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
, a working flagstone quarry that is part of the Elk
. 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.