Wilting nematophytes in Rhynie chert
literally "filamentous plants", are still so poorly
understood that they go under the heading Enigmatic Organisms in .
Therefore, any newly observed detail is potentially relevant and worth
There are not many details seen in the small nematophytes usually
preserved as coaly compressions . 3D-preservation in chert provides
the possibility to see more. Several insights have already been
obtained from the very few nematophyte specimens found in the Rhynie
hitherto, see Rhynie
Chert News 1, 13, 29, 30, 35, 36, 38, 39.
are presented in the following.
The filaments of the nematophytes appear mostly as empty tubes, as in
Fig.1. One may ask whether it is really tubes what is seen here or
merely the tube-shaped cavities left after the organism had decayed and
vanished, together with its tube, after silicification of the space
between them. The aspect of the tubes suggests that there are remains
substance left in the chert sample.
Fig.1: Nematophyte tubes in Rhynie chert,
A kinked tube (above left) allows conclusions to be drawn concerning
mechanical properties of the wall material.
Width of the picture 1.75mm.
of whether or not there is wall substance left in Fig.1, one can derive
information on the mechanical properties of the tubes before
silicification. One tube (above left) got a kink when it was bent by
contact with others. Hence, it must have consisted of a material with
some flexibility and strength. If it had been more brittle, or soft and
weak, it would have broken or torn. Also the kink serves as evidence
that there was a tube wall at all, which excludes the possibility of a
spaghetti-like filament without wall.
Nematophyte, non-described species in Rhynie chert; tubes well aligned,
cross-sections up to 70Ám, smaller ones inside indicating shrinkage.
The smaller cross-sections seen inside some of the "normal" ones in
Figs.2,3 pose a problem. They could possibly be degraded and shrunken
tubes within the cavities in the silica gel preserving the size of the
original tubes. (Such phenomenon is known from fossil plants, see Rhynie
Chert News 31.)
However, there are a few details, as the gap in a ring in Fig.3, which
are not yet understood.
A different possibility has to be considered: The smaller section may
not be the shrunken tube but the cell plasma with enclosing membrane
away from the tube wall.
The question remains why the phenomenon is restricted to some of the
tubes in some part of the specimen. A possible answer may also apply to
Fig.4: For reasons unknown, silicification was not equally fast
throughout the sample so that various stages of the succession of decay
have become preserved.
In the sample region seen in Fig.4, right, silicification seems to have
been so slow that the organic gel keeping the tubes together in a lump
Chert News 30)
decayed before it could turn into silica
gel. As a result, the tubes apparently
shrunk, dispersed and became
Fig.4 (right): Nematophyte in Rhynie chert, same
as Figs.2,3, tubes up to 70Ám across
and big "branch knots",
transition region between well preserved dark tubes and shrunk,
dispersed, and bleached ones.
The two conspicuous lumps, and perhaps a smaller third one above left,
are a typical feature of nematophytes, called branch knots. They
consist of a tangle of much smaller tubes and seem to be somehow
related to the big ones, too. Their function, like the organism as a whole, is still enigmatic.
2016: Closer inspection has shown that the big clots seen here do not
consist of a tangle of tubes and therefore differ from the "branch
knots" known from other nematophytes. See Rhynie
Chert News 92,)
What is seen inside a few tubes in Fig. 5 seems to be the tube content
shrunken into a narrow crumpled filament. Possibly these tubes were
"dead" before silicification, and the "live" tubes became silicified in
such a way that they look empty now.
Nematophyte tubes in Rhynie chert, same specimen as in Fig.1.
Note the dark filament in some of the tubes. Width of the
Similar crumpled filaments inside tubes are found in Pachytheca from
Lac de la Gileppe . They have not been seen in Pachytheca from
Chert News 1, 36).
Also remarkable in Fig.5 is one of the seldom seen branching
sites. (2016: probably no branching.)
H.-J. Weiss 2011, 2016
T.N. Taylor, E.L. Taylor, M. Krings:
 P. K. Strother:
Clarification of the genus Nematothallus,
J. Paleont. 67 (1993),
Gerienne: Les Pachytheca
de la Gileppe ...
Geol. Belgique 113(1990), 267-285.