Skip to main content
Timing of Latest Eocene Molluscan Extinction Patterns in Mississippi
  • David M. Hassl
  • Thor A. Hansen, Western Washington University
Document Type
Publication Date

Molluscs removed from 12 bulk samples of the Yazoo Formation (upper Eocene), exposed in a quarry at Cynthia, Mississippi, are similar in com- position and diversity to those found in the underlying upper Eocene Moodys Branch Formation, when dif- ferences in outcrop area are considered (74% of the Yazoo species are also found in the Moodys Branch). This suggests there was no significant extinction during the late Eocene (at the P15/P16 biozone boundary) as has been reported for planktic foraminifera. Only 11.4% of the species from the Yazoo extend into the Oligocene Red Bluff Formation, suggesting a large molluscan extinction at or near the Eocene-Oligocene boundary. The presence in the lowermost Red Bluff of an assemblage with a relatively high diversity dominated by suspension-feeding bivalves suggests that the molluscan fauna had recovered from the extinction by the earliest Oli- gocene.

Citation Information
David M. Hassl and Thor A. Hansen. "Timing of Latest Eocene Molluscan Extinction Patterns in Mississippi" Palaios Vol. 11 Iss. 5 (1996) p. 487 - 494
Available at: