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going into the outer cortical layers (Fig. 10a, d, f ).
These plants would have decayed to the state of
hollow tubes before being infilled with sediment.
Such casts are impossible to identify to generic
level, but the large size of some of these trunks
should be noted (up to 145 mm diameter); these
undoubtedly represent the trunks of moderately
tall lycopsid trees. One lycopsid showed detail
which is more likely to be the outer surface of the
plant, showing inverted U-shaped leaf attachments
lacking further details (Fig. 10e). These are superfi-
cially similar to some preservational states of
Cyclostigma from Bear Island (Bjørnøya) as illus-
trated by Nathorst (1902, plate 12, fig. 19a) although
diagnostic features are missing.
This contrasts with the Red Hill tetrapod locality
in Pennsylvania (Cressler 2006) where a diverse
Archaeopteris-dominated flora has been recorded.
It should be noted that the Red Hill flora is mainly
found in a fine-grained floodplain pond; such sub-
environments were not identified in the Celsius
Bjerg Group.
Conclusions
A detailed measured section is presented for the
Celsius Bjerg Group, East Greenland.
The sand bodies in the Britta Dal Formation are lat-
erally extensive, flat based and aggraded promi-
nently vertically. They are reinterpreted as the
deposits of a large fluvial system that was
subject to occasional very large flood events
when parts of the system became active. At
other times, soil processes dominated the silt-rich
floodplains to produce a succession dominated
by a spectacular sequence of vertisols.
The sand body that contains in situ Acanthostega
from the Britta Dal Formation on Stensi
¨
Bjerg was part of this ephemeral system and not
the deposits of a high sinuosity river channel
that
Obrutschew Bjerg Formation plant
macrofossils
Plants have been noted on the south side of Mount
Celsius since the 1950s (Blom et al. 2007, p. 129).
Plants found in 2006 are mainly flattened axes but
often retain carbon and/or impressions of the
cuticle/epidermis (Fig. 10g). This, the only speci-
men to show branching, is identical in its stem
surface details to the specimen illustrated by
Schweitzer (2006, plate 42, fig. 2) as Cephalopteris
tunheimensis from the Misery Series of Bear Island.
Although lacking any other diagnostic features, the
specimen should only be recognized as belonging
to this grade of organization.
the
tetrapods
could
have
inhabited
permanently.
The famous 1174 m Ichthyostega locality in Paral-
leldal is a flood-event sandstone of similar
origin that occurs just below the midpoint of
megacycle 2 in the Britta Dal Formation.
The fossil plants are generally restricted to the
poorly preserved remains of lycopods and
fern-like plants. Their preservation is entirely
consistent with both an origin as a transported
assemblage in common with the tetrapod fossils
and with the model for the Britta Dal Formation
sedimentary environment.
Plants and the tetrapod palaeoenvironment
Stratigraphically below the Obrutschew lake, the
preservation of plant fossils is very poor but shows
the existence of lycopsid trees and various fern-like
taxa. The fossils show high levels of de-cortication
and a lack of identifying features such as leaves.
Large logs, such as those to be expected from
archaeopteridalean trees, are so far absent. The
vegetation, which probably existed some distance
upstream from where it was transported, may there-
fore have been dominated by lycopsids and fern-like
plants rather than Archaeopteris. No evidence was
found of in situ plants (e.g. plant rooting structures)
despite the evidence of terrestrial surfaces and soils.
The continued support of CASP is gratefully acknowl-
edged, in particular the assistance of the other mem-
bers of the 2006 expedition (C. Johnson and
S. Johnson). M. Vecoli provided the impetus to complete
this contribution via the CNRS-sponsored Eclipse II
meeting on Terrestrialization Influences on the Palaeozoic
Geosphere - Biosphere. J. Clack kindly provided the speci-
men illustrated in Figure10c.
Fig. 10. (Continued ) Plant macrofossils from the Celsius Bjerg Group. Scale bar for (a-f ) is 50 mm, for (g-i) 10 mm.
(a) Lycopsid internal mould, 903 m altitude, Stensi¨ Bjerg Formation, southwestern Celsius Bjerg. (b) Indeterminate
axial plant fossils, Britta Dal Formation, 1174 m horizon, Profile Ravine, Paralleldal. (c) Fern-like quadriseriate frond.
Arrow shows vertically superposed lateral axes (collected by Clack and others in 1998 at 400 m altitude from east end of
Central Celsius Bjerg scree, presumably Brita Dal Formation). (d) and (e) Two lycopsids from a single block in scree
(probably Stensi¨ Bjerg Formation) from the bottom of the Aina Dal ravine, 555 m altitude. (f ) Lycopsid internal
mould, Stensi¨ Bjerg Formation, Nathorst Bjerg (432709, 8144714, GPS 927 m). (g) Fern-like branching axis, 1094 m
altitude, Obrutschew Bjerg Formation, southwestern Celsius Bjerg. (h) and (i) Indeterminate axial plant fossils,
(h) showing enlarged frond base and spine bases on surface and (i) showing sub-opposite branching. Britta Dal
Formation, 1174 m horizon, Profile Ravine, Paralleldal.
