Enigmatic Animal Fossil from the Cambrian Explosion

Animalia, Incertae sedis

Geologic Time: Upper Middle Cambrian

Size: 30 mm

Fossil Site: House Range, Weeks Formation, Millard County, Utah

Enigmatic Cambrian FossilThe understudied House Range of Utah yields numerous fossils that are enigmatic, and this is one of them. Notice the cursory resemblance to the spindle with skewers used to hold sweet corn, earning it the colloquial name "corn cob holder”. There is marked annulation to the body, and the spikes at the end (which end, front or back?) are also quite evident. The House Range is one of the world's Burgess Shale like Lagerstatten, though this is not well known. Whatever this animal is, it exhibits soft-tissue preservation like the Burgess Shale and Chengjiang.

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 addition to the Cambrian fossil record.

Image credit (CC BY-NC 4.0)


  • 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.

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