Eldredgeops vs. Phacops

My fledging knowledge of fossils grew this month when University of Rochester Fossil Technician Gerry Kloc introduced me to Eldredgeops and his book on Trilobites of New York.

For over 150 years the common Devonian trilobite of New York and other North American locations had been referred to as Phacops rana, after the description and identification of Phacops latifrons  in Europe.  The literature, museums, and individual collections carry the name.  As it turns out, this North American trilobite is not a Phacops genus, but rather an Eldredgeops. Although this has been known in the paleontology world for two decades, many specimens continue to be misnamed.

A most thorough and readable note on the distinction between the two genus can be found on the Fossil Forum website (www.fossilforum.com).  The discussion, dated June 8, 2014, is called Phacops Vs Eldredgeops and is found in the General Discussion Forum of the website.  The author is Gerry Kloc, a Rochester paleontologist who has studied trilobites extensively.  Gerry has identified numerous subtle, but definitive, differences in the cephalons between the European Phacops rana and the so called North American variety.  He concludes that the Middle Devonian New York species is actually an Eldredgeops and proposes it be given the full name Eldredgeops rana.  If you have one, it is time to update your label.