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754 Alfred Uchman, Andrzej Ślączka and Pietro Renda

Fig. 11. Other trace fossils from the sites studied (top views of horizontal surface)

A – Ophiomorpha nodosa with the pelleted wall and a partly meniscate filling, horizontal; B – Ophiomorpha isp.; C – Faviradixus robustus (Fa) and
Ophiomorpha nodosa (Oph); D, E – Beaconites isp.; F – Thalassinoides isp.

Thalassinoides isp. (Fig. 11F) consists of horizontal, animal burrows. Crustacean burrows rather form mazes or
branched, tubular burrows, which are 3–6 cm wide. Trace fos- boxworks, with swellings, especially at where branches join.
sils of this ichnogenus are produced mostly by decapod crusta- These features suggest plant roots, the taphonomy of which is
ceans (Frey et al., 1984; Ekdale, 1992) in several marine, poorly understood, while classification in the fossil record is
mostly shallow-water environments. underdeveloped. Therefore, with hesitation, we interpret them
as plant root structures.
Beaconites isp. (Fig. 11D, E) is a gently winding, horizon-
tal burrow, 55 mm wide, with a thick wall-like structure that is Faviradixus robustus and Egadiradixus rectibrachiatus are
up to 8 mm wide. It is filled with crudely meniscate sediment as structures that deeply penetrate marine deposits containing ma-
in the surrounding rock. This trace fossil displays features of rine macrofossils and trace fossils. They penetrated from conti-
the ichnogenus but does not fit to the known ichnospecies of nental surfaces, which are not preserved at the sites of their oc-
Beaconites, which can occur in non-marine and shallow-ma- currence. The surfaces were high enough to keep the water table
rine sediments (see Keighley and Pickerill, 1994). at a depth of at least 1.5–2 m, allowing the roots to live in
well-oxygenated ground. In the case of a shallow water table,
DISCUSSION roots are short, thick and iron minerals are abundant (Sarjeant,
1975; Arndorff, 1993; Pieńkowski, 2004). Good oxygenation of
Faviradixus and Egadiradixus resemble large crustacean the substrate is probably responsible for absence of the carbon-
burrows, but the similarity is apparent. Both of them display at ized lining. Deep roots, up to 3.5 m long, penetrating deposits
least parts of branches, with dimensions smaller than the master with marine trace fossils, are known from the Pleistocene depos-
tube and strong self avoidance. Neither form displays a granu- its of the Tyrrhenian Sea coast (D’Alessandro et al., 1993).
lated wall or a meniscate filling, which are typical features of
Egadiradixus rectibrachiatus penetrates a cross-bedded
coarse calcarenite, upper part of which (30–40 cm) is