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ecology of this early forest ecosystem (Cressler
2001, 2006). Previous work based on light
microscope and SEM analysis of preserved xylem
in the charcoal samples only showed evidence of
Rhacophyton being burned in this landscape
(Cressler 2001). An earlier ecological interpretation
suggesting that the shallowly rooted Rhacophyton
became desiccated during the dry season and
became vulnerable to burning, whereas the deeply
rooted Archaeopteris was relatively unaffected by
fire, is perhaps unfounded. The abundance of
small fragments of Rhacophyton-derived charcoal
in the floodplain pond sediments reflects tapho-
nomic sorting bias in the earlier sampling (Cressler
2001, 2006). Since these previous publications, a
2 cm piece of charcoal has been found in a sand-
stone lens at Red Hill that most likely came from
Archaeopteris (Callixylon) wood. Furthermore,
reflectance analysis on Red Hill charcoal (mean
R
o
¼ 4.4%; mode ¼ 4.75%) indicates that the fires
were predominantly 575 8C and within the tempera-
ture range of modern forest crown fires (Hawkins
2006). A similar phenomenon may have existed
among Archaeopteris forests.
Nevertheless, the pattern of centimetre-scale
succession in the sampled plant horizon at Red
Hill shows the appearance of spermatophytes fol-
lowing the burning of Rhacophyton in presumed
ground fires on a local scale. Perhaps spermato-
phytes were able to establish themselves quickly
in burned patches due to their unified sporophyte
and gametophyte generations. Obstructions imposed
on their airborne pollination mechanism by sur-
rounding dense vegetation also would have been
reduced. In any case, fire became an important
factor in the dynamics of Late Devonian plant com-
munities, contributing to the frequently changing
spatio-temporal distribution of plants in the patch-
work mosaic of this landscape.
waters in the Catskill Delta system, and the micro-
organisms that were supported, can be found at
other localities where dense concentrations of
filter feeding bivalves (cf. Archanodon sp.) are
preserved in living position (Remington et al. 2008).
The increase in stature and rooting depth of
riparian vegetation not only stabilized floodplains
and affected the dynamics of channel and floodplain
pond formation, but the influx of large plant debris
into the aquatic ecosystem also had structural impli-
cations for underwater habitats. Smaller organisms
had more complex areas in which to hide, and larger
organisms had more complex substrates over and
through which to move. While the influx of organic
matter enriched these environments and supported
diverse aquatic ecosystems, it also created enhanced
conditions for anoxia (Algeo & Scheckler 1998).
Trophic structure of the Red Hill ecosystem
The following is a hypothetical model of trophic
relationships based on evidence from sedimentol-
ogy, taphonomy and the interpretation of functional
morphology. This model is necessarily simple in
order to avoid over-interpretation.
By the Late Devonian there was an increase in
primary productivity on land that became a source
of a large volume of organic debris that was metab-
olized by micro-organisms in freshwater ecosys-
tems. Aquatic invertebrates were probably taking
advantage of this resource, but the evidence at Red
Hill is limited to the activity of trace makers.
There is no evidence of herbivory on living plant
tissues but detritivores are in evidence, including
the myriapods Orsadesmus rubecollis (Fig. 6e)
and a putative myriopod trackway (Fig. 6d). Preda-
tory terrestrial invertebrates included the trigonotar-
bid Gigantocharinus szatmaryi (Fig. 6f ), as well as
reported remains of scorpions which have not yet
been described.
Among vertebrates, the groenlandspidids Groen-
landaspis pennsylvanicus and Turrisaspis elektor
were small- to moderately-sized placoderms with
ventrally oriented mouths suggesting that these
animals were detritus feeders at the water-sediment
interface. Their head-and-body shape also suggests
a hydrodynamic design for staying close to the sub-
strate. The same feeding mode also may apply to the
phyllolepid placoderm, Phyllolepis rosimontina,
which is less common at the site. The large gyra-
canthid acanthodian, Gyracanthus (cf. G. sher-
woodi), was probably an open-water filter feeder,
subsisting on primary producers and small primary
consumers within the water column. The small
chondrichthyan, Ageleodus pectinatus, is known
only from isolated teeth found primarily in the
microfossil taphofacies. The teeth show no sign of
wear facets (Downs & Daeschler 2001) and the
Role of organic debris
The increase in size and distribution of land plants in
the Late Devonian increased the amount of organic
matter available for burning, nutrient availability
and burial in depositional systems (Algeo et al.
2001). Evidence for high organic detrital influx into
the fluvial regime is readily apparent at Red Hill.
Floodplain pond deposits contain a high density of
organic matter consisting of well-preserved foliage
and stems of plants, fragmented debris and charcoal.
Many of the bedding surfaces within the reduced
siltstone facies are dark in colour (Munsell N 4/*)
due to organic content.
Along with organic debris, mineral nutrients
entered the aquatic ecosystem at an increased rate
due to increased soil weathering by plants (Algeo
& Scheckler 1998). Evidence for nutrient-laden
