Environmental Engineering Reference
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( Buatois and M´ngano, 1996, 2004, 2007, 2011; Pollard, 1988 ). The purpose of
this chapter is to evaluate the link between trace-fossil assemblages and ichno-
facies with different fluvial subenvironments, with emphasis on the utility of
trace fossils in the paleoenvironmental analysis.
2. APPROACH
We have attempted to revise the present knowledge on the sedimentary facies
distribution and ichnofacies assignment of published assemblages of trace fos-
sils including invertebrate, vertebrate, and plant trace fossils. The number of
ichnogenera recorded in fluvial deposits is over 170 (and more than 20 trace-
fossil types are left in open nomenclature); their identification requires special
skills and training that are, to some extent, more properly conducted by special-
ists. In the description of any trace-fossil assemblages, a careful ichnotaxono-
mical assignment of every trace-fossil type is highly desirable. However, for the
practical purposes of this chapter, essentially aimed toward sedimentologists, a
more simple classification scheme is adopted, largely based on morphological
attributes that can be easily distinguished in the field. This classification scheme
( Table 1 ) is not comprehensive, rather it is intended to cover only the ichnotaxa
recorded in fluvial facies, although it can be extended to include other trace-
fossil types and environments (see also the proposal by Knaust, 2012 ). Each
category is equivalent to one or more ichnogenera, and no distinction at the ich-
nospecies level is considered. Some trace-fossil categories adopted herein have
been used in an informal way in the ichnological literature, and most of them are
proposed herein ( Table 1 ).
The fundamental biogenic structures that are recognized include burrows,
trails, tracks, trackways, chambers, nests, rhizoliths and other root structures,
and coprolites ( Frey and Pemberton, 1985; Klappa, 1980 ). Bite and gnaw struc-
tures on bone and borings in wood do occur in fluvial successions, but they have
been used mostly for taphonomical and paleoecological analyses (e.g., Roberts
et al., 2007; Uchman et al., 2007 ), though their applicability in facies analysis is
not yet clear. In consequence, these structures are not considered further in
this chapter. For tetrapod trackways, the classification is based on a hierarchy
of features starting by the quadrupedal or bipedal locomotion of the producer of
the trackway (Q, quadrupedal; B, bipedal), then the overall track outline
(rounded, triangular), the number of digits on manus and pes tracks (manus-
pes for quadrupedal, alternative number of digits impressions for bipedal tracks
are separated by a dash), digit morphology (sl, slender; tk, thick; st, stout; d, dot-
like), and pace angulation (pa). As shorthand for a category of tetrapod tracks, a
formula or abbreviation is used that is composed of the following terms: nature
of trackway in capital letters
þ
þ
morphology of footprints in lower case
num-
þ
þ
ber of digits manus/number of digits pes
pace angulation
(e.g., “Q rounded 5/5”). The basic components of this formula are the nature of
the trackway and the number of digits in manus and pes ( Table 1 ). Although
digit morphology
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