Ichnotaxonomy: Finding Patterns in a Welter of Information - Trace Fossils as Indicators of Sedimentary Environments - page 44

(or section) determines the burrow's visible outline, which is ideally an ellipse,
and is only circular in the case of a burrow at right angles with the outcrop.
The beginner who wishes to pick up pointers on how to observe trace fossils
should read Howard (1978) as well as Bromley (1996) . Chamberlain's (1978)
well-illustrated primer on the recognition of burrows in cores is still valuable
although outdated by the ichnofabric atlas of Gerard and Bromley (2008) .
The best teacher is practice: the best ichnotaxonomist is the one who has seen
the most traces!
3. DESCRIBING TRACE FOSSILS
The terminology of trace-fossil description was standardized by Frey (1973) ,who
obtained an international consensus on terms. For further development of usage,
see H¨ntzschel (1975: W4) , Ekdale et al. (1984) , and especially Bromley (1996) .
This discussion will focus on the terminology of trace fossils that are most com-
monly given Linnaean names: tracks, trails, burrows, and borings. A general term
for any sign of organismal activity without regard to time is trace .
Traces are physical objects consisting of previously existing material (a sub-
strate ) that has been altered by biological activity. They extend in three dimen-
sions, have an orientation, are made up of sediment or other material, and have
boundaries with regard to the surrounding substrate. In short, they can be
described in a rigorous and repeatable manner. All classifications of traces
ultimately depend on morphological description.
In general, a track is a single imprint made by the appendages of an animal
on the surface of the substrate, while a trackway is a series of tracks. A trail is a
continuous trace made on the surface of a substrate, while a burrow is a contin-
uous trace made within a substrate. The orientation of a trace refers to the angle
of its longest dimension with regard to the surface of the substrate; this is usually
simplified as horizontal, subhorizontal, oblique, subvertical, and vertical .Itis
worth knowing that, even if an observer has no other information on the trace
fossils of a bed, their general orientation can yield information on surface con-
ditions such as wave energy, because animals dig vertical burrows to escape
from difficult surface conditions ( Seilacher, 1953 ). Most nameable burrows
have a more or less defined contact with the surrounding sediment; this is
the burrow's wall or boundary . Material added to this boundary may be called
a lining, as discussed further by Bromley (1996) and Zorn et al. (2010) .
4. STRATINOMIC CLASSIFICATIONS
4.1 Substrate Consistency
Stratinomy is the study of sedimentary processes that lead to the preservation of
a sedimentary record, with biostratinomy referring to sedimentary processes
that affect the remains, including traces, of organisms. Processes that lead to