Coming from the Cambrian-age Krukowski quarry in central Wisconsin, this ichnofossil combines two inchnogenera, Diplichnites with Protichnites, that may well represent some of the earliest animal footprints on land. When these footprints were made, what is now Wisconsin was some 10 degrees below the equator, and paleontologists believe the site was once a beach of a shallow marine environment.

No shelly animals are found in the Krukowski quarry, only trackways (Ichnofossils) and body impressions (such as in the case of the Jellyfish (Cnidarians). Besides a few mysterious trackways that cannot be named, one finds Diplichnites, Protichnites and Climactichnites. Together, this quarry tells a story just now being researched by paleontologists - hopefully, the result will be some shedding of more light on when and how life ventured from marine to land environment.

Popular conjecture is that generic Diplichnites is the trace of a arthropod, such as wandering Myriapoda, which brings to mind an ancient centipede (Chilopoda). Protichnites is a generic genus of trace fossil that are the imprints made by the feet of walking arthropods. These fossils are normally found in what were shallow-water areas and tidal zones of Paleozoic shorelines, and are also known from the Cenozoic fossil record. There is an enormous diversity of arthropods that could have been responsible for Protichnites; In terms of the upper cambrian Krukowski quarry, putative trackmakers include Euthycarcinoids, Aglaspids, and eurypterids. The Protichnites ichnogenus comprises two approximately parallel rows footprints together with a longitudinal depression, normally between footprint rows. The depression can be constant or piecewise dashes, and is considered to be the consequence of a dragging body appendage such as a telson (tail). Diplichnites is like Protichnites, but absent the tail drag tracks.

The maker of the Protichnites fossil trackways might have been an animal resembling the extant but ancient horseshoe crab, except of an early design that lacked a hard shell to be preserved. Others have posited that Protichnites was a soft-bodied progenitor of the large, now extinct group of early predators, the Eurypterids (Chalicerate "biting claws" Arthropods).

It is also possible that the same animal made both type of tracks, depending on behavior, locomotion, feeding behavior or even tide level - and so continues the mystery of these ichnofossils.

This large specimen has a mryiad of footprints, footdrags or slashes, and tail drag marks left in the Cambrian-age sand. Interestingly, the specimen contains a gradient of track densities, with an extraordinarily high density (tracks upon tracks) of both Diplichnites and Protichnites tracks in the upper left. The upper left is suggestive of some kind of frenzied behavior, be it feeding, mating or other. To the down and right, the density of tracks diminishes, and the Protichnites tracks are absent. There has been no staining of this hyperrelief specimen. Also note the prototypical shoreline sand ripples that are common for many of the Krukowski quarry ichnofossils plates.

Also see: Cambrian Shadows Theme Part