|  This
ichnofossil association of Climactichnites wilsoni and Protichnites
ermita is a rare occurrence at the Blackberry Hill site, with
only a handful of specimens ever having been available. The
dense sandstone plate is loaded with both ichnogenera being
superimposed. These footprints of Climactichnites together
with Protichnites may
be the first animal footprints on land as the makers ventured
out of the water to graze on cyanobacterial mats.
Since
first described by Sir William Logan in 1860, Climactichnites
has remained an enigmatic ichnofossil. The
fossil caused considerable controversy
among paleontologists, and speculation regarding the track maker's
identity abounded. Arthropods with soft bodies were denied by
the lack of footprints. The possibility of a snail was denied
by the V-shaped ridges, and that no known Cambrian snail or worm
(even today) can account for the tracks that can be six or more
inches wide.
Resembling tracks made by a motorcycle both is size and character,
Climactichnites is limited stratigraphically and geographically
to the late Cambrian of North America, before entirely disappearing
from the fossil record.
The
most extensive research on Climactichnites ichnogenera was more
recently conducted by Getty and Hagadorn, to include rigorous
sedimentology
analysis at the Blackberry Hill site in Wisconsin (Elk Mound Group).
They conclude the most likely maker was a Cambrian soft-bodied,
mollusc-like animal reaching more than two feet in length, making
it one the largest Cambrian animals of the time. Locomotion was
by a muscular foot, much like a modern gastropod. A host of sedimentary
evidence (especially raindrop impressions) demonstrate that the
Climactichnites maker inhabited subaerially exposed environments.
Abundant microbial sedimentary  structures associated with Climactichnites
suggest microbial mat binding, together with postulated low levels
of vertical bioturbation would explain trackway preservation.
 In
association here with Climactichnites are Protichnites ichnogenera
trackways, a rare co-occurrence in the quarry. The trackmaker
of Protichnites
at the site is similarly uncertain, and various authors have
proposed eurypterids, horseshoe crabs, euthycarcinoids Aglaspids
or fiddler crabs, or some closely related arthropod or stem group
among these taxons. More recently, Collette, et. al. (2010 and
2012) have described body fossil casts, with legs and segmentation
from Blackberry Hill, and other cladistics and ichnofossil studies
that lends weight of evidence to euthycarcinoid origins to the
Protichnites from Blackberry Hill.
Recent
references:
- Getty, P. R.; Hagadorn, J. W. (2008). "Reinterpretation
of Climactichnites Logan 1860 to Include Subsurface Burrows,
and Erection of Musculopodus for Resting Traces of the Trailmaker".
Journal of Paleontology 82 (6): 1161–1172.
- Getty P. R. (2007)
(masters thesis). Paleobiology of the Climactichnites Trackmaker:
An Enigmatic Late Cambrian Animal Known Only from
Trace Fossil
- Collette,
J. H., K. C. Gass & J. W. Hagadorn (2012). "Protichnites
eremita unshelled? Experimental model-based neoichnology and
new evidence for a euthycarcinoid affinity for this ichnospecies".
Journal of Paleontology 86 (3): 442–454.
- Collette,
J. H. & J. W. Hagadorn (2010). "Three-dimensionally
preserved arthropods from Cambrian Lagerstatten of Quebec
and Wisconsin".
Journal of Paleontology 84 (4): 646–667.
- Hagadorn,
J. W., and A. Seilacher (2009). "Hermit arthropods
500 million years ago?". Geology 37 (4): 295–298.
- More
references
Also
see: Cambrian
Shadows Climactichnites Protichnites World's
Best Climactichnites |
