Ichnotaxonomy: Finding Patterns in a Welter of Information - Trace Fossils as Indicators of Sedimentary Environments - page 68

as shown by its DNA. In the absence of an objectively determined classification,
can such a hierarchy be useful for traces and trace fossils?
Nothing in the ICZN prevents such classification ( Rindsberg, 1990 ). The
ICZN governs only the formal ranks of species, genus, and family, together with
subdivisions such as subspecies, superspecies, subgenus, supergenus, subfam-
ily, and superfamily, as well as others that we need not consider here. (Inciden-
tally, because the Code does not apply to higher taxa, it is possible for different
researchers to use alternate names for the same taxon, for example, Bivalvia,
Pelecypoda, and Lamellibranchiata. The fact that it is possible, however, does
not make it a good idea.)
The use of ichnofamilies and higher ichnotaxa has, in fact, already been
applied to traces of vertebrate and invertebrate origin. In the case of vertebrate
ichnology, a relatively stable classification is possible because of the complex-
ity of characters, which commonly allow recognition of a clade of tracemakers,
and it is far preferable to maintain a higher classification of vertebrate trace fos-
sils than to shoehorn them into the classification of tracemakers.
In the case of invertebrate trace fossils, no one higher classification has
taken hold. Though it can be argued that no higher classification of such traces
is theoretically possible, the fact is that researchers have repeatedly attempted
such classifications and that some of the categories they have proposed are
useful. One of the best approaches toward an eventual consensus is that of
Ksi˛˙kiewicz (1977) and Uchman (1995, 1998), whose papers on flysch trace
fossils have gradually refined morphological categories over a period of time
without formal designation as ichnofamilies. By grouping similar forms rather
than listing them alphabetically, Uchman (1995 ) was able to show comparisons
among trace fossils that represent related behaviors. These morphological
groups include an Ophiomorpha group ( Ophiomorpha, Thalassinoides,
Psilonichnus ) , a Scolicia group ( Scolicia, Bichordites ), a Glockerichnus group
( Glockerichnus, Capodistria ), and others. By using informal but named groups,
he allowed discussion to continue while avoiding unnecessary taxonomic
debates.
7.6 Ichnosubspecies and other Subdivisions
In another direction, it is occasionally helpful in ichnotaxonomy to utilize finer
subdivisions, such as subspecies. As in the case of ichnofamilies, the ICZN
allows the use of any established biological rank as an ichnological rank as well.
The prefix ichno - is added to make the distinction clear, for example, ichnosub-
species (not “subichnospecies”). According to the ICZN, the naming of a spe-
cies, genus, or family automatically generates a series of subdivisions
(subspecies, superspecies, subgenus, and the rest), all of which share the same
type, are attributed to the same author, and are assigned the same date. Very few
such ichnotaxa have been named, and only within relatively well-studied ich-
nogenera. Examples include ichnosubspecies named in Arthrophycus and