Ammonoid
Sphenodiscus
Wedge ammonite
Sphenodiscus is a sharp-keeled, discoidal Maastrichtian ammonite with a highly frilled suture, found in the Fox Hills Formation, the Gulf Coast Ripley and Coon Creek beds, and Texas. Its steinkerns display sutures spectacularly and are sold as 'suture ammonites'; shelled specimens with nacre are rarer. A complete Sphenodiscus can reach 30 cm.
| Phylum | Mollusca |
|---|---|
| Class | Cephalopoda |
| Order | Ammonitida |
| Family | Sphenodiscidae |
| Group | Ammonoid |
| Rank (PBDB) | genus· Paleobiology Database |
| Author | (Meek 1871)· Paleobiology Database |
| Classification (PBDB) | Mollusca › Cephalopoda › Ammonitida › Sphenodiscidae· Paleobiology Database |
| Range (PBDB) | 93.9–61.7 Ma· Paleobiology Database |
| PBDB occurrences | 242· Paleobiology Database |
Elsewhere
- GBIF: 4627379
- PBDB: 15655
- Wikidata: Q7576640
- PBDB taxon page
- Wikipedia: Sphenodiscus
- PBDB search: Sphenodiscus
Cite this article
Stratum Study. "Sphenodiscus" (Taxon). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/taxa/sphenodiscus. Accessed 2026-09-20.
@misc{stratum-sphenodiscus,
title = {Sphenodiscus},
author = {{Stratum Study}},
howpublished = {\url{https://stratum.black/study/taxa/sphenodiscus}},
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.