Description:
The collector of this unusual fossil thinks it has strong affinities
with the lobopodian Hallucigenia. While no legs are preserved, material
form the Weeks often does not have them present. It does indeed
have a similar profile, particularly to the “head”.
Whatever it is, it is a most enigmatic fossil, and the first I have
ever seen.
The
House Range of Utah has several formations that exhibit Burgess
Shale-like preservation of soft tissues, and yield fossils of
creatures
closely allied with the Burgess Shale biota. Interestingly, the
formations are normally found in alternating biofacies. Some
are
rich in trilobites lacking soft bodied organisms, while adjacent
ones lack trilobites but preserve soft bodied organisms in the
form
of kerogenized carbon films. Gaines (2004) has studied the taphonomy
of House Range soft tissue preservation, hypothesizing a taphonomic
pathway much like the Burgess Shale with delayed decay facilitating
rapid diagenesis in an anoxic zone lacking benthic bioturbators.
While soft bodied organisms are far rarer and generally not so
exquisitely
preserved as in the Burgess Shale, some scientists believe the
House Range biota might be even more diverse. Many fossils found
are enigmatic
as to their taxonomic placement. Unfortunately, the numerous sites
are much understudied, while mining operations are resulting
in
wholesale destruction of a potentially rich portion of the Cambrian
fossil record.
References:
- Briggs
D.E.G., and R.A. Robison. 1984. Exceptionally preserved non trilobite
arthropods and Anomalocaris from the Middle Cambrian of Utah.
University of Kansas Paleontological Contributions, Paper 111:1-24.
- Gaines,
Robert R.; Kennedy, Martin J. Droser, Mary L. 2004. A new hypothesis
for organic preservation of Burgess Shale taxa in the middle Cambrian
Wheeler Formation, House Range, Utah. Palaeo, 220:193-205.
- House
Range Fossils: Wheeler Shale, Marjum Formation, and Weeks Formation,
The Virtual Fossil Museum (www.fossilmuseum.net).
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