Conceptual illustration of the Middle Devonian, 393.3 and 382.7 million years ago, depicting an early Paleozoic forest. The first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. Plants include the Prefern, Cooksonia, lycopsid, lycophytes, Rhynia, Asteroxylon, Bryophytes, Zostera, fucoid algae, protolepidodendropsis, Rhacophyton.