Planolites beverleyensis (Billings, 1862)

Diagnosis. Relatively large, unlined, smooth, horizontal to undulant, straight to sinuous, cylindrical burrows. The filling typically
differs in colour from the surround ing sediment (Frey and Bromley, 1985).

Description.—Subcylindrical to cylindrical, horizontal vermiform structures with irregularly constricted surface, predominantly preserved as positive epirelief and hyporelief (Fig. 7.7). Width is 1 to 4 mm. Course is irregular, gently curved, or arcuate. Overlap among specimens is common. Fill is coarser-grained than the host rock.

Remarks.—The constrictions clearly point to an active infill. Deposit feeding was mostly constrained to an interfacial sand-mud boundary. Planolites beverleyensis differs from Planolites montanus in its curved to arcuate courses and more penetrative nature (Pemberton and Frey, 1982)

Straight, moderately to conspicuously curved, smooth, exceptionally branching tunnels of circular outline, parallel to oblique to the bedding, preserved as full reliefs or convex hyporeliefs. Diameter of tunnels ranges usually from 2 to 6 mm; length of preserved sections may reach few decimetres. Tunnels present on one bed or bedding plane show usually a constant diameter.

Predominantly cylindrical, smooth-walled, rarely toirregulerly branched or unbranched burrows, typically oriented more or less parallel with bedding. Some specimens are terete, and may exhibit slight distentions; most are cylindrical and straight toarcuate over appreciable lenghts. Rare specimens display discontinuous, poorly developed annulations. Occurenses range from single, isolated specimens to crowded masses in which crossowers, interpenetrations, and reburrowed segments are commen. Burrow density and substrate characteristics may modify burrow configurations. Preserved as endichna, hypichnal ridges, and epichnal grooves.

Burrows cylindrical to flattened, with smooth walls, straight to slightly curved, very regular with insignificant variations in shape or diameter. They occur either isolated or densely cover bedding surfaces, overlapping each other. Their diameter ranges from 4 to 8 mm, length reaches up to 9 cm. Sometimes they occur within the sandstone bed being infilled with clay and differing in colour from the host rock; occasionally they remain empty. Convex epireliefs.