Nematophytes 
A brief introduction
deutsche Version
Pachytheca in Rhynie chert The nematophytes, which means "filamentous plants", are known for about 150 years as fossils from the Silurian and Lower Devonian but they are still so poorly understood that lately they are not even listed among plant fossils but more cautiously under "Enigmatic Organisms" [1] (**). Their sizes and shapes range from millimeter-size spheres (Pachytheca, see picture) and centimeter-size flaps (Nematothallus [2], Nematophyton and others, see picture below) to meter-size trunks (Prototaxites) [3].
Essentially they are made up of two or more types of filaments which nearly always appear as empty tubes. The tubes typically form a chaotic tangle (*) with a more or less distinct preference for some plane or direction. In some species, part of the filaments are aligned perpendicular to the surface, most perfectly so in the case of Pachytheca. un-named nematophyte in Rhynie chert


Nematophytes are very rare fossils in the Lower Devonian Rhynie chert but the few specimens found lately provide answers to some of the questions lingering in the literature for a long time. However, they pose new questions, too, as it is apparent from the picture below right.
The
nematophytes from the Rhynie chert represent at least 7 species, among them non-described ones. The tubes of the live nematophytes seem to have been embedded in gel.
The long-standing enigma of an unexpected cellular pattern known as Nematothallus cuticle, often found together with coalified tangles of filaments, is demystified here for the first time. Uncommon Nematoplexus "branch knot"

The much bigger enigma of Prototaxites has aroused the imagination of scientists as well as fossil collectors, giving rise to wild speculations ever since it was discovered up to now (2010). The latest attempt to demystify the great Prototaxites by assorting it with humble liverworts is thwarted here with the help of small nematophytes from the Rhynie chert.
Most of the discoveries and conclusions discussed in the contributions up to Nr. 41 had been presented at EPPC 2010 [4].

*
On the Aberdeen Univerity website [5], the characteristic feature of Nematoplexus, the spirally wound tubes, is ascribed to virtually all nematophytes. Apparently they did not know Pachytheca with straight tubes and other nematophytes with irregularly wavy tubes, as in the image above.
** Also in [1], chapter on bryophytes, it is proclaimed that "One interesting hypothesis suggests that several of the enigmatic ... nematophytes may represent remains of ancient liverworts ... . ... At least some of the tubular aggregations assigned to nematophytes have been reinterpreted as ... liverwort rhizoids, ... ." That hypothesis is refuted in
Rhynie Chert News 41.
For new developments see [6] and the discussion in Rhynie Chert News 30.

Contribution                 Subject
Rhynie Chert News   1     Pachytheca, first specimen in chert, central cut
Rhynie Chert News 13     weft of big tubes, new species ?
Rhynie Chert News 29     Nematoplexus, big variety,
new species ?
Rhynie Chert News 30     pseudo-cells ("Nematothallus cuticle") explained
Rhynie Chert News 35     flat nematophyte, 
Nematophyton taiti (?)
Rhynie Chert News 36     Pachytheca, first specimen in chert, off-centre cut
Rhynie Chert News 38     no liverwort connection of nematophytes and Prototaxites
Rhynie Chert News 39     Nematoplexus with a wry twist ?
Rhynie Chert News 40 
     shrunken tubes
Rhynie Chert News 41     no liverwort connection of Cosmochlaina and Prototaxites 
Rhynie Chert News 44      Pachytheca – a nematophyte propagule ?
Rhynie Chert News 46     Nematophyton taiti (?)   details and reconstruction
Rhynie Chert News 51     Nematoplexus aspects
Rhynie Chert News 71     Nematoplexus - more details, more questions (1)
Rhynie Chert News 86     tangle of very thin tubes, 6-8Ám
Rhynie Chert News 92     glades in the weft of big tubes
Rhynie Chert News 98     weft of big tubes in a gel lump with dried-up surface layer
Rhynie Chert News 99      weft of narrow tubes with peculiar details
Rhynie Chert News 102     Nematoplexus - more details, more questions (2)
Rhynie Chert News 106    Nematoplexus big and small, new charophyte gametangia, Castracollis
Rhynie Chert News
107    first 3D-Nematothallus


H.-J. Weiss          updated 2016, 2017  

[1] T.N. Taylor, E.L.Taylor, M. Krings: Paleobotany, Elsevier 2009.
[2]  P. K. Strother: Clarification of the genus Nematothallus, J. Paleont. 67 (1993), 1090-94.
[3]  H. Steur: http://www.xs4all.nl/~steurh/
[4]  H.-J. Weiss: Enigmatic Organisms  -  Insights derived from new finds, Poster presentation, EPPC Budapest 2010.
[5]  www.abdn.ac.uk/rhynie/nemato.htm
[6]  M.R. Smith, N.J. Butterfield:  A new view on Nematothallus: Coralline Red Algae from the Silurian of Gotland.
      Palaeontology 56(2013), 345–357.


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