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autecology of this form is poorly known although
the teeth reflect a function to process soft-bodied
prey. The presence of a single dorsal fin spine of
Ctenacanthus sp. suggests an aberrant occurrence
of this chondrichthyan that is known primarily
from marine deposits including the Cleveland
Shale, a distal equivalent of the Catskill Formation.
The palaeoniscid actinopterygian Limnomis
delaneyi (Fig. 6h) was small (4-6 cm total length)
and best preserved in the floodplain pond taphofa-
cies where large numbers of articulated individuals
have been collected. Some beds within the channel
margin and microfossil taphofacies also contain a
large amount of disarticulated material from L. dela-
neyi, or similar palaeoniscid(s). These primitive
actinopterygians had sharp teeth and presumably
ate small invertebrates and perhaps a variety of
organic debris, providing an important link
between the invertebrate and vertebrate components
of the ecosystem.
Dipnoan (lungfish) toothplates (Fig. 6g) are rare
at Red Hill and have been found primarily in the
potentially transported or reworked material of the
microfossil taphofacies. Significant dipnoan skull
material or scales have not been recognized. The
tooth plates were presumably for a durophagous
diet. Several articulated specimens of a distinctive
rhizodontid sarcopterygian (Fig. 6i), not yet
described, have only been recovered from the
plant-rich siltstone of the floodplain pond taphofa-
cies. These large (50 cm long) rhizodontids are the
only articulated sarcopterygians known in this
depositional setting. Its occurrence in pond sedi-
ments and the presence of large dentary, coronoid
and palatal fangs imply that this rhizodont was a
predator that specialized in ponded backwater set-
tings on the floodplain.
The remaining sarcopterygian fauna are also
medium- to large-sized predators. At least one
taxon of megalichthyid is present, although there is
cosmine-covered skull material and scales that rep-
resent a range of body sizes with estimated total
lengths 30-100 cm. The tristichopterid Hyneria
lindae was the largest of the sarcopterygians, reach-
ing a length of up to 3 m, and was the top predator in
the ecosystem. This taxon may have fed upon all
other fish and early tetrapod species. Although
taphonomic bias due to preservational and collecting
factors may influence the sample, the scales and
teeth of H. lindae are among the most commonly
encountered fossils at Red Hill.
The early tetrapods were also predatory animals,
eating fish and perhaps invertebrates. As with other
coeval tetrapods, particularly those known from
relatively complete remains such as Acanthostega
gunnari and Ichthyostega sp., these animals prob-
ably relied on aquatic ecosystems and had a
limited capacity for effective terrestrial locomotion.
Red Hill is the only Late Devonian site that has pro-
duced at least three penecontemporaneous early
tetrapod taxa (Daeschler et al. 2009). Densignathus
rowei was the most robust taxon with a wide lower
jaw including large coronoid fangs as found in more
primitive tetrapodomorphs and some early tetrapods
such as Ventastega curonica (Ahlberg et al. 1994,
2008; Daeschler 2000). The shoulder girdle of
Hynerpeton bassetti (Fig. 6j) indicates a smaller
taxon with a pectoral girdle similar to Acanthostega
gunnari (Daeschler et al. 1994, 2009). Several small
skull elements of a whatcheerid-like early tetrapod
have recently been recognized. These indicate a
more derived, steep-sided skull shape that may
reflect modifications to the mechanics of respiration
and prey capture (Daeschler et al. 2009). The diver-
sity of early tetrapods at Red Hill, though known
from only fragmentary material, indicates ecologi-
cal specialization even at this early stage in tetrapod
evolution. It seems likely such diversity is a reflec-
tion of the diverse ecological opportunities that
were present on the floodplains where a range of
habitats were formed by shifting geomorphic
regimes and lowland vegetation.
The Red Hill faunal assemblage is uniquely
diverse in the Catskill Formation and includes
several taxa that are not known from other sites in
the formation. Also of interest is the notable
absence of the antiarch placoderm Bothriolepis
and the porolepiform sarcopterygian Holoptychius
at Red Hill. Bothriolepis and Holoptychius
remains are very common in most other Catskill
Formation sites, and are common components of
Late Devonian freshwater and marginal deposits
around the world. The absence of these forms at
Red Hill may be a reflection of the palaeoenviron-
mental setting rather than a significant biostrati-
graphic difference. As far as can be judged from
palynomorph biostratigraphy, the Red Hill assem-
blage is the same age as many Bothriolepis and
Holoptychius-bearing sites in the Catskill Formation
and so we must conclude that the Red Hill ecosys-
tem was not suitable for these taxa. The fact that
Red Hill produces a unique fauna and that some
taxa that are common at most other Catskill For-
mation sites are absent at Red Hill suggests that
the palaeoenvironmental setting at Red Hill is rare
among Catskill Formation sites.
Discussion
Palaeobiogeographic distribution of the Red
Hill flora and fauna
Archaeopteris forests were distributed nearly glob-
ally and their fossil remains are known from
nearly every sedimentary basin with Late Devonian
terrestrial deposits. This includes many North
