A miniature football from the Rhynie chert
deutsche Version

charophyte whorl base
What looks here like a ball stitched together from polygonal patches is really a solid sphere made of tightly fitting polyhedral alga cells. It serves as the base of a whorl of charophyte branches.
The polyhedral cells differ strongly from the big tube-like cells of the branches. A few of the possibly 7 branches of this whorl vanish in the depth of the picture, hence Fig.1 is a tilted view from below. Apparently the stem bearing the whorl has been cut off, thus is not seen here.

Fig.1: Multicellular globular base, 
0.24mm, of a charophyte whorl with branches
         consisting of big cells, seen on a cut face
of a chert sample. Image height 1mm.

Of the charophyte algae in the Rhynie chert it is known that their stem and branch segments consist of only one cell, like with extant Nitella, after which the name Palaeonitella had been coined [1]. As pointed out before [2], this might not have been an apt choice because some or even all of the algae called 
Palaeonitella are wide apart from Nitella and all known charophytes in a phylogenetic sense. (See also Rhynie Chert News 93 .)
The ball in Fig.1 is not a unique phenomenon. There are more of such but less beautiful ones, as in Figs.2,3 (same scale as Fig.1).
charphyte whorl section
Fig.2 (left): Charophyte whorl base exposed as a cross-section, seen from belowon the raw sample surface.
Image 0.65mm.


Fig.3 (below):
Multicellular base of a charophyte whorl as seen just below the raw sample surface, poorly preserved, no branches left.
Image height 0.25mm.

charophyte whorl base

Similar as with Fig.1, the well-preserved branches of the whorl seen from below in Fig.2 are directed upward (into the picture plane). The segmentation of the globule is faintly indicated.
Despite of the missing branches in Fig.3, this object, too, is doubtless a charophyte whorl base.
These globules do not seem to be compatible with the detailed images of whorl bases in [3].

All pictures have been taken from a chert sample of 0.28kg found in 2003, labelled Rh9/86.


H.-J. Weiss
   2018

[1]  R. Kidston, W.H. Lang: On Old Red Sandstone plants … Part V,
    Trans. Roy. Soc. Edinburgh 52(1921), 855-902.
[2]  H.-J. Weiss: First xanthophyte and new charophyte in the Rhynie chert.
    87th Annual Conference of the Paläontologische Gesellschaft, Dresden 2016.
[3]   www.abdn.ac.uk/rhynie
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