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Psiloceras — Psiloceras
Psiloceras — Cette image a été créée par Savant-fou Elle est donc sous licence libre . Si jamais vous avez besoin d'autres clichés su, Wikimedia Commons, CC BY SA 3.0

Ammonoid

Psiloceras

Hettangian ammonite

Psiloceras planorbis is the smooth, flat ammonite that marks the base of the Jurassic at the Blue Lias of Watchet and Lyme Regis, often preserved as crushed nacreous shells on limestone slabs. Slabs of iridescent Psiloceras from Somerset and Dorset are cheap and decorative. It is one of the few fossils that define a geological period boundary.

PhylumMollusca
ClassCephalopoda
OrderAmmonitida
FamilyPsiloceratidae
GroupAmmonoid
Rank (PBDB)genus· Paleobiology Database
Classification (PBDB)Mollusca › Cephalopoda › Ammonitida › Psiloceratidae· Paleobiology Database
Range (PBDB)206–175 Ma· Paleobiology Database
PBDB occurrences189· Paleobiology Database

Photographs

Psiloceras — Habenaria psiloceras Welw. ex Rchb.f., Type (NHMUK BM000032012)
Habenaria psiloceras Welw. ex Rchb.f., Type (NHMUK BM000032012) — © 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. "Psiloceras" (Taxon). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/taxa/psiloceras. Accessed 2026-09-20.

BibTeX · CSL-JSON

@misc{stratum-psiloceras,
  title        = {Psiloceras},
  author       = {{Stratum Study}},
  howpublished = {\url{https://stratum.black/study/taxa/psiloceras}},
  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.}
}

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