Cell-size clots in fossil wood --- no coprolites
deutsche Version

Cell-size clots in fossil wood are the results of some process which requires an explanation. As a favourite explanation found in many publications worldwide, small arthropods are thought to have gnawn tunnels or galleries through the tissue. They were never seen but dark clots interpreted as coprolites were taken as evidence for their temporal presence.
Those interpretations are fraught with glaring discrepancies which none of the authors seemed to have noticed: The alleged mite coprolites are often angular, with edges and plane side faces like the inside of the nearby cells. Hence they are no coprolites but clots grown inside cells.
angular clots in Psaronius empty and filled Psaronius root cellsangular clots in wood clots inside and outside wood cells
Fig.1: Alleged mite coprolites [1] but really clots shaped like cells.
Fig.2: Psaronius root cells [2] empty or with black fill.
Fig.3: Coniferous wood tissue allegedly damaged by mites [3]; no coprolites but cell-size clots.
Fig.4: Similar as Fig.3; round clots growing within cells in rows and finally getting out [4].
bugs in tree fern
As a big surprise after much vain talk by experts about mite coprolites without mites, the fossil collector Gert Müller, carpenter by profession, seems to have found the elusive arthropods in their burrows in plant tissue preserved in chert (Fig.5) but nothing in this picture looks like coprolites fitting to the creatures.
Incidentally, G. Müller had been the first one to raise severe doubts about the alleged mite coprolites in [2].

Fig.5: Juvenile (?) arthropods in degraded tree fern tissue in Lower Permian chert, Döhlen basin, Saxony.
Width of the picture about 3mm. Sample and photograph by Gert Müller

The authors of the numerous publications involving alleged oribatid mite coprolites in fossil wood did not see what could be seen in a few pictures like these ones: The cell-size clots offered as mite coprolites are no such. This had been explained as early as 2007 [6] and repeatedly afterwards.
In a new publication [7] on an old sample [2], proponents of the coprolite hypothesis tacitly admitted their error as late as 2017 by simply not mentioning the alleged coprolites any more. This implies the question what the clots could be if not coprolites. The answer can be found in publications on Early Land Plants from the Devonian which are frequently infested with the fungus Glomites. The tiny hyphae of that fungus form dense tangles appearing as dark clots inside cells, and they can spread to neighbouring cells [8]. Apparently some fungus had produced the clots in fossil wood, too.
Considering that the authors R. Rößler and Z. Feng are responsible for erroneous publications on arthropod coprolites for decades, the recent publication [9] should be regarded with suspicion.
H.-J. Weiss    2023

[1]   R. Rößler: The late palaeozoic tree fern Psaronius - an ecosystem unto itself. Rev. Palaeobot. Palyn. 108(2000), 55-74.
[2]  M. Barthel, M. Krings, R. Rößler: Die schwarzen Psaronien von Manebach, ihre Epiphyten, Parasiten und Pilze. Semana 25(2010), 41-60.
[3]   R. Rößler, R. Kretzschmar, Z. Feng, R. Noll: Fraßgalerien von Mikroarthropoden in Konifernhölzern des frühen Perms von Crock, Thüringen.
     Veröff. Mus. Naturkunde Chemnitz 37(2014), 55-66.
[4]   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.
[5]   Gert Müller: private communication.
[6]  H.-J. Weiss: 6. Chert Workshop 2007, Naturkunde-Museum Chemnitz.
[7]  M. Krings, C.J. Harper, J.F. White, M. Barthel, J. Heinrichs, E.L. Taylor, T.N. Taylor: Fungi in a Psaronius root mantle from the Rotliegend (Lower Permian) of Thuringia,
     Rev. Pal. Pal. 239 (2017), 14-30.
[8]  H. Kerp: De Onder-Devonische Rhynie Chert ... . Grondboor & Hamer 58(2004), 33-50.
[9]   Z. Feng, M. Bertling, R. Noll, A. Slipinski, R. Rößler: Beetle borings in wood with host response in early Permian conifers from Germany, Paläontol. Z. (July 2019).

quartz crystal with wood inside
Fossil Wood News 45
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