Museum Climactichnites wilsoni and youngi Cambrian Ichnofossils

This unique Cambrian inchnofossil comes out of a sandstone formation recently dubbed Blueberry Hill in Central Wisconsin that was once a tidal beach, resulting in the distinctive ripples you see on the matrix surface. At present, it is generally accepted that the age of this sandstone unit is upper Cambrian and thus represents an outlier of the Mount Simon Sandstone. This quarry has been producing some intriguing trace or ichnofossils, including huge madusae, tentacled jellyfish, Diplichnites, Protichnites, and the Climactichnites ichnogenus you see here, among others.

The depositional environment in this quarry varies from very shallow marine to aerial. This is very significant as the ichnofossils from this locality may be the earliest evidence of large organisms and carnivores abandoning their marine habitat to utilize the terrestrial environment. These ichnofossils may pre-date the Cambrian-Ordovician trackways from Canada just described in the May 2002 issue of Geology.

Climachtichnites has been described as looking like the track of a motorcycle that drove across rippled sand. The ripples in the sandstone confirm that the layer is a bedding plane that was once a Cambrian intertidal zone. If Climachnichnites is a trackway, the traverse ridges can be viewed as made by muscular undulation as the animal motivated through the sand above the water. Also note the ridges on the margins on the tracks, the same as the ridges that build on either side of blade of a bulldoser. One theory of Climactichnites is that it was made by a large slug, others believe a mullusk, and still others posit an animal in an unknown Phylum that did not survive much beyond the Cambrian. There are two described inchnogenera, Climactichnites wilsoni that has paired lateral ridges between which are undulating bars and furrows oriented at an angle to the direction of travel, and Climactichnites youngi that lacks the paired lateral ridges and has only of undulating transverse bars and furrows

This particular specimen is one of the largest Climactichnites fossils to become available from the Krukowski quarry, where collecting is no longer permitted. There are two straight Climactichnites wilsoni trackways converging from one end to the other. They overlay and diagonally cross a Climactichnites youngi trackway. It took several hours with a gas-powered, diamond blade saw to cut this fossil down to its current size, and that does not include what it took to originally cut it out of the quarry floor.