Ammonoid
Arnioceras
Sinemurian ammonite
Arnioceras is the small, sharply ribbed, keeled Sinemurian ammonite found in clusters on Lyme Regis and Charmouth limestone, often as blocks packed with dozens of individuals. Multi-ammonite Arnioceras blocks are beach finds under the Jurassic Coast code and modest in price. It is easily confused with juvenile Asteroceras and Promicroceras.
| Phylum | Mollusca |
|---|---|
| Class | Cephalopoda |
| Order | Ammonitida |
| Family | Arietitidae |
| Group | Ammonoid |
| Rank (PBDB) | genus· Paleobiology Database |
| Author | Hyatt 1867· Paleobiology Database |
| Classification (PBDB) | Mollusca › Cephalopoda › Ammonitida › Arietitidae· Paleobiology Database |
| Range (PBDB) | 201–175 Ma· Paleobiology Database |
| PBDB occurrences | 368· Paleobiology Database |
Photographs
Elsewhere
- GBIF: 4626472
- PBDB: 14579
- Wikidata: Q4794840
- PBDB taxon page
- Wikipedia: Arnioceras
- PBDB search: Arnioceras
Cite this article
Stratum Strata. "Arnioceras" (Taxon). Stratum Strata pack 2026.09, as of 2026-09-21. https://stratum.black/strata/taxa/arnioceras. Accessed 2026-09-21.
@misc{stratum-arnioceras,
title = {Arnioceras},
author = {{Stratum Strata}},
howpublished = {\url{https://stratum.black/strata/taxa/arnioceras}},
year = {2026},
note = {Taxon article, Stratum Strata pack 2026.09, as of 2026-09-21; sources: stratum, pbdb, wikidata, commons, nhm. Accessed 2026-09-21.}
} 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.