Comment on: The Late Palaeozoic tree fern Psaronius ... by R. Rössler [1]
deutsche Version

The subject of that paper, the intimate connection of Permian tree ferns with the ecosystem, is doubtless an interesting one, and thus the paper, too, had been destined to become interesting. The comment does not concern this aspect of the matter but the tangle of minor inconsistencies due to superficiality and the more serious indications of questionable judgement, unseen at first sight but emerging clearly with closer inspection, having escaped the notice of the reviewers and numerous palaeobotanists whose "critical and stimulating discussions" are acknowledged in the paper.
From the aspect of the Ankyropteris cross-sections in Plate VII one can already guess that the magnification data are mutually incompatible. With some effort one can find data which hopefully will lead near
the real sizes. One can make use of the fact that the same pictures have been published by R. Rössler several times, with variation in scale, orientation, frame boundary, and also as mirror images. As an additional difficulty, the modified images, too, come with contradictory size data, which delays but does not prevent comparison. Clots misinterpreted as coprolites, Permian, Chemnitz

Fig.1: Angular clots in the tissue of the climbing fern Ankyropteris brongniartii, detail from [1], Plate VII4, Lower Permian, Chemnitz.

Provided that one can trust the magnification given as 6x for Fig.334 in [2], one can conclude from Fig.336, which is the mirror image of a detail of Fig.334 and is also the same as Plate VII5 in [1] turned around by 135°, that 35x instead of 14x is the proper magnification number for Plate VII5, after correcting the scale of Fig.336 by a factor of 2 which is evident from comparison with Fig.334.
Minor size differences up to 30% become apparent by comparing the figures on Plates III, IV, VI in [1] with those in [2] and [3].

Fig.336 in [2] is said to show a detail from the main axis of Ankyropteris in Fig.334. There is no such detail on the main axis. The detail is found on the frond stalk. The same error is present in [1], caption to Plate VII5. (Here, the meaning of "Ankyropteris marginal axis" is not immediately obvious but from Fig.334 in [2] it can be deduced that it means a main axis of the climbing fern which is not completely enclosed within the Psaronius trunk.)
angular clots in fossil plant, no coprolites
Fig 2: Cell-size angular clots in Ankyropteris, arranged in files on the left, detail from [1], Plate VII2.

Plate VII3-5 shows details of a thin slab pictured in a paper by Sterzel [4], who was careful enough to refrain from an interpretation of the tiny dark clots seen in these pictures. Along with such clots in Callistophyton (Plate VI), they are interpreted in [1] as arthropod coprolites: "Two distinct size orders of the coprolites indicate coexistence of different arthropods or different ontogenetic stages ..."
The interpretation of these and other cell-size clots is specified as oribatid mite coprolites in [2,3].

Fig.3 (right): Angular clots of various sizes in Ankyropteris, detail from [2], Fig.335 below right, (which is the mirror image of Plate VII4 in [1]). Note the cell above right with a clot of corresponding shape inside.
angular clots in Ankyropteris, no coprolites

The publications [1-3] are obviously influenced by the notion of Palaeozoic oribatid mite coprolites which had spread among palaeobotanists in the 1990s, apparently by adopting without checking, even though no oribatid mite had been spotted in all Carboniferous, Permian, and Triassic [5]. Contrary evidence, although rather conspicuous, was not
noticed or ignored: Clots with polygonal outline indicating angular shape (Figs.1-3) compatible with the sizes and shapes of nearby cells (Figs.2,3), occasionally arranged in files compatible with the cell files of the surrounding tissue (Fig.2), also as separate clots inside cells (Fig.3).
There are different types of tissue with differential cell sizes in the Ankyropteris axis. The clots in Fig.2 are compatible with the cell lumina of the tissue. Two chains of clots on the left look as if they had not been dropped there randomly. They look as if they had kept their positions where they had formed within the cells, a few remaining of which are seen below left. This suggests that the clots are casts of the cell lumina left over after the cell walls of the tissue which had been there where the clots are now had decayed. This idea is supported by several more observations based on own samples and pictures in other publications. clots of various sizes and shapes in Ankyropteris, no coprolites

Fig.4: Clots of various shapes and sizes in Ankyropteris, detail from [2], Fig.430, which is the same picture, upside down, as Plate VII1 in [1].

By looking carefully at the pictures in [1,2,3] one finds abundant evidence contradictung the claim that there are "two distinct size orders" of "coprolites". There are any sizes between tiny and rather big (Fig.4), like the cell sizes in the vicinity. Also the arrangement of these clots suggests that they had not been randomly dropped into a cavity by some creature.
The observation that the variation of sizes and shapes of the clots is the same as with the cells of nearby tissues provides another argument against the coprolite interpretation.

Finally it can be stated that lack of thoroughness has led to both the contradictory size data in [1,2,3] and the misconception of cell-size coprolites, which is still being upheld [6] despite of repeated warnings [7,8].
Wood rot due to fungus or microbial activity has to be taken into consideration as a cause of clot formation.
Samples: Museum für Naturkunde Chemnitz.
Annotation 2017: After several more publications trying to make believe that mite coprolites in fossil wood are real, the latest one from 2015 [9], and after the presentation of lots of contrary evidence on this website
, Rössler has apparently given up the idea.

H.-J. Weiss    2011,    2017

[1]  R. Rössler : The late palaeozoic tree fern Psaronius  -  an ecosystem unto itself.
      Rev. Palaeobot. Palyn. 108(2000), 55-74.
[2]  R. Rößler : Der versteinerte Wald von Chemnitz, 2001.
[3] R. Rössler : Between precious inheritance and immediate experience.
     in: U. Dernbach, W.D. Tidwell : Secrets of Petrified Plants. D'ORO Publ., 2002, 104-119.
[4]  J.T. Sterzel: Die organischen Reste des Kulms und des Rotliegenden der Gegend von Chemnitz.
     Abh. Königl. Sächs. Ges. Wiss., Math.-phys. Kl. 35(1918), 205-315.
[5] C.C. Labandeira, T.L. Phillips, R.A. Norton : Oribatid mites and the decomposition of plant tissues in paleozoic coal swamp forests.
     Palaios 12(1997), 319-53.
[6]  M. Barthel, M. Krings, R. Rößler: Die schwarzen Psaronien von Manebach, ihre Epiphyten, Parasiten und Pilze.
        Semana* 25(2010), 41-60.   *( recently re-named, former name: Veröff. Naturhist. Mus. Schleusingen)
[7] H.-J. Weiss: Rätselhaftes aus Hornstein und Kieselholz. 6. Chert Workshop 2007, Naturkunde-Museum Chemnitz.
[8] H.-J. Weiss: Märchenhaftes und Ernsthaftes im Hornstein. 8. Chert Workshop 2009, Naturkunde-Museum Chemnitz.
[9] 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.

quartz crystal with wood inside
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