Stratum.black
Promicroceras — Promicroceras
Promicroceras — Ammojoe, Wikimedia Commons, CC BY SA 3.0

Ammonoid

Promicroceras

Charmouth ammonite

Promicroceras planicosta is the small, chunky-ribbed ammonite of the Charmouth Mudstone found pyritised or in limestone blocks with dozens together, the iconic Charmouth beach fossil. Pyritised examples are golden, cheap and prone to pyrite decay, so keep them dry. Limestone blocks with clustered Promicroceras and Arnioceras are sold prepared from the beach.

PhylumMollusca
ClassCephalopoda
OrderAmmonitida
FamilyEoderoceratidae
GroupAmmonoid
Rank (PBDB)genus· Paleobiology Database
AuthorSpath 1925· Paleobiology Database
Classification (PBDB)Mollusca › Cephalopoda › Ammonitida › Eoderoceratidae· Paleobiology Database
Range (PBDB)200–184 Ma· Paleobiology Database
PBDB occurrences15· Paleobiology Database

Photographs

Promicroceras — Promicroceras planicosta
Promicroceras planicosta — Smithsonian Institution (NMNHPALEO), Smithsonian Open Access, CC0
Promicroceras — Promicroceras pyritosum (NHMUK PI C 26875)
Promicroceras pyritosum (NHMUK PI C 26875) — © The Trustees of the Natural History Museum, London, Natural History Museum (London) Data Portal, CC BY 4.0
Promicroceras — Promicroceras Spath, 1925 (NHMUK PI C 2138)
Promicroceras Spath, 1925 (NHMUK PI C 2138) — © 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. "Promicroceras" (Taxon). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/taxa/promicroceras. Accessed 2026-09-20.

BibTeX · CSL-JSON

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