The Ichnofacies Paradigm - Trace Fossils as Indicators of Sedimentary Environments - page 101

can be subdivided into landward and seaward expressions using the proportions
of terrestrial versus marine elements ( Curran, 2007 ).
The greatest expansion in ichnofacies archetypes has been seen in the con-
tinental realm (see Buatois and M´ngano, 2011 for a thorough summary). It was
always clear that the Scoyenia Ichnofacies could never hope to serve the range
of variability in animal/sediment relationships that occur in the continental
realm ( Bromley and Asgaard, 1979 ), but rather, it reflected the early focus
of ichnologists on marine and marginal-marine successions. Ichnofacies anal-
ysis of continental settings led first to three ichnofacies, with the revision of the
Scoyenia Ichnofacies ( Buatois and M ´ ngano, 1995 ), followed by the addition of
the Mermia Ichnofacies and the Coprinisphaera Ichnofacies ( Buatois and
M ´ ngano, 2004; Genise et al., 2000 ). More recently, the range of continental
ichnofacies has been expanded to six, with the inclusion of the Termitichnus
Ichnofacies (cf. Genise et al., 2000, 2010; Smith et al., 1993 ), Celliforma
Ichnofacies ( Genise et al., 2010 ), and Octopodichnus - Entradichnus Ichnofa-
cies ( Ekdale et al., 2007; Hunt and Lucas, 2007 ; see Buatois and M ´ ngano,
2011; Melchor et al., 2012 ; Tables 1 and 2 ). The latter three ichnofacies are
based on very few case studies and therefore are regarded as preliminary at
this time.
1.2 Variation in the Use of Ichnofacies
The use of ichnofacies has been uneven in the literature, in some ways paral-
leling the variations in the use of “facies”. Lockley et al. (1994) and Lockley
(2007) summarize the different scales of usage of the ichnofacies concept.
McIlroy (2004b) also provides a succinct table outlining some of the different
ichnofacies. The broadest usage of “ichnofacies” encompasses those erected
by Seilacher (1953a,b, 1964, 1967) as well as the few others that have global
and temporal recurrence, and have come to be known as “Seilacherian
ichnofacies” ( Bromley, 1990, 1996 ). These are discussed in greater detail in
Section 3 .
A number of distinctive, spatially recurring assemblages of trace fossils
have been given status as ichnofacies but do not adhere to the Seilacherian ich-
nofacies paradigm. Lockley et al. (1987) regard these to be “medium-scale ich-
nofacies” which operate as subsets of the Seilacherian ichnofacies. Some
workers consider these as “ichnosubfacies” (e.g., Seilacher, 1974; Uchman,
2001, 2009 ). Such subsets have been suggested to show widespread distribu-
tions in space and time, but insufficient case studies have been presented to date
to support this contention.
These include the Arenicolites Ichnofacies, the Curvolithus Ichnofacies, and
the Entobia Ichnofacies, among others. These non-Seilacherian ichnofacies do
not represent theoretical constructs that adhere to the rigors of the ichnofacies
concept. Additionally, they do not record distinctive ethological responses and
therefore do not aid in facies analysis. Such occurrences are not mappable and