Coeval

Coeval is an adjective meaning existing at the same time or of the same age. It is used to describe events, objects, or organisms that share the same chronological period. The term derives from Latin coevalis, formed from co- “together” and aevum “age.”

In geology and stratigraphy, coeval strata are rock sequences that formed during the same geologic interval, often separated by distance. Demonstrating coevality relies on fossil assemblages, radiometric dating within uncertainties, and cross-cutting or correlation with marker beds. The concept is relative rather than absolute, reflecting shared timing rather than identical origin.

In biology and paleontology, coeval organisms or populations are those that lived at the same time. Describing extant or extinct species as coeval helps researchers compare contemporaneous ecosystems and evolutionary contexts.

In archaeology, artifacts or cultural phases may be described as coeval when they originate in the same historical period, even if found in different regions. In many contexts, coeval is synonymous with contemporaneous, simultaneous, or synchronous, though usage can vary by discipline.