The newly discovered trace fossil is a boring that extends from the colony surface through a portion of the interior (endozone) of the bryozoan colony, oriented approximately along the axis of growth.  The unlined boring, which served as a dwelling (domichnium), was enlarged by the boring organism as it grew.  Both straight and branching burrows were produced.  The cavity produced has a single opening.  Size of the traces varies from 3.0mm to 8.8mm wide and 9.7mm to 53.0mm long.  Larger sizes are probable because a majority of the bryozoan samples we have studied have been broken branches that truncate the trace fossil.  This indicates that traces longer then 5cm occurred frequently.

We believe it most likely that the boring was made by a marine annelid worm as a dwelling place.  The single opening, which would have restricted the development of a feeding current through the burrow, suggests the occupant was a suspension feeder that extended its feeding organ beyond the opening of the burrow.  Occurrence of these borings in upright rather than in bottom-encrusting bryozoan colonies suggests that the organisms were using suspended food particles well above the bottom.  By feeding in a higher tier, the organism removed itself from competition with many bottom dwelling suspension feeding organisms on the Cincinnatian sea floor.  Position high in a colony potentially placed the organism in competition with host bryozoan polypides plus a variety of epizoans that may encrust the surface of the colony.  These encrusters could include species of Cornulites, Trypanites, Cuffeyella, and other Bryozoa.  We suggest that, because the opening of the burrow is larger than the diameter of the openings of any of these encrusters, the organism was likely larger than any of it competitors and likely feed upon larger suspended particles, thus partitioning food resources.  This living position allowed the borer to take advantage of both ambient water currents and the feeding currents generated by the host colony.  The organism retracted when not feeding or for protection.

There are no known ichnospecies with the morphology and paleoecology described above.  The most common ichnogenus in the Cincinnatian hardground was Trypanites (Magdefrau 1932).  Bromley¹ redefined that ichnogenus in 1972, as a single-entranced, unbranched, pouched-shaped borings.  Kobluk and Nemcsok² gave Trypanites burrow opening sizes ranging from 0.35mm to 1.9mm and burrow lengths ranging from 3mm to 25mm.  The burrows we are describing are considerably larger then those of Trypanites and frequently branched.