When did the first marshes and swamps appear in Earth’s history?

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Bald cypress trees with wide, flared trunks stand in still, shallow water in a Louisiana swamp, their green foliage creating a dense canopy. — Wetland Stately bald cypresses (*Taxodium distichum*) thriving in a Louisiana swamp.

The first marshes and swamps appeared during the Devonian Period, which occurred approximately 419.2 million to 358.9 million years ago.1

While these specific wetland types emerged in the Devonian, evidence of the earliest wetland plants dates back even further to the Ordovician Period (485.4 million to 443.8 million years ago), when the first terrestrial plants began colonizing land by relying on wet substrates. Following their initial appearance, swamps became particularly dominant across vast regions during the Carboniferous Period.1