Thalassinoides-Phycodes compound burrow systems in Paleocene deep-water limestone, Southern Alps of Italy

Compound burrow systems, consisting of branching, horizontal tunnels in the core areas of the systems intergrading with fan-like tunnels in distal areas, are common in the Paleocene Scaglia Cinerea limestone. If preserved as isolated elements, the cores would be identified as Thalassinoides suevicus and the distal elements as Phycodes cf. palmatus. These complex trace fossils are probably combination dwelling-deposit feeding structures produced by endobenthic crustaceans that occupied and ‘operated’ the systems for relatively long intervals of time. Compounds such as these may be more common than supposed and represent an important, but essentially unexploited, source of biologic information on marine invertebrate trace producers.