Blackerry Hill Ichnofossils


Fossil Dealer: Stone Relic

Also see: Cambrian Shadows

These ichnofossils are from a site that may shed light on one the least known aspects of the evolution of life on earth, the colonization of land by animals during Paleozoic Time. Ichnofossils of the Cambrian are paramount to ongoing research because they may elucidate animal behavior as well as animal morphology. The peer-reviewed literature already supports transition to land by amphibious arthropods during the Lower Ordovician, and now ongoing research into a diverse Ichnofauna from Central Wisconsin may push the date of this evolutionary milestone to the Upper-Middle to Upper Cambrian.

They come from the Krukowski quarry, a working flagstone quarry that is part of the Elk Mound Group. Ichnofossils occur in quartz sandstones that sometimes exhibit wave- and wind-induced ripples and trough cross bedding, rain drop imprints, and a total absence of any shelly animals as if locked in a evolutionary time warp where time stood still. All evidence is indicative of a an ancient intertidal, marginal marine (subaerial) environment, in which the ichnofossils were formed.

There is a large diversity of ichnogenera, including madusoid and tentacle Scyphozoa Cnidarians (jellyfish) impressions; arthropod trackways both without (Diplichnities sp.) and with (Protichnites) tail drag marks, the enigmatic Climactichnites, resembling a motorcycle tire print that was studied by Walcott himself in the 1800s, and, most recently, carapaces of the putative arthropod track maker that resemble the enigmatic Euthycarcinoids or Aglaspids, as well Rusophycus, the potential resting place of the arthropods. All aspects of this fossil site are undergoing intense study, with much anticipated publications.

The jellyfish ichnofossils were probably the outcome of mass stranding, while the arthropod ichnofossils could well be the oldest footprints in the fossil record, when life was first venturing on to shore. To learn more about these ichnofossils and the site, link to the Cambrian Shadows theme park. Click here to learn more about ichnofossil nomenclature.

Arthropods: Protichnites, Diplichnites, Euthycarcinoid or Aglaspid and Rusophycus

Protichnites & Diplichnites Ichnofossils Association