Elrathia is a genus of trilobite belonging to Ptychopariacea known from the mid-Cambrian of Laurentia (North America).[2]E. kingii is one of the most common trilobite fossils in the USA[3] locally found in extremely high concentrations within the Wheeler Formation in the U.S. state of Utah.[4]E. kingii has been considered the most recognizable trilobite.[5] Commercial quarries extract E. kingii in prolific numbers,[4] with just one commercial collector estimating 1.5 million specimens extracted in a 20-year career.[6] 1950 specimens of Elrathia are known from the Greater Phyllopod bed, where they comprise 3.7% of the community.[7]
"...trilobite occupied the exaerobic zone, at the boundary of anoxic and dysoxic bottom waters. E. kingii consistently occur in settings below the oxygen levels required by other contemporaneous epifaunal and infaunalbenthic biota and may have derived energy from a food web that existed independently of phototrophic primary productivity. Although other fossil organisms are known to have preferred such environments, E. kingii is the earliest-known inhabitant of them, extending the documented range of the exaerobic ecological strategy into the Cambrian Period."
^Johnson, Kirk; Troll, Ray (2007). Cruising the fossil freeway: An epoch tale of a scientist and an artist on the ultimate 5,000-Mile paleo road trip. Golden, CO: Fulcrum Publishing. ISBN978-1-55591-451-6.
^Brett, C. E.; Allison, P. A.; Desantis, M. K.; Liddell, W. D.; Kramer, A. (2009). "Sequence stratigraphy, cyclic facies, and lagerstätten in the Middle Cambrian Wheeler and Marjum Formations, Great Basin, Utah". Palaeogeography, Palaeoclimatology, Palaeoecology. 277 (1–2): 9–33. Bibcode:2009PPP...277....9B. doi:10.1016/j.palaeo.2009.02.010.
^Gunther, L.F.; Gunther, V.G. (1981). "Some Middle Cambrian Fossils of Utah". Brigham Young University Geology Studies. 28: 1–81.