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Fourier shape analysis of Upper Cretaceous Normapolles from southern Sweden

 

作者: StefanU. Hultberg,   BjörnA. Malmgren,   Annie Skarby,  

 

期刊: Grana  (Taylor Available online 1984)
卷期: Volume 23, issue 2  

页码: 97-107

 

ISSN:0017-3134

 

年代: 1984

 

DOI:10.1080/00173138409428884

 

出版商: Taylor & Francis Group

 

数据来源: Taylor

 

摘要:

Pollen grains of three previously described species of Upper Cretaceous dispersed Normapolles from souther Sweden,Extratriporopollenites (Oculopollis) tricepsSkarby,E. (Trudopollis) artifexWeyland & Krieger andE. (Trudopollis) firmusSkarby, and specimens extracted from a single anther (identified asE. artifex), have been analyzed by Fourier analysis. The purpose was to assess quantitatively the diagnostic significance of the outer and inner equatorial contour, and also the validity of the species. Seventy-two radii were measured at equal angular increments along the outer and inner contour, and Fourier series were fitted to the resulting curves. The shapes of the pollen grains may be described by the average radius (zeroth harmonic) and a series of cosine curves relating to their three-fold symmetry (third, sixth, nineth through twenty-fourth harmonic). Multivariate analyses of these harmonics show thatE. firmus, which lacks prominent apertures, stands out as a distinct species. The specimens from the single anther fall within the range ofT. artifex. Some specimens identified asE. tricepsoverlap withT. artifex, indicating that the apertures in this species, described as well-developed, may approach the less prominent apertures ofT. artifex. The results emphasize the difficulties in separating the generaOculopollisandTrudopollisPflug. Typical specimens can be identified, but not intermediate forms. In order to solve this problem a thorough quantitative analysis of dispersed specimens and pollen from anthers is necessary.

 

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