INTRODUCTION

The Coste dell'Anglone ichnosite is located along the eastern slope of Monte Brento (Dro, Trentino Alto-Adige, NE Italy; Figure 1), in the central-eastern sector of the Southern Alps, slightly north of the Lake Garda. In this site, hundreds of dinosaur tracks, mostly arranged in long trackways, were recognized on a wide surface dipping about 30° SE, representing the flank of a ramp anticline associated with the main E-oriented thrust (Petti et al. 2008, Petti et al. in press).

Immediately below the dinosaur trampled bed, several Asteriacites lumbricalis traces were found (see also Bernardi et al. 2010). Asteriacites von Schlotheim, 1820 is a well known star-shaped resting trace (cubichnia) that belongs to the Cruziana ichnofacies (Seilacher 1964, 1967). In wave-dominated systems this ichnofacies is often present in the region between daily wave base and storm wave base (Frey and Pemberton 1985, but see Frey et al. 1990) while in tide-dominated environments it may also occur in intertidal positions, grading seaward into the Skolithos ichnofacies (see discussion in Mangano and Buatois 2004). Asteriacites has a long temporal range extending from Cambrian to recent shallow- to deep-marine facies (see Mikuláš 1992 and references therein). In the Eastern sector of the Southern Alps, Asteriacites has been documented several times (e.g., Broglio Loriga et al. 1983, 1990), and its occurrence has in particular been investigated in the study of the Permo-Triassic aftermath (e.g., Twitchett and Wignall 1996; Wilson and Rigby 2000).

Seilacher (1953) suggested that Asteriacites lumbricalis was probably made by ophiuroids but most subsequent papers did not provide any discussion about the possible producer of the trace (but see Spencer and Wright 1966; Lawrence 1987; Wilson 1997). The tracemaker was generally intuitively indicated as a member of the Asterozoa without distinguishing between asteroids and ophiuroids (e.g., Santos and Campanha 1970; Brito 1977; Crimes and Jiang 1986). However, Mángano et al. (1999) convincingly showed that an ophiuroid tracemaker is the most reliable interpretation in the majority of cases. Mikuláš (1990) and West and Ward (1990) have also provided evidence of Asteriacites lumbricalis preserved with ophiuroids remains.