portion of these tall spines is usually lost, but when well preserved, as seen herein, the entire lith may be preserved, highlighting the extreme spine lengths (up to 25μm; Pl. 11, fig. 25) and variations in upper spine morphology. In the slightly younger, and probably descendant, S. predistentus group, only the lower quadrants are clearly discernable in the basal column and the spines are bright at 45° and diverge in the uppermost part of the spine (e.g. S. obtusus, S. runus, S. predistentus). [Bown & Newsam 2017]
Tags | LITHS: |
Metrics | Lith size: 2->17µm; |
Geological Range:
Last occurrence (top): in lower part of Bartonian Stage (22% up, 40.4Ma, in Bartonian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Lutetian Stage (0% up, 47.8Ma, in Lutetian stage). Data source: Total of range of species in this database
Plot of occurrence data:
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S. furcatolithoides group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 8-3-2021
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=1213 Go to Archive.is to create a permanent copy of this page - citation notes |