Which fossils are most useful for correlating nonmarine Devonian deposits?

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

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

For the correlation of nonmarine Devonian deposits, the most useful fossils are freshwater fish and plant spores.12

While marine strata rely on groups such as conodonts and ammonites, continental deposits require different indicators. Freshwater fish, in particular, provide precise zonation; for instance, psammosteids (Agnatha) have been used to divide the Baltic Frasnian into at least five distinct time zones. Plant spores are also essential tools for geologists working to establish a chronology within these nonmarine environments.12