ABSTRACT
The difculty of assigning truly unique trace fossils to the activities of specic organisms is epitomized by Yochelson and Fedonkin’s (1993) detailed account of the Late Cambrian form Climactichnites (Figure 141 and Figure 142). This form has been considered to reect the activities of varied, unrelated major animal groups but still remains difcult to assign. Knox and Miller (1985) provided illustrations and a description of the trace produced by the modern carnivorous gastropod Polinices in loose, upper intertidal sand. Although it is one-third to one-quarter narrower than typical Climactichnites, it is remarkably similar in most respects; one wonders whether an unshelled gastropod is responsible for the Late Cambrian enigmatic trace. The trace fossil Plagiogmus is also similar (see MacRae, 1999, p. 3), and similar uncertainty obtains as to its maker. Getty and Hagadorn (2008) provided excellent illustrations of Climactichnites from New York, Wisconsin, and Missouri while describing a presumably shallow burrowing “relative”; they suggested that a molluscan or “mollusk-like” animal was probably responsible for these unique trace fossils.
