Burrows of the giant beach worm (Australonuphis) in a high-energy beach environment in New South Wales, Australia: implications for the palaeoecology of some Phanerozoic Skolithos assemblages

The trace fossil Skolithos is a simple, sub-vertical, unbranched, cylindrical burrow that characterizes the trace fossil from early Cambrian to recent times. The Skolithos ichnofacies is an indicator of high-energy coastal marine facies, such as the sandy beaches of wave-dominated coasts; however, to date, neoichnological studies have only reported its occurrence in low-energy settings, where it is produced by a variety of annelids, phoronids, and priapulids. In this paper, we describe the burrow produced by the Australian giant beach worm ( Australonuphis , family Onuphidae) at Bengello Beach, southeastern Australia, where they occur in a high-energy, wave-dominated sandy coastal setting. The burrows of this omnivorous scavenger show a straight or slightly bent vertical shaft without branching or chambers, and may be regarded as a modern analog of the trace fossil Skolithos. The burrows are distributed only below the lower foreshore, and therefore we infer that the uppermost level of Skolithos occurrences in the Phanerozoic fossil record may be a useful indicator of ancient sea-level in the Skolithos ichnofacies. As such, our findings improve knowledge of the palaeoecology of the Skolithos ichnofacies, including feeding ecology, and enhance its palaeoenvironmental utility. • The Australian giant beach worm produces a simple but long vertical burrow. • The burrow has the same feature as the trace fossil Skolithos . • The burrow occurs only below the lower foreshore. • The trace fossil Skolithos can be used as an indicator of ancient sea level.