Elrathia Explained

Elrathia is a genus of trilobite belonging to Ptychopariacea known from the mid-Cambrian of Laurentia (North America).^[1] E. kingii is one of the most common trilobite fossils in the USA^[2] locally found in extremely high concentrations within the Wheeler Formation in the U.S. state of Utah.^[3] E. kingii has been considered the most recognizable trilobite.^[4] Commercial quarries extract E. kingii in prolific numbers, with just one commercial collector estimating 1.5 million specimens extracted in a 20-year career.^[5] 1950 specimens of Elrathia are known from the Greater Phyllopod bed, where they comprise 3.7% of the community.^[6]

Etymology

Even though the generic name Elrathia was first published in the combination E. kingii, a species from the House Range, Utah, the name, itself, is derived from Elrath, Cherokee County, Alabama.^[7]

Description

E. kingii is a medium-sized trilobite with a smooth sub-ovate carapace that is tapered towards the rear. Thorax is usually 13 segments. Pygidium has four axial rings and a long terminal piece. Posterior margin of the pygidium has a long broad medial notch.

In contrast, E. marjumi usually has 12 segments, 5 axial rings, lacks a notched posterior margin and possess incipient antero-lateral spines.

The British Columbian species, E. permulta, is much smaller, averaging about only 20 millimeters, and has up to thoracic 14 segments. Because E. permulta lacks several diagnostic features of the genus it may even represent a distinct genus.

See also

• Hypoxia (environmental)
• Paleobiota of the Burgess Shale

External links

• Web site: 2011. Elrathia permulta. Burgess Shale Fossil Gallery. Virtual Museum of Canada. https://web.archive.org/web/20201112025257/http://burgess-shale.rom.on.ca/en/fossil-gallery/view-species.php?id=6. 2020-11-12. dead. 2023-01-21.
• Web site: 2011. Elrathina cordillerae. Burgess Shale Fossil Gallery. Virtual Museum of Canada. https://web.archive.org/web/20201112025257/http://burgess-shale.rom.on.ca/en/fossil-gallery/view-species.php?id=7. 2020-11-12. dead. 2023-01-21.
• Web site: Order Ptychopariida. A Guide to the Orders of Trilobites. Sam Gon III. 2009.

Notes and References

1. Geyer . Gerd . Peel . John S. . March 2017 . Middle Cambrian trilobites from the Ekspedition Bræ Formation of North Greenland, with a reappraisal of the genus Elrathina . Journal of Paleontology . en . 91 . 2 . 265–293 . 10.1017/jpa.2016.152 . 2017JPal...91..265G . 0022-3360. free .
2. Book: 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. Fulcrum Publishing. Golden, CO. 978-1-55591-451-6.
3. Robert R.. Gaines. Mary L.. Droser. 2003. Paleoecology of the familiar trilobite Elrathia kingii: An early exaerobic zone inhabitant. Geology. 31. 11. 941–4. 10.1130/G19926.1. 2003Geo....31..941G.
4. Allison. C. E.. P. A.. Desantis. Liddell. Kramer . M. K.. W. D.. A.. Sequence stratigraphy, cyclic facies, and lagerstätten in the Middle Cambrian Wheeler and Marjum Formations, Great Basin, Utah. Palaeogeography, Palaeoclimatology, Palaeoecology. 277. 9–33. 2009. Brett. 1–2. 10.1016/j.palaeo.2009.02.010 . 2009PPP...277....9B.
5. Gunther. L.F.. Gunther. V.G.. 1981. Some Middle Cambrian Fossils of Utah . Brigham Young University Geology Studies. 28. 1–81.
6. Caron . Jean-Bernard. Jackson . Donald A.. Taphonomy of the Greater Phyllopod Bed community, Burgess Shale. PALAIOS . 21 . 5 . 451–65. October 2006. 10.2110/palo.2003.P05-070R. 20173022. 2006Palai..21..451C . 53646959 .
7. Book: Resser, Charles Elmer. 1938. Cambrian System (Restricted) of the Southern Appalachians. Geological Society of America Special Paper. 15. 77. 081372015X.