Conceptual illustration of what the Devonian fossil forest at the Riverside Quarry site in Gilboa, New York, USA, may have looked like in the Middle Devonian period, approximately 390 million years ago. There are three major woody plant components of the forest preserved a the Gilboa site, Eospermatopteris or Cladoxylopsids, Tetraxylopteris and Lycopsids. 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.