Diagnosis.—Chains of horizontal to subhorizontal, straight to curved, zigzagging burrow segments associated with vertical to oblique tubes producing a three-dimensional burrow structure; pits and nodules may occur near top or base of burrow segments at sediment interfaces (Buatois & Mángano, 1993a; Uchman, Bromley, & Leszczyński, 1998).
Remarks.—Treptichnus is interpreted as a fodinichnion made by vermiform animals (Buatois et al., 1998). Recent neoichnologic work has convincingly argued for a priapulid origin for Treptichnus pedum (Vannier et al., 2010). Originally described as Phycodes pedum (Seilacher, 1955), Jensen (1997) referred this ichnospecies to Treptichnus whereas Geyer and Uchman (1995) placed it in Trichophycus. The type specimen (Seilacher, 1955, p. 387, fig. 4a) shows branching at the end of the burrow system resulting in a sickle-shaped appearance. Jensen (1997) included more irregular branching patterns with curved to highly winded courses and alternating or single sided segments. The proposal by Jensen (1997) became generally accepted (e.g., Seilacher et al., 2005; Seilacher, 2007; Vannier et al., 2010). Although the scarcity and incomplete nature of the Hanneh specimens prevent from a definite assignment, the overall morphology corresponds with descriptions by Jensen (1997
Diagnosis: Chains of zigzag, straight or curved burrow-segments associated with vertical or oblique tubes comprising three-dimensional structures. Unbranched, except wheresegments diverge from each other, at which places small pits or twig-like projections occur (modified from Buatois and Mângano, 1993).
Ethology. Treptichnus has been interpreted as both a feeding structure (Seilacher and Hemleben, 1966; Häntzschel, 1975; Rindsberg, 1990) and a farming trace (Rindsberg,1990), probably produced by vermiform animals.Treptichnus represents an eurytopic form of behavior; the trace has been recorded from lacustrine (Archer and Maples, 1984; Buatois and Mángano, 1990a, b), brackish tidal flat (Rindsberg, 1990), shallow-water marine (Banks, 1970; Fedonkin et al., 1983; among many others), bathyal (Seilacher and Hemleben, 1966), and submarine fan environments (Crimes et al., 1981). Although of little use at the ichnogeneric level, some ichnospecies of Treptichnus seem to be useful as environmental indicator.