The Ichnofacies Paradigm - Trace Fossils as Indicators of Sedimentary Environments - page 109

echiurans, mollusks, nematodes, and tetrapods. Erecting a parallel ichnofacies
framework for the tracks and trackways of some (but not all) of the represen-
tatives of a single one of the

35 phyla in Kingdom Animalia is neither nec-
essary nor particularly helpful from a depositional- or environmental-
interpretation standpoint. Consequently, we do not consider any of the tetrapod
“ichnofacies” to be valid. Rather, these ichnocoenoses are taxonomically
restricted components of globally occurring, taxonomically inclusive continen-
tal or marginal-marine ichnofacies such as the Psilonichnus Ichnofacies, Scoy-
enia Ichnofacies, and Octopodichnus - Entradichnus Ichnofacies.
The sedimentary facies concept traveled a similar path in themid-1900s, with
some advocating the limiting of facies to “areally restricted parts of a designated
stratigraphic unit” (e.g., Moore, 1949 ). This departedmarkedly from the original
intended use of the concept ( Gressley, 1838 ) and ultimately was abandoned.
Middleton (1973, 1978) and Reading (1996) provide excellent and instructive
summaries of the rationales for the stratigraphically unrestricted usage of facies.
Ultimately, the identification of temporally and spatially restricted “ichnofacies”
undermines the paradigm's broad application to environmental interpretation.
As Bromley (1996) points out, temporally and spatially restricted but neverthe-
less recurring groupings of trace fossils have a use, but should be designated by a
different term. We would argue that the Seilacherian approach yields the only
true ichnofacies, and that the term should be employed in the manner that it
was originally intended. This preserves the usefulness of the paradigm for facies
analysis and depositional environment reconstruction.

2. NEOICHNOLOGICAL UNDERPINNING OF
SEILACHERIAN ICHNOFACIES
Neoichnological research—and a range of biological studies that are unwittingly
neoichnological in character—ratifies contemporary interpretations of ichnofa-
cies (e.g., Dashtgard, 2011a; Genise et al., 2000, 2010; Gingras et al., 2004;
Hertweck, 1972; Lawfield and Pickerill, 2006; Scott et al., 2009; Virtasalo
et al., 2011; Wetzel, 2008 ). That is to say, neoichnological observations support
the assertion that ichnofacies reflect broad animal behavioral responses to envi-
ronmental conditions, wherein animal ethologies collectively are associatedwith
strategies of survival and procreation. Specifically, neoichnological observa-
tions confirm the relationship between food-resource distribution, sediment cal-
iber and consistency, and feeding behavior, which forms the premise for the
ichnofacies paradigm (e.g., Curran and Martin, 2001; Dafoe et al., 2011; Dasht-
gard et al., 2008; Genise et al., 2000, 2010; Gingras et al., 2007a,b, 2008a,b, 2011;
Howard et al., 1974; Reineck, 1968 ). Departures from established archetypes are
apparent where factors such as salinity and oxygenation play an increasingly
important role (e.g., Bann et al., 2004, 2008 ; Dashtgard, 2011b; Gingras et al.,
2001; Howard and Frey, 1975; MacEachern and Gingras, 2007; MacEachern
et al., 2005, 2007b ; Rhoads and Morse, 1971 ). Buatois and M´ngano (2011)