Maggot fern disputes
Why a Permian tree fern had got the
name "maggot fern", which is Scolecopteris
in Latin, can easily be guessed from the two pictures below,
taken from either half of a cut chert boulder collected at the type
locality of this fern in 1997. A
samples found before 1800 had aroused the imagination then, and given
to interpretations as creatures, until the fossil had been
recognized in 1802 as a plant and described as Scolecopteris elegans
in 1837 . This fossil had
considerably contributed to the
development of palaeobotany as a science, hence it is worth looking at
in detail. Later it became obvious that the foliage belongs to the
beautiful silicified Psaronius
Figs.1,2: Maggot fern (Scolecopteris)
pinnules in various states of preservation, more or less deformed,
suggesting interpretations as grubs or nymphs of
some insect. Images (widths 7mm and 8.5mm,
same scale) taken from
the cut halves of one chert layer fragment.
some of the capsules in Fig.1 had not been fully grown before frond
parts fell down into the water, accumulated
there, became deformed,
Note the red and yellow stains of spores in their mature capsules in
Problematic is another
chert sample from the same location with distinctly seen pinnules on
(Figs.3,4). Plant parts on chert layer
are clearly seen if they are preserved as hard chert after the
adjoining matter had been eroded away or spalled off.
Fig.3 (near left): Maggot fern
on the raw surface of a chert sample, pinnules
apparently not deformed.
Angle of veins about 60°. Same pinna as in ,
Fig.8, and , Fig.210A. Image width 11mm.
Fig.4 (far left): Pinnules from Fig.3, upper
row; epidermis texture following the veins towards the
margin. Image width 3.5mm.
The pinnules touch laterally in the depth, which is not seen here since
the gaps are filled
with whitish chalzedony. Apparently the fill had been left over when a
crack propagated along the cuticle on the
epidermis, jumped from one pinnule to the next, thus
whitish layer and laying bare the pinna as we see it now. The
waxy cuticle, if still present after silicification,
provides a potential crack path for
fern has been interpreted as Scolecopteris elegans in
[2,3] but recent finds of big synangium stalks
have given rise to doubts (Figs.5-7). For
comparison see the drawing
after the lectotype of Scolecopteris elegans
Table 1, showing a pinnule with very short synangium stalks (Fig.8).
In the same publication , pinnules
with big synangium stalks (Fig.9)
had also been assigned to Scolecopteris elegans,
which is highly questionable. A surprising answer concerning
big stalks is suggested
by Figs.5-7 instead.
Figs.5-7: Synangia with big stalks seen on cut faces of
the same chert sample as in Figs.3,4. Image sizes 1.5mm.
(Sample Bu8/18, coll. Wagner )
Note that the stalk may be not well seen
or not seen at all since the synangium axis most likely does not lie in
the arbitrarily chosen cut
plane. It seems to be slightly tilted to the cut plane in Fig.7 so that
stalk appears narrower than those in Fig.6, where their width is 0.27mm.
More synangia with big
stalks had been found earlier in a few more chert samples
this location, which indicates the presence of other species.
Fig.8 (below left): Pinnule cross-section drawn after the lectotype of Scolecopteris elegans as
defined in , width 2mm.
Fig.9 (below right): Pinnule
cross-sections with big synangium stalks drawn after ,
Table 5, coll. Etzold about 1890.
Despite of these obvious
differences and other features indicating the presence of other species,
Barthel had stated in
, p.75, that most probably there is only
one maggot fern species at the type locality of Sc. elegans.
, p.226, he sees more species there now.
However, referring to the sample Bu8/18 considered here, with
the same cut faces, he claims that the
fern is certainly Sc. elegans.
the synangia in Figs.5-7 are rather similar to those in Fig.9 but
differ much from the lectotype in Fig.8, most
likely they represent a
different species. If it were a known species
it should fit into one of the four groups proposed by Millay 
but it does not seem to fit well into any. The apically thick
sporangium wall would favour putting it together with Sc. elegans into
the "Minor group" but this is precluded by the big pedicel shaped as a
"broad cap of parenchyma uniting the sporangia to each other and to the
pinnule" [5,6]. This describes the pedicel of Sturiella
there but also fits surprisingly well to what is seen here in Figs.5-7.
did not notice these well visible synangia with big stalks, which had
been available to him on the cut sample faces. Also he did not notice
that a less well preserved synangium in his Fig.210B in  seems to be
of the same type as these ones. Hence, it is all Sc. elegans
to him, and he offers an extended description, allegedly of Sc. elegans,
based on three samples including Bu8/18 which probably
contains Sturiella only.
Such description, which probably is based on an error, is probably not
from Figs.5-7 indicates that Figs.6-8 in 
and Figs.210A-G in  are not "certainly Sc. elegans"
but possibly Sturiella intermedia.
This would be compatible with earlier own finds of synangia with big
pedicels and of sporangia with hairs.
In connection with
one need not avoid the familiar name "maggot fern" since Sturiella intermedia
1997) is also known as Scolecopteris
It may be mentioned here that
 and  are fraught with numerous inaccurate or erroneous
size data and other errors which may cause irritation. Example: Sc. elegans
spore sizes are 40µm on p.228, 70µm
in Fig.209, but 27µm in reality. See Google:
There are contradictory size data on Sturiella in [5,6].
Samples: Found by Uwe
Wagner (Dresden) in
1997 at the type location of Sc.
elegans and kept in his collection under the labels Bu8/23
(here Figs.1,2) and
Bu8/18 (here Figs.3-7).
ein neues fossiles Farrngewächs mit
Fructification. Linnaea 11(1837), 509-12.
The maggot stones from Windberg ridge.
in: U. Dernbach,
W.D. Tidwell: Secrets of
Petrified Plants, D'ORO Publ., 2002. p. 65-77.
Barthel: Die Rotliegend-Flora
der Döhlen-Formation. Geologica Saxonica 61(2), 2015, 108-229.
 M. Barthel,
W. Reichel, H.-J. Weiss: "Madensteine" in Sachsen.
Abhandl. Staatl. Mus. Mineral. Geol. Dresden 41(1995),
117-135, Table 1.
 M.A. Millay:
A review of
permineralized Euramerican Carboniferous tree ferns. Rev. Pal. Pal.
 A. Lesnikowska,
Galtier: A reconsideration of four genera of
permineralized Marattiales ... Rev.
Pal. Pal. 67(1991), 141-152.