The Ichnofacies Paradigm - Trace Fossils as Indicators of Sedimentary Environments - page 125

the entire Phanerozoic. Additionally, the ichnogenus Coprinisphaera has not
been identified in rocks older than the Paleocene, although equivalent suites
lacking the namesake could extend the utility of the ichnofacies further back
in time. In an even more confusing manner, the Glossifungites Ichnofacies con-
tinues to exist, while the namesake ichnogenus “ Glossifungites ” has been
deemed invalid, and is considered a scratch-marked expression of Rhizocoral-
lium (e.g., F¨rsich, 1974; Uchman et al., 2000 ).
Future work should see the increased integration of process-based neoich-
nological data with observations from the rock record. Additionally, develop-
ment of numerical analysis and statistical evaluation schemes is desirable as a
means of expressing ichnological relationships. Refinements in the application
of the ichnofacies concept to continental strata have seen great strides over the
past decade (see Buatois and M ´ ngano, 2011; Melchor et al., 2012 ). Neverthe-
less, the application of ichnofacies to these complex settings has proved diffi-
cult, owing to taphonomic considerations and the extreme lateral variability in
many of the environmental parameters. For those that enjoy a challenge, this is
an exciting area of research that is likely to continue to expand. Finally, most
Seilacherian ichnofacies have been defined to accommodate ambient (largely
unstressed) settings. The development of additional ichnofacies is likely but
will need to be approached carefully. Defining new Seilacherian ichnofacies
requires multiple case studies (both modern and ancient) and clear-cut ethologi-
cal groupings by which the appropriate trace-fossil suites can be recognized.
Analysis of case studies from all over the world and from all life-bearing periods
of geological time is essential in order to ensure the validity of any newly
defined Seilacherian ichnofacies.
Critics of the ichnofacies approach question its utility by implying that
trace-fossil suites and ichnofabrics are “lumped” into broad entities that are then
assigned to a limited number of environments (e.g., Goldring, 1993; McIlroy,
2004b; Taylor and Goldring, 1993; Taylor et al., 2003 ). Their concern is that the
details imparted by the observed ichnological suites and ichnofabrics become
downplayed in the interpretation of the facies. A similar criticism has been
leveled against sedimentological facies models ( Dalrymple, 2010 ). However,
to turn the phrase of Walker (1992) , it is the generality embodied by the ichno-
facies, as opposed to the summary of one particular case study, which enables
the ichnofacies paradigm to serve its most valuable functions.
One does not evaluate a sandstone interval and assign a shoreface interpre-
tation simply because it hosts suites attributable to the Skolithos Ichnofacies, for
example. The Skolithos Ichnofacies is not diagnostic of middle and upper shore-
face environments. Rather, the middle shoreface and upper shoreface environ-
ments commonly host suites of the Skolithos Ichnofacies, precisely because
they possess the depositional conditions that favor those ethological and trophic
groupings. Other environments host suites attributable to the Skolithos Ichno-
facies as well, because they also possess the physico-chemical parameters upon
which the ichnofacies is founded. The details of the trace-fossil suites,