Stratum.black
Elrathia kingii — Elrathia kingii
Elrathia kingii — Wilson44691, Wikimedia Commons, Public domain (US)

Trilobite

Elrathia kingii

Utah trilobite

Elrathia kingii from the Wheeler Shale is the most abundant and most widely sold trilobite in the world, a small ptychopariid with a wide thorax and small pygidium, dark grey-black on light grey shale. Millions have been quarried near Delta, Utah, and made into jewellery; a natural specimen costs a few dollars. It is nonetheless enhanced: scribed outlines, blackened shells and cast-resin replicas glued to real shale all circulate.

PhylumArthropoda
ClassTrilobita
OrderPtychopariida
FamilyAlokistocaridae
GroupTrilobite
Size1–4 cm
Rank (PBDB)species· Paleobiology Database
Author(Meek 1870)· Paleobiology Database
Accepted name (PBDB)Elrathia kingi· Paleobiology Database
Classification (PBDB)Arthropoda › Trilobita › Ptychopariida › Alokistocaridae· Paleobiology Database
Range (PBDB)506–497 Ma· Paleobiology Database
PBDB occurrences9· Paleobiology Database

Restoration and fakes

Genuine Elrathia have slightly convex shells with fine surface texture; painted or resin examples are flat, glossy and uniform. A blade under the edge of a resin 'trilobite' lifts it.

Age

Formations

Elsewhere

Cite this article

Stratum Study. "Elrathia kingii" (Taxon). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/taxa/elrathia-kingii. Accessed 2026-09-20.

BibTeX · CSL-JSON

@misc{stratum-elrathia-kingii,
  title        = {Elrathia kingii},
  author       = {{Stratum Study}},
  howpublished = {\url{https://stratum.black/study/taxa/elrathia-kingii}},
  year         = {2026},
  note         = {Taxon article, Stratum Study pack 2026.09, as of 2026-09-19; sources: stratum, pbdb, wikidata, commons. Accessed 2026-09-20.}
}

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