Ichnotaxonomy: Finding Patterns in a Welter of Information - Trace Fossils as Indicators of Sedimentary Environments - page 52

TABLE 1 Generalized Morphological Characteristics of Some Ethological

Categories of Trace Fossils. Modified in Part after Frey and Seilacher (1980) —
Cont'd

Ethological category Characteristic morphology

Farming traces (agrichnia): traces made to
farm microbes or to trap meiobenthos.

Burrows originally open, parallel to
substrate surface, usually narrow; typically
complexly patterned (coiled, meandering,
networked), yet with unburrowed space
left between galleries.

Escape traces (fugichnia): traces made in
response to rapid burial.

Burrows showing upward adjustment of
the tracemaker, for example, vertically
repetitive resting traces, biogenic laminae
in vertical series.

Brooding traces (calichnia): traces made to
protect eggs and juveniles.

Burrows simple to complex, commonly
consisting of one or more chambers that
may be connected to adult-sized tunnels as
access but much smaller exit apertures or
tunnels for juveniles.

the identity of the tracemaker. And the overall form of the trace may outline the
body of the tracemaker itself. Trace fossils commonly classified as cubichnia
include Asteriacites, Rusophycus, and Limulicubichnus .

6.2 Dwelling Traces (Domichnia)
Dwelling traces, or domichnia, are open structures of which the primary func-
tion is to give the organism a permanent home: a place that affords protection
not only from competitors and predators, but also from temporary changes in
the local environment. Dwelling traces include burrows in soft and firm sub-
strates and borings in hard substrates. However, not all sediment dwellers live
in domichnia; many live permanently surrounded by the substrate. To excavate
and maintain an open burrow requires special adaptations on the part of the
tracemaker. An extensive literature may be consulted on burrowing methods,
morphological adaptations to burrowing, and burrow irrigation (maintenance
of water circulation) (e.g., Bromley, 1996; Sch ¨ fer, 1972; Trueman and Ansell,
1969; Vogel, 1978 ).
Domichnia are typically reinforced, lined, or at least smoothed off inter-
nally. Open borings in hard substrates and open burrows in firmgrounds typi-
cally need little reinforcement, but may be smoothly finished, and they may
be lined to limit influx of pore water from the substrate. Open burrows in soft