A History of Ideas in Ichnology - Trace Fossils as Indicators of Sedimentary Environments - page 22

FIGURE 4 Important personalities of the Modern Era. (A) Adolf Seilacher. (B) James Howard.
(C) Marian Ksi˛˙kiewicz.
by earlier taxonomical categorizations such as those by Richter and Krejci-Graf
(see also H¨ntzschel, 1975 : W17).
During the same years, ichnologists started to pay attention to the spatial
arrangement of trace fossils. Seilacher (1953, 1964) and Martinsson (1965)
developed two different toponomical classifications, both based on the spatial
relationship between a trace fossil and its casting medium (see Bromley, 1996
and Rindsberg, 2012 , for a detailed treatment of both classifications). The set of
terms introduced by Seilacher and Martinsson were rapidly adapted as a pow-
erful and easy-to-use descriptive tool.
In his forward-looking article, H¨ntzschel (1955) recognized the value of the
Spuren-Vergesellschaftung (trace-fossil association) for the characterization of
sedimentary environments and Ichno-Fazies . These principles were emphasized
by Seilacher's ethological approach, stating that trace fossils reveal fossil behav-
ior and, as such, can be modified by the environment. Seilacher discerned
the divergence between shallow-marine and deep-sea trace-fossil assemblages
at a global scale and throughout the Phanerozoic ( Pemberton et al., 2001;
Seilacher, 2007 ). These propositions were the cornerstone for the ichnofacies
concept, originally consisting of six sets of traces named for a characteristic
ichnotaxon and related to a bathymetric gradient ( Seilacher, 1967 ). Ichnofacies
are distinctive, recurring ethological groupings of traces with specific environ-
mental significance. Initially, paleobathymetry was the principal controlling fac-
tor, but more environmental implications underlie the modern concept (i.e.,
substrate consistency, hydrodynamics, turbidity, food resources; MacEachern
et al., 2007 , 2012 ).
Seilacher built the archetypal ichnofacies on a great deal of empirical obser-
vations ( Seilacher, 2007 : 205). Indeed, the ichnofacies concept was chronolog-
ically preceded by contacts with Sch¨fer and H¨ntzschel at the Senckenberg