Treptichnus bifurcus Miller, 1889

Emended diagnosis. Subhorizontal burrow consisting of a series of U-shaped segments joined angularly at or near their ends; burrow commonly but not invariably zigzag; surface of burrow smooth.

Diagnosis.—Burrow system with short projections between elongate, thin, and horizontal burrow segments forming straight to slightly curved, zigzagged chains; may occur as chains of evenly spaced beads or depressions alternating around central axis, forming zigzag pattern (Buatois & Mángano, 1993a; Uchman, Bromley, & Leszczyński, 1998).

Diagnosis: Treptichnus having short twiglike projections at the angle of juncture between elongated, horizontal and thin burrow segments; projections situated on alternate sides of trace, representing bedding plane expressions of oblique shafts (modified from Maples and Archer, 1987).

Diagnosis: Treptichnus having short, twiglike projections at the angle of junction between elongated, horizontal and thin burrow segments; projections situated, as determined by the zigzag, on alternate sides of the trace fossil (modified from Maples and Archer, 1987; Buatois and Mângano, 1993).