Calamite offspring
deutsche Version

The Palaeozoic horsetail trees known as calamites [1] are commonly found as stem casts [2], pith casts, or as compressions of their hollow stems, branches and leaves in sediment rocks between coal seams [3]. Less common are thoroughly silicified specimens, notably those of species with solid wooden stems superficially resembling coniferous tree trunks of potentially big size ([4], see Fossil Wood News 15).
In the following, attention is drawn to the less conspicuous tiny calamite offspring which apparently covered suitable spots of soil or mud in great numbers. In the cherts of the Lower Permian Döhlen basin, calamites are found among the remains of tree ferns as a rarer component of the silicified swamp matter, or as uniform stands of juvenile plants lying flattened and aligned as if upset by a flash flood (Fig.1).
small calamites in Permian chert18 calamite cross-sections on 20 square cmFig.1: Chert face with 18 or more cross-sections of small calamites of various size on 20cm2, lying aligned and flattened.
Width of the picture (= frame in drawing) 5cm.

Fig.2 (below): Tiny calamite in chert, silicified while in upright position. Note the cross-sections of upright setaceous leaves keeping close to the stem (on the right).
Stem diameter 5mm.
tiny calamite in Permian chert

Well preserved small calamites seem to be very rare in the cherts. The one in Fig.2 is a unique find. It became silicified while being inundated in swamp water, judging from tree fern pinnules and moult fragments of the aquatic crustacean Uronectes in the same sample.

It has to be mentioned that Fig.2 had been interpreted as a calamite branch cross-section [5]. The alternative interpretation as a small stem as proposed here is based on the following observations:
The object is standing upright in the chert layer. Its length does not much exceed 3cm. The leaves are setaceous and stiff upright, gradually converging towards the top.
This gives rise to the following thoughts: Calamite branch fragments would most probably be lying prostrate in the chert layer, be longer, and have broad outspread leaves, which justifies the tentative assumption that the present specimen is no such.

Fig.3 (below): Tiny calamite, detail of Fig.2. Note the beginning growth of wood with small cells outward from every red spot, the onset of the primary "pith rays" in between, the distinctly seen cortex tissue, and the slightly displaced epidermis. Width of the picture 2.5mm.     Annotation 2016: A detail of Fig.3 is shown in [6], Fig.75a, too small by a factor 2.8.
tiny calamite in Permian chert
The central pith and the protoxylem strands have vanished. The cavities left by the latter have become stained red with hematite. The red spots mark the apex of the wood wedges which would have grown if the plantlet had lived on. Parenchymatic tissue between the spots would have grown into "pith rays". Remarkable is the preservation of the cortex tissue with its large cells. The outermost sheath with the epidermis appears detached and slightly displaced.

Photographs: Figs.2,3 by M. Barthel. The samples are kept in the own collection.
Fig.1: Bu4/59.3, found in 1995 on the property of  F.+ U. Lippert,  Freital-Burgk, Bernhardts Weg 25.
Fig.2: Bu7/46.1, found in 2000, Freital-Kleinnaundorf, Kohlenstr.,
   type locality of the Scolecopteris tree fern. Döhlen basin near Dresden, Saxony. 

H.-J. Weiss     2012

[1]  T.N. Taylor et al.: Paleobotany. Elsevier 2009
[2]  W.A. DiMichele, H.J. Falcon-Lang: Calamitalean "pith casts" reconsidered. Rev. Palaeobot. Palyn. 173(2012), 1-14.
[3]  W. Reichel, M. Schauer: Das Döhlener Becken bei Dresden. Bergbau in Sachsen, Band 12. Freiberg 2006.
[4] R. Rößler, R. Noll: The largest known anatomically preserved calamite, an exceptional find from the petrified forest of Chemnitz.
      Rev. Palaeobot. Palyn. 140(2006), 145-62.
[5]  M. Barthel: Paläobotanische Aspekte des Döhlen-Beckens. Veröff. Museum für Naturkunde Chemnitz 27(2004), 17-28.
[6]  M. Barthel: Die Rotliegendflora der Döhlen-Formation. Geologica Saxonica  61 (2) 2015, 105-238.
Scolecopteris pinnule cross-section, Sardinia Permian Chert News10

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