Rosselia socialis : a dwelling structure of a probable terebellid polychaete

Abstract

The trace fossil Rosselia socialis Dahmer 1937 is a funnel‐shaped structure characterized by a concentrically laminated wall having a narrow cylindrical shaft at the central portion. In association with well‐preserved funnel‐shaped R. socialis, many spindle‐shaped R. socialis‐like specimens are abundant in the Middle Pleistocene Kongochi Formation in central Japan. While the former always occur just below an erosional bedding plane or outcrop surface parallel to the bedding, the latter are found in sediment showing no breaks in sedimentation. This suggests that the funnel‐shaped ‘R. socialis’ is actually the truncated lower part of the spindle‐shaped structure. In one specimen, deformation of laminae appears to have formed synchronously with construction of the wall. Morphology of the structure strongly suggests that the wall of R. socialis was formed through outward expansion caused by accretion of muddy material at the inner surface of the wall by the trace‐maker inhabiting the central burrow. A specimen that was covered by a volcanic ash has the wall made up of the ash. This indicates that the maker of the burrow utilized surface sediment to construct the wall; that is, the trace‐maker was possibly a detritus feeder. The terebellid polychaetes are reasonable candidates for the trace‐makers. □Rosselia socialis, Japan, Middle Pleistocene, trace fossil, trace‐making process, trace‐maker.

Paleoecologic and Biostratigraphic Significance of Trace Fossils From Shallow- to Marginal-Marine Environments From the Middle Cambrian (Stage 5) of Jordan

“…Several studies have documented variable morphologies of Rosselia in response to sedimentation events (e.g., Nara, 1997Nara, , 2002Pemberton et al, 2001;Campbell et al, 2006). In a pioneer study, Nara (1995Nara ( , 1997 described funnel-and spindle-shaped specimens of Rosselia which are vertically stacked reflecting upward migration to avoid burial due to episodic sedimentation in a storm-dominated shallow-marine setting. Pemberton et al (2001) illustrated stacked funnel-shaped Rosselia as a response of storms in a lower shoreface.…”

“…Rosselia socialis represents a dwelling structure of detritusfeeding organisms and terebellid polychaetes have been suggested as tracemakers in younger examples (Nara, 1995(Nara, , 2002.…”

Biology of shallow marine ichnology: a modern perspective

“…In some burrows, the lining is observed to be extravagantly over-thickened, typically with fine-grained clastics. This is commonly accompanied by a flaring of the lining, producing the spindle-shaped lining commonly observed in terebellid polychaete burrows (Aller & Yingst 1978, Nara 1995, Gingras et al 1999, or a drum-shaped morphology (Wetzel & Bromley 1996). Flared or tapered structures in the rock record would be described as Cylindrichnus or Rosselia (Figs.…”

Rosselia socialis in the Upper Marine Molasse of southwestern Germany

“…Following the original description, the taxon has been recorded worldwide in sediments ranging from the Lower Cambrian to Pleistocene. R. socialis is characterized by funnel-or spindleshaped burrows oriented obliquely to roughly perpendicular to the bedding planes, with a length usually varying from 30 to more than 100 cm and a diameter between 0.5 and 16 cm (Schlirf et al 2002;Nara 1995Nara , 2002Krenmayr 1995, 2004;Campbell et al 2006); the longest specimens are stacked forms up to 170 cm long (Nara 2002). The central portion of the burrow consists of a narrow cylindrical shaft, which appears as a small and occasionally slightly excentric wart on weathered bedding planes.…”