Geoscience Reference
In-Depth Information
taphofacies at Red Hill. These deposits represent
low-energy, reducing environments such as flood-
plain ponds and distal splay settings that can
provide excellent temporal and ecological fidelity.
Otzinachsonia beerboweri (Cressler & Pfefferkorn
2005), are also present. Spermatophytes are
present as both Moresnetia-like cupules (Fig. 6b)
and Aglosperma sp (Cressler 2006). The palynologi-
cal age of the strata make it coeval with the ages of
other sites with earliest recorded spermatophytes in
Belgium and West Virginia (Fairon-Demaret &
Scheckler 1987; Rothwell et al. 1989). Other
minor floral elements include the stauripterid fern
Gillespiea and a variety of barinophytes (Cressler
2006). Major plant groups found at other Late Devo-
nian sites but not yet discovered at Red Hill are the
sphenopsids and cladoxylaleans.
Distribution of habitats at Red Hill
The floodplain habitats at Red Hill provided a range
of conditions for the cohabitation of plants and
animals. Plant communities were partitioned on
the floodplain across a range of environments from
elevated and better-drained levees to low, wetland
habitats (Cressler 2006). The aquatic settings
include open river channels, shallow channel
margins, anastomosing temporary channels and
floodplain ponds in interfluves that were subject to
periodic flooding. This heterogeneity is expressed
even on the local scale at the Red Hill site, as
might be expected with the avulsion model of flood-
plain aggradation. Seasonal flooding and drying
probably had a significant role in the annual cycles
of plants and animals.
Faunal diversity
Table 2 presents a list of Red Hill fauna recognized
to date. The arthropod fauna is likely only a very
limited subset of the invertebrate community that
was in the floodplain ecosystem. A trigonotarbid
arachnid (Fig. 6f ) and an archidesmid myriapod
(Fig. 6e) have each been described from the stand-
ing water taphofacies, but greater diversity is evi-
denced by enigmatic body impressions, burrow
traces and walking traces (Fig. 6d).
The vertebrate assemblage represents a diverse
community that was living in aquatic habitats
within the alluvial plain of the Catskill Delta
Complex. These include bottom feeders, duro-
phages, filter feeders and a wide range of predators.
The placoderm assemblage is dominated by the
small groenlandaspidid, Turrisaspis elektor, one of
the most common taxa from the site (Daeschler
et al. 2003). Fin spines and pectoral girdle elements
of the acanthodian Gyracanthus (cf. G. sherwoodi)
are also quite common. Among the bony fish
fauna (osteichthyans), the small palaeoniscid acti-
nopterygian Limnomis delaneyi (Fig. 6h) and the
large tristichopterid sarcopterygian Hyneria lindae
are the dominant components. Early tetrapod
remains are very rare and are represented by isolated
skeletal elements, although recent analysis suggests
that at least three penecontemporaneous taxa are
present (Daeschler et al. 2009).
Age of the deposit
Palynological analysis has placed Red Hill within
the poorly calibrated VH palynozone (Traverse
2003), but it is less ambiguously attributed to the
VCo palynozone (sensu Streel et al. 1987) within
the Famennian Stage, Late Devonian Period. This
zone is defined by the first occurrence of the palyno-
morph index species Grandispora cornuta Higgs
and Rugispora flexuosa (Juschko) Streel, among
others (Richardson & McGregor 1986; Streel &
Scheckler 1990). A revision of Late Famennian
zonation in Belgium will possibly place Red Hill
firmly within the VH Spore Zone (Maziane et al.
1999) and therefore within the trachytera to
middle expansa Conodont Zones of the upper
Famennian Substage (Streel & Loboziak 1996).
Red Hill flora and fauna
Floral diversity
The floral characteristics of the site are typical of a
Late Devonian plant assemblage, a subtropical
Archaeopteris forest (Table 1). Four Archaeopteris
leaf morphospecies are dominated by A. macilenta
and A. hibernica (Fig. 6a). This progymnosperm
tree is an index fossil for the Late Devonian
(Banks 1980), as is the second most abundant set
of plant remains at Red Hill, the zygopterid fern
assigned to Rhacophyton (Fig. 6c). The early diver-
sification of arborescent lycopsids are represented
by numerous decorticated stems, some identifiable
as Lepidodendropsis. Well-preserved remains of
cormose isoetalean bases and stems, described as
Palaeoecological setting at Red Hill
Vegetation
A previous palaeoecological analysis of the Red Hill
plant community characterized the vegetation as a
subtropical Archaeopteris floodplain forest inter-
spersed with lycopsid wetlands and widespread
stands of Rhacophyton on the floodplain and along
water margins (Cressler 2006). Taphonomic and
fossil-distribution evidence was derived from the
systematic sampling of the floodplain pond deposit
containing plant fossils that had undergone little or
