Britannica Sources used in this answer

How did planktonic foraminiferans help correlate Late Cretaceous rocks in North America and the Caribbean?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Cretaceous paleogeography — Cretaceous Period Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the late Cretaceous Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.

Planktonic foraminiferans are essential for correlating Late Cretaceous strata because of their planktonic (drifting) life habit, which allows them to be distributed across wide geographic areas.1

In North America, these organisms have been used to correlate rock layers across regions including Texas, Arkansas, Mexico, and the Caribbean. Because they are free-drifting, they are not restricted by the same environmental barriers that limit bottom-dwelling or localized species, making them highly effective for regional biostratigraphic correlation. Furthermore, their contribution to fine-grained calcareous sediments during the Late Cretaceous provides a consistent fossil record that micropaleontologists use to establish high-resolution zones, facilitating the integration of these rocks into a broader geochronologic framework.123