Ammonoid
Harpoceras
Falciferum ammonite
Harpoceras falciferum is the keeled Toarcian ammonite with sickle-shaped ribs that names the falciferum zone of the Holzmaden shale and the Whitby Mulgrave Shale. Large flattened Harpoceras with a golden pyrite sheen are classic Holzmaden pieces, and Whitby examples come in nodules. It is frequently confused with Hildoceras, which has a groove along the flank.
| Phylum | Mollusca |
|---|---|
| Class | Cephalopoda |
| Order | Ammonitida |
| Family | Hildoceratidae |
| Group | Ammonoid |
| Rank (PBDB) | genus· Paleobiology Database |
| Classification (PBDB) | Mollusca › Cephalopoda › Ammonitida › Hildoceratidae· Paleobiology Database |
| Range (PBDB) | 201–143 Ma· Paleobiology Database |
| PBDB occurrences | 448· Paleobiology Database |
Elsewhere
- GBIF: 4626340
- PBDB: 14967
- Wikidata: Q3783467
- PBDB taxon page
- Wikipedia: Harpoceras
- PBDB search: Harpoceras
Cite this article
Stratum Study. "Harpoceras" (Taxon). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/taxa/harpoceras. Accessed 2026-09-20.
@misc{stratum-harpoceras,
title = {Harpoceras},
author = {{Stratum Study}},
howpublished = {\url{https://stratum.black/study/taxa/harpoceras}},
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.