The Fruitiness of August. The Silurian. Movement onto land

During the Silurian Period, the climate was generally warm and stable, in contrast to the glaciers of the late Ordovician and the extreme heat of the Devonian. A warm, stable climate provided for one of the most significant developments to take place during the Silurian Period: the arrival of the first plants to colonize the land. Lichens were probably the first photosynthetic organisms to cling to the rocky coasts of the early continents. When organic matter from decaying lichens joined the action of erosion to wear away rock, the first real soil began to build up in shallow, protected estuaries. Bryophytes such moss, hornworts and liverworts first appeared in the late Ordovician. The first known plant to have an upright stalk, and vascular tissue for water transport, was the Cooksonia of the mid-Silurian deltas. This little plant was a few centimeters high with a branched structure with small bulbous tips. It lacked true leaves, suggesting that the stalk developed to disperse spores and was not itself photosynthetic. The first known air-breathing animals were arthropods. Millipedes, centipedes and the earliest arachnids first appear in the Silurian. Since arachnids are exclusively predatory, this represents the first terrestrial food web.