Nematoplexus branch
knot close-up
The
so-called branch
knots related to Nematoplexus
in a still obscure way have been
considered in a previous contribution with several examples, among
them rare big ones: Rhynie
Chert News 126.
Another one of the more common type will be presented here with higher
magnification (Figs.1,2).
Fig.1: Nematoplexus:
sparsely scattered tube
fragments with right-handed thread, dark branch knot apparently
detached.
Image width 1mm.
The pale or dark fragments of wound tubes in Fig.1 (tube diameter
about 12µm, thread diameter
100-130µm) fit well into the majority of the tubes compiled in the
diagram of spiral tube
sizes in Rhynie
Chert News 122.
Most conspicuous are the different tube sizes
apparent in Fig.2. One
tube of 12µm had been torn off so that only a stump is left
below
right. A tube of the same size is very faintly seen in the corner above
right and only slightly more distinctly in Fig.1.
Fig.2: Nematoplexus
branch
knot from Fig.1, showing largely differing tube diameters.
Image width 0.15mm. Photograph
by Gerd
Schmahl.
As usual with Nematoplexus,
the internal structure of the knot is not revealed even with higher
magnification. The tubes of 4µm diameter sticking out on the left do
not justify the assumption that there are lots of them inside. One
recurved tube seen on the left seems to indicate that these tubes tend
to keep near the knot.
What seems to be another type of tubes,
diameter 2µm or less, extend right away from the knot. One is faintly
seen in Fig.2 turning towards the right edge, and another one, hardly
seen, towards the upper edge of the image.
Sample:
Rh14/35 (0.17kg), Part 1, found in 2015.
Considering that Nematoplexus
has turned out to be more complex than previously assumed [1],
further investigations with adequate magnification are expected to
provide information which should help to find a place on
the Tree of Life for this
enigmatic organism .
H.-J. Weiss
2018
[1] A.G.
Lyon: On the fragmentary remains of an organism referable
to the nematophytales, Nematoplexus rhyniensis.
Trans. Roy. Soc. Edinburgh
65(1961-62), 79-87, 2 plates.
(Scale error on Plate I Fig.1: not x19
but x1.8)
 |
 |
133 |