Thalassinoides bacae Ekdale et Bromley, 2003

Ichnospecific diagnosis: Dominantly horizontal Thalassinoides with numerous, closely spaced, short, vertical shafts aligned along the horizontal tunnels.

Description: Tunnel diameter is generally 4–6 mm, and the distance between branch points is highly variable. Tunnels may be curved or straight, and they commonly run along the outer margins of orthocone cephalopod shells. Shaft diameter is generally 4 mm, and shaft length is 1–2 cm. Shafts are straight and perfectly vertical. Tunnel and shaft walls are prominently displayed (colored darker than the host sediment) by extensive secondary mineralization.

Remarks: Thalassinoides bacae most closely resembles T. horizontalis Myrow, 1995, which was described from Cambrian and Ordovician strata in Colorado. The main difference between the two ichnospecies is the presence of numerous, prominent, vertical shafts in T. bacae, which are entirely absent from T. horizontalis