No mite coprolites inside Vertebraria and Australoxylon wood
deutsche Version

The idea of orbatid mite coprolites in the Palaeozoic seems to be so resilient to contrary evidence that it must be rejected every time anew. (See "Wood rot or coprolites". ) Although repeatedly presented arguments have caused some palaeontologists to retreat half-heartedly by ascribing the cell-size clots to "unknown creatures" [1] or "new detritivores" [2] instead of oribatid mites [3], every now and then one stumbles upon publications based on the old notions. One of such concerns two types of Permian wood named Vertebraria and Australoxylon, referring to roots and stem of a glossopterid tree, with "Galleries ... filled with ... spherical coprolites ... from oribatid mites" [4]. Only a few details from images in [4] are sufficient to show that there are no "spherical coprolites" and hence no "oribatid mites".
no coproliteswood tissue
no coprolites10
Figs.1,2,3: Alleged coprolites: Details from [4], Plate 5.1 and 5.3 (far right). Width of the pictures 0.5mm.

The clots seen here are not at all "spherical" but angular. They are not of "uniform size" but vary in shape and size like the (partially collapsed) cells of the nearby tissue only 1mm away (Fig.2). Hence, most probably they were formed inside cells as a kind of wood rot and came out when the cell walls broke down.


Fig.4: Cell-size clots, alleged coprolites in [5], shown here for comparison.

Judging from experience, the clots in Fig.3, although not as obviously related to cells as those in Fig.4, do not look like coprolites. There are two lengthy clots above and below in Fig.3 which seem to consist of three cells in a row with dark fills.

The few details presented here reveal that essential claims in [4] lack any fossil evidence:
"The coprolites in Vertebraria and Australoxylon occur in clusters of variable numbers."
"The morphology of these coprolites suggests production by oribatid mites."
"Galleries in Vertebraria ... filled with small clusters of spherical coprolites are here interpreted to derive from oribatid mites."
"Characteristics that particularly favour oribatid mites as the originators of the small coprolites include their clustered distribution, uniform size ..."

Obviously the publication [4] is fraught with a lot of redundance and unsubstantiated statements inspired by wishful thinking. This applies to [6], too. Also there are inconsistent size data. By comparing the images 5 and 6 on Plate 5 it appears that at least one of the scale bars is erroneous. Furthermore, the clots are not "120 m long and 115 μm wide" as claimed in Table 1 but 25...100m long and 25...75m wide.
[4] refers to quite a number of other publications with highly questionable inferences on alleged oribatid mite coprolites which have been rejected before: See  Fossil Wood News 16
and "Wood rot or coprolites". Apparently no oribatid mite has ever been seen along with the "coprolites". It would be interesting to know whether or not there are real oribatid mite coprolites among the alleged ones. If not, the once favourite subject should better fall into oblivion soon, or be remembered as a folly of palaeobotanists who did not inspect their fossils carefully.

H.-J. Weiss   2014

[1]  M. Barthel, M. Krings, R. Rler: Die schwarzen Psaronien von Manebach, ihre Epiphyten,
      Parasiten und Pilze. Semana 25(2010), 41-60.    
( recently re-named, former name: Verff. Naturhist. Mus. Schleusingen)
[2]  Zhuo Feng, Jun Wang, Lu-Yun Liu, R. Rler: A novel coniferous tree trunk with septate pith from the Guadelupian (Permian) of China.
      Int. J. Plant Sci. 173(2012), 835–848.
[3]  R. Rler: The late palaeozoic tree fern Psaronius  -  an ecosystem unto itself.
      Rev. Palaeobot. Palyn. 108(2000), 55-74.
[4]  B. Slater,  S. McLoughlin, J. Hilton:  Animal–plant interactions in a Middle Permian permineralised peat ..., Prince Charles Mountains, Antarctica.
      Palaeogeogr. Pal. Pal. 363-364 (2012), 109-126.
[5]  D.W. Kellog, E.L. Taylor : Evidence of oribatid mite detrivory in Antarctica during the Late Paleozoic and Mesozoic,
      J. of Paleontology 78(2004), 1146-53.
[6]  B. J. Slater: Fossil Focus: Arthropod–plant interactions.
      Palaeontology [online] (2014), Vol.4, Article 5.
quartz crystal with wood inside
Fossil Wood News 22

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