Fluvial Environments - Trace Fossils as Indicators of Sedimentary Environments - page 325

M´ngano, 1995; Genise et al., 2000; Smith et al., 1993 ). The invertebrate ichno-
facies recognized in fluvial deposits include the Scoyenia , Mermia , Coprini-
sphaera ,and Skolithos ichnofacies (e.g., Buatois and M´ngano, 2007 ). To this
scheme can be added the recently proposed Celliforma Ichnofacies and the poten-
tially distinctive and redefined Termitichnus Ichnofacies ( Genise et al., 2010 ).
In contrast, the proposal of vertebrate ichnofacies or the incorporation of ver-
tebrate trace fossils to a unified ichnofacies scheme has been controversial
( MacEachern et al., 2012 ). The development of the concept of vertebrate ichno-
facies is in an early stage, and there is still much debate and disagreement on the
nature of each ichnofacies, the criteria used in its definition, and even the useful-
ness of the concept in vertebrate ichnology (e.g., Santi and Nicosia, 2008 ). The
principles utilized for recognition of potential vertebrate ichnofacies are not the
same as those applied to the establishment of invertebrate ichnofacies. These dif-
ferences have been recognized, and a suggestion was made to distinguish two
kinds of ichnofacies ( Hunt and Lucas, 2005 ): one that reflects behavioral inter-
actions between the organisms and the substrate (ethoichnofacies) and another
that attempts to relate tracks and traces to the taxonomy of the producer (biotaxo-
ichnofacies). Lockley and coworkers ( Lockley, 2007; Lockley et al., 1994 )rec-
ognized a number of vertebrate ichnocoenoses as candidates for vertebrate
ichnofacies; although most of the ichnofacies were established on the basis of
few case studies, their recurrence in time is limited and, in many cases, the ich-
nofacies also display a restricted geographical distribution ( Melchor et al., 2006 ).
Hunt and Lucas (2007) revised the proposal of Lockley et al. (1994) and presented
a number of newly defined vertebrate ichnofacies that are composed of individual
ichnocoenoses (many of them comparable with the “ichnofacies” of Lockley
et al., 1994 ). The vertebrate ichnofacies of Hunt and Lucas (2007) were conceived
as parallel to invertebrate archetypal ichnofacies. Although a unification of the
ichnofacies scheme is considered desirable, we follow herein the proposal of ver-
tebrate ichnofacies by Hunt and Lucas (2007) . This proposal, even if it is too
broad and displays internal inconsistencies, is considered a useful template for
further discussion and refinement. This scheme is preferred over the Lockley
et al. (1994) proposal because, in the latter, the proposed ichnofacies have a high
ichnostratigraphical component (time dependence), except in the case of the
“shorebird ichnofacies”.
The vertebrate ichnofacies of Hunt and Lucas (2007) that are found in fluvial
deposits include the Grallator and Batrachichnus ichnofacies ( Hunt and Lucas,
2007; Lockley, 2007; Lockley et al., 1994 ). Other proposed ichnofacies that
may occur in fluvial deposits lack the recurrence in time and space, to be con-
sidered as considered as archetypal, and are probably best viewed as particular
ichnocoenoses: these are the Characichnos or Hatcherichnus ( Hunt and Lucas,
2007; Lockley et al., 2010 ), Chelonipus ( Lockley and Foster, 2006 ), and Bron-
topodus ( Hunt and Lucas, 2007 ) “ichnofacies”. Although the studies on verte-
brate coprolites and the application of ichnotaxonomic names to coprolites are
in their infancy, a coprofacies has also been recognized ( Hunt et al., 1994 ).