Bivalve
Exogyra
Cretaceous oyster
Exogyra is the coiled, thick-shelled Cretaceous oyster with a spiral umbo; E. costata and E. ponderosa are the large ribbed species of the Gulf and Atlantic coastal plains and Texas. They are abundant, legal on most private land and inexpensive, and often serve as the first fossil a southern collector finds. Whole two-valved specimens are less common than single lower valves.
| Phylum | Mollusca |
|---|---|
| Class | Bivalvia |
| Order | Ostreida |
| Family | Gryphaeidae |
| Group | Bivalve |
| Rank (PBDB) | genus· Paleobiology Database |
| Author | (Say 1820)· Paleobiology Database |
| Classification (PBDB) | Mollusca › Bivalvia › Ostreida › Gryphaeidae· Paleobiology Database |
| Range (PBDB) | 201–7.25 Ma· Paleobiology Database |
| PBDB occurrences | 1049· Paleobiology Database |
Elsewhere
- GBIF: 4595492
- PBDB: 16655
- Wikidata: Q127941
- PBDB taxon page
- Wikipedia: Exogyra
- PBDB search: Exogyra
Cite this article
Stratum Study. "Exogyra" (Taxon). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/taxa/exogyra. Accessed 2026-09-20.
@misc{stratum-exogyra,
title = {Exogyra},
author = {{Stratum Study}},
howpublished = {\url{https://stratum.black/study/taxa/exogyra}},
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.