Stratum.black
Trionyx — Trionyx
Trionyx — Wanax01, Wikimedia Commons, CC BY SA 4.0

Reptile

Trionyx

Soft-shelled turtle

Trionyx is the historic name for soft-shelled turtle shell fragments in Cretaceous and Paleogene river deposits; the pitted, vermiculate sculpture of trionychid shell is unmistakable and very common in Hell Creek and Judith River microsites. Modern workers assign most Cretaceous material to other trionychid genera, so 'Trionychidae indet.' is the safer label. Shell fragments are among the cheapest dinosaur-bed fossils.

PhylumChordata
ClassReptilia
OrderTestudines
FamilyTrionychidae
GroupReptile
Rank (PBDB)genus· Paleobiology Database
AuthorGeoffroy Saint-Hilaire 1809· Paleobiology Database
Classification (PBDB)Chordata › Reptilia › Testudines › Trionychidae· Paleobiology Database
Range (PBDB)126–0 Ma· Paleobiology Database
PBDB occurrences421· Paleobiology Database

Photographs

Trionyx — Trionyx, NON-TYPE (NHMUK PV R 5805)
Trionyx, NON-TYPE (NHMUK PV R 5805) — © The Trustees of the Natural History Museum, London, Natural History Museum (London) Data Portal, CC BY 4.0
Trionyx — Trionyx (NHMUK PV OR 33198)
Trionyx (NHMUK PV OR 33198) — © The Trustees of the Natural History Museum, London, Natural History Museum (London) Data Portal, CC BY 4.0

Age

Formations

Elsewhere

Cite this article

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

BibTeX · CSL-JSON

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

Citations carry the pack version and the article's as-of date so they resolve to the same text later. The facts themselves belong to the sources listed below; cite those for the science.