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Hildoceras bifrons — Hildoceras bifrons
Hildoceras bifrons — Hildoceras_bifrons_Bruguière.jpg : Notafly derivative work: Cwmhiraeth, Wikimedia Commons, CC BY SA 3.0

Ammonoid

Hildoceras bifrons

Whitby ammonite

Hildoceras bifrons is the Toarcian ammonite named after St Hilda of Whitby, whose ammonites were said to be snakes she beheaded; it has a keel and a spiral groove along each flank. It is the signature ammonite of the Yorkshire coast and also occurs at Holzmaden. Whitby specimens are collected from foreshore nodules under the Yorkshire coast code.

PhylumMollusca
ClassCephalopoda
OrderAmmonitida
FamilyHildoceratidae
GroupAmmonoid
Rank (PBDB)genus· Paleobiology Database
Classification (PBDB)Mollusca › Cephalopoda › Ammonitida › Hildoceratidae· Paleobiology Database
Range (PBDB)193–175 Ma· Paleobiology Database
PBDB occurrences577· Paleobiology Database

Age

Formations

Elsewhere

Cite this article

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

BibTeX · CSL-JSON

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