Fluvial Environments - Trace Fossils as Indicators of Sedimentary Environments - page 334

( Loloichnus ), meniscate burrows ( Beaconites ), large vertebrate burrows,
perforations in the wall of other trace fossils ( Lazaichnus , Tombownichnus ),
and rhizoliths ( Fig. 1 B). These assemblages ( n

4) display a moderate average
ichnodiversity (9 trace-fossil morphologies) and are essentially produced
by insects, crayfishes, plants, and tetrapods. The Coprinisphaera Ichnofacies
characterizes paleosols developed in paleoecosystems of herbaceous communi-
ties, particularly grass-dominated habitats ( Genise et al., 2000 ).

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3.3 Ichnofacies

The recently proposed Celliforma Ichnofacies is found in calcretes and
carbonate-rich paleosols developed in palustrine carbonates. It is typified by a
recurrent association of insect trace fossils produced by bees and wasps, partic-
ularly Celliforma , Cellicalichnus , and Rebuffoichnus ( Genise et al., 2010 ). At
least six fluvial trace-fossil assemblages can be assigned to the Celliforma Ich-
nofacies (e.g., Martin and Varricchio, 2011; Retallack, 1984 ). As with the Copri-
nisphaera Ichnofacies, the dominant trace-fossil morphology is formed by
chambers and chambered burrow systems (e.g., Cellicallichnus , Celliforma ,
Rebuffoichnus , Teisseirei , Fictovichnus , Pallichnus ; see Fig. 3 F). Secondary
components are rhizoliths (including shallow networks and taproots of
medium-sized plants and trees); burrows and chambers with pelletal fill
( Edaphichnium ); J-, U-, or Y-shaped burrows ( Macanopsis ); vertebrate copro-
lites; and large vertebrate burrows ( Fig. 1 C). These assemblages can be distin-
guished from those assigned to the Coprinisphaera Ichnofacies by the
dominance of Celliforma , Rebuffoichnus , and Cellicalichnus , and by a lower
ichnodiversity. The Celliforma Ichnofacies would be indicative of a drier cli-
mate and lower vegetation coverage than those represented by the Coprini-
sphaera Ichnofacies, particularly for scrubs and woodlands ( Genise et al., 2010 ).

Celliforma

3.4 Ichnofacies

The original proposal of the Termitichnus Ichnofacies ( Smith et al., 1993 ) was
revised by Genise et al. (2000) , who suggested it to be retained for assemblages
dominated by termite nests in paleosols of closed forest ecosystems under warm
and humid conditions. Although this ichnofacies is potentially distinctive, only
a few cases are known at present, including three from fluvial settings ( Fig. 1 D).
The best known case study concerns the Oligocene-Miocene Jebel Qatrani For-
mation of Egypt ( Bown, 1982; Genise and Bown, 1994 ), and other possible
examples are the Plio-Pleistocene Upper Siwalik Subgroup of India (“ichno-
facies D” of Tandon and Naug, 1984 ) and the Pleistocene-Holocene Orange
River deposits of South Africa ( Miller and Mason, 2000 ). These assemblages
also display a dominance of chambers and chambered burrow systems
( Termitichnus , Krausichnus , Vondrichnus , Fleaglellius , Masrichnus ; see
Fig. 4 A and B), J-, U-, or Y-shaped vertical burrows ( Macanopsis ), rhizoliths,
large vertebrate burrows, and burrows with pelletal fill ( Edaphichnium ).

Termitichnus