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Sphenolithus abies

Edited by Lyndsey on Thu, 10/03/2011 - 12:31

Sphenolithus abies Deflandre in Deflandre and Fert, 1954

Description: typical form is a moderately elevated sphenolith with cuspate outline and with extinction line going dow long axis of spine.

Remarks: Similar to S. moriformis but more elevated and with cuspate outline. Form becomes less distinct with poor preservation. The classic S. abies formis distinctive and does not occur in the Early Miocene but consistent separation from S. moriformis is difficult

6-1abies.JPG 6-2abies.JPG 6-3abies.JPGSab192-25.JPGSab202 (471-2) 02NN14-15.JPGSab203-29 (471-3-29)NN14-15.JPG

Sp abies CP

 

 

Variants:

  • S. grandis Haq and Berggren, 1978 - large form;
  • S. neoabies Bukry and Bramlette, 1969 - small form;
  • S. verensis Backman, 1978 - slight elongations of elements;
  • S. quadrispinatus Perch-Nielsen, 1980 - form with 4 elements elongated into spines, very rare.
Geological Time Data
Geological Time Periods: 
NN15
NN7
Biblio Reference: 
Young, JR.  1998.  Neogene. Calcareous nannofossil biostratigraphy. :225-265.
Notes on occurrence information: 
Questions occur about the beginning of this species' range

Comments

Mon, 07/03/2011 - 14:23 — mstyzen
mstyzen's picture

Sphenolithus verensis

I agree that S. verensis is probably a variant of S. abies (especially considering the very broad original description of S. abies!). The extinction of S. verensis can be a useful marker. The diagnosis for S. verensis is a little more complex than what is stated above. In the forms I refer to S. verensis the apical spine is extinct when paralell to the crossed nicols. leaving a dark V shape where the spine is. The basal spines are usually somewhat longer in well preserved specimens and sometimes they appear to be at a more oblique angle to the long axis.

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