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748 Alfred Uchman, Andrzej Ślączka and Pietro Renda

Fig. 3. Faviradixus robustus sp. nov. in Lower Pleistocene calcarenites of Punta Lungo, site 1

A – holotype before its excavation, view from the top; B – several tubular structures in large-scale cross-bedded calcarenites, side view; C – converging-up
tubular structures, view from the top; D – coalescing tubular structures converged in a central area, Ophiomorpha nodosa (Oph), view from the top; E –
branched tubular structures of different sizes, oblique view; F – cross-section with a distinct “wall”

D i s c u s s i o n. – The upwards convergence, spreading inating by diagenetic cementation. The off-centre position of
out from one point (see Sarjeant, 1975), oblique dichotomous the lumen is typical of the other named root structure
branching down, the smaller size of some branches and, a ten- Rhizoichnus D’Alessandro and Iannone, 1982. The tube was
dency to self avoidance suggest interpretation of F. robustus as filled passively by calcarenitic sediment, maybe due to filling
side roots of a large plant, probably a tree. Many tree roots of voids by marine sediment after the roots decayed. Rare
show a similar pattern (Fig. 7). The “wall” (Fig. 5A) is not a cross-overs, including “tube-in-tube” occurrences, can be ex-
constructed wall sensu Bromley (1996), which is typical of ani- plained by penetration of a living root into a dead one. Co-oc-
mal burrows, but rather a root tubule sensu Klappa (1980) orig- currence with marine animal trace fossils is possible because