Taenidium barretti (Bradshaw, 1981)

Discussion.—Taenidium barretti is the only ichnospecies with the menisci not grouped in compartmentalized packets. The menisci are thin segments, hemispherical or deeply arcuate and tightly stacked (Keighley and Pickerill, 1994). In the original definition of T. barretti, Bradshaw (1981) noted that the horizontal sections are commonly joined by short vertical tunnels.

Ethology and tracemaker.—Taenidium barretti is a locomotion trace (repichnion) and/or a feeding structure (fodinichnion). Meniscate fill is an active backfill that results from mechanic manipulation or ingestion by the animal (e.g., Buatois and Mángano, 2011). On one hand, meniscate fill is produced by an animal that passes material along the sides of its body and compact it behind them by forward motion but with few evidence of ingestion (Bradshaw, 1981) and commonly produced by locomotion of insects (Frey et al., 1984b; O’Geen and Busacca, 2001; Gregory et al., 2004). On the other hand, Taenidium barretti may involve ingestion and excretion of an animal that transports the sediment through the body as it has been associated with deposit or detritus feeding organisms, most likely worm-like organisms (Bown and Kraus, 1983; Squires and Advocate, 1984; D’Alessandro et al., 1987; Sarkar and Chaudhuri, 1992; Schlirf
et al., 2001).

T. barretti (Bradshaw, 1981), typical of continental deposits, is much larger, with hemispherical to deeply arcuate menisci, commonly filled with coarser material.

Emended diagnosis. Straight to variably meandering, unbranched, unwalled, meniscate backfilled burrow. Menisci are commonly hemisphaerical or deeply arcuate, tightly packed or stacked, forming non-compartmentalized backfill or thin meniscate segments.