Produced by the Population Genetics and Evolution class, Furman University

The Cambrian: Protichnites
Protichnites are a type of ichnofossil, or "trace fossil" that have been found in numerous sites across North America as early as the 1850s (MacNaughton and Hagadorn 2006). These imprints originate from the Cambrian period, usually comprising of a double row of tracks (Hecht 2009). The markings are footprints that were preserved in sand and, through the sedimentation process, eventually became sandstone (Hagadorn and Belt 2008). Ichnofossils of Protichnites are particularly interesting in that the fossils could have been made by one of the first terrestrial animals on Earth (MacNaughton and Hagadorn 2006). This documented the important transition animals made from ocean to land that occurred during the Cambrian period (Hecht 2009). Evidence of odd markings that appear at regular intervals in some fossils suggests that these arthropods carried shells with them, possibly as a buffer against the terrestrial environment (Hecht 2009). The shells would help retain moisture and avoid excessive ultraviolet light (Hecht 2009). The behavior is similar to that of hermit crabs, butthe prints suggest that Protichnites share a closer resemblance to scorpions (Hecht 2009).

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Protichnites ichnofossil. Photo Credit: J. W. Hagadorn, Amherst College

Hagadorn J, Belt ES.2008. Stranded in upstate New York: Cambrian Scyphomedusae from the Potsdam sandstone. Palaios. 23: 424-441.

Hecht J. 2009. Early land visitors borrowed shells for protection. New Sci. 2703.

MacNaughton RB, Hagadorn J. 2006. Paleontological Report. Commission Geologique du Canada. Accessed 1 February 2010.