One piece of petrified wood challenging the "state of the science"
deutsche Version

Dark clots like those in Fig.1 have been found in petrified wood worldwide and interpreted as coprolites of small creatures in numerous publications. Remains of creatures of fitting size have never been seen near the clots. Nevertheless the imaginary creatures have been specified in [1] and previous publications as oribatid mites, also more cautiously as "unknown creatures" [2] or "new detritivores" [3].

cell-size clots in woodFig.1: Silicified wood, cross-section, one radial row of tracheids partially replaced by dark clots.
Lower Permian, Schallodenbach, Rhine-Palatinate. Width of the picture 1.4mm.

Fig.1 illustrates one of several reasons for doubt concerning the current interpretation: No creature would have been able to neatly gnaw off a row of wood cells and replace them with same-size coprolites. Doubts of this kind were ignored by the proponents of the coprolite hypothesis since 2007.
For lack of reasonable arguments, R. Rößler, author and co-author of numerous publications on the alleged coprolites, involved a lawyer to declare the coprolite interpretation of dark clots as the current "state of the science". To think of this ! Those who shy away from discussions try to define the "state of the science"!  This is contrary to the very principles of science and therefore cannot be kept up for long. So it is not really surprising that it takes only one image of petrified wood (Fig.2) to show how the clots are formed and
to expose the coprolite interpretation as nonsense.
(The other images are for additional substantiation. All images are of the same scale. They show the polished face of a sample cut off from a larger find kindly provided by Ch. Krüger, Schallodenbach. It is kept in the own collection under Sch/3.1. The larger part has been returned.)

Fig.2 (below): Silicified wood with pale clots inside cells seen to be evolving into dark clots in destroyed tissue: wood rot in progression. Width of the picture 1.4mm.

clots forming in woodFig.2 indicates that pale clots originate within the apparently empty cells and
grow darker. This reveals the  succession of events: Mechanical damage of the wood favouring the onset of rot beginning with pale clots in the cells near the fracture face, proceeding with the decay of cell walls and darkening and eventual expansion of the clots. The same occurred at several places within this sample, see Fig.3.

Fig.3 (below): Wood rot in progression (upwards in this image). Width of the picture 1.4mm.
clt formation in woodApparently the partial processes mentioned above are not always coupled: Pale clots may accumulate in large numbers without turning dark (also in this sample but not shown here), and dark clots may be found in parts of tissue without damaged cell walls (Figs.3,4). This implies that dark clots have not always expanded beyond cell size (Figs.3-5).
clots in wood cells
Fig.4 (far right): Dark clots in well-preserved tissue. An interpretation as coprolites is obviously excluded for several reasons. Width of the picture 0.25mm.
 
angular clots in pith cellsIt be mentioned here that clots of this origin are seen not only as globules within cells or among damaged tissue but also as angular replicas of the cell lumina as in Fig.5., where the dark matter apparently has filled the cell completely and kept this shape after the decay of the cell walls. Sometimes such replicas are the only structural information left of the vanished tissue, as in the present case. Even angular cell-size clots have repeatedly been mistaken for coprolites [4].

Fig.5: Angular replicas of pith cells with polygonal cross-sections: only evidence of the former tissue structure of the decayed central pith. Width 0.4mm.

The above pictures taken from one sample which is representative of all silicified wood with cell-size clots lead to the following conclusions:
(1) Every dark clot grew from a pale clot within a cell.
(2) The clots represent a kind of wood rot which can destroy the tissue.
(3) After decay of the cell wall the clots can expand and displace themselves so that the wood structure gets lost.
(4) Cell-size clots in silicified wood, arranged in rows or at random, have lightly been interpreted as coprolites.
(5) The interpretation as coprolites in all related publications, including [1-4], is utterly wrong.

H.-J. Weiss     2015

[1]  Z. Feng, J.W. Schneider, C.C. Labandeira, R. Kretzschmar, R. Rößler:
      A specialized feeding habit of Early Permian oribatid mites.
      Palaeogeography, Palaeoclimatology, Palaeoecology 417(2015), 121-124.

[2]   M. Barthel, M. Krings, R. Rößler: Die schwarzen Psaronien von Manebach, ihre Epiphyten, Parasiten und Pilze. Semana 25(2010), 41-60.
[3]  Zhuo Feng, Jun Wang, Lu-Yun Liu,  R. Rößler:
      A novel coniferous tree trunk with septate pith ..: -  Ecological and evolutionary significance.
      Int. J. Plant Sci. 173(2012), 835–848.

[4]  R. Rössler: The late palaeozoic tree fern Psaronius  -  an ecosystem unto itself.
      Rev. Palaeobot. Palyn. 108(2000), 55-74.
quartz crystal with wood inside
Fossil Wood News 26

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