Silurian

is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago, to the beginning of the Devonian Period, 419.2 Mya. The Silurian is the shortest period of the Paleozoic Era.

plants
Increased volcanism, lack of soil and strong winds made the land not a very hospitable environment. Vascular plants, known from the late Ordovician, slowly began to inhabit more friendly environments. Thin grippers anchored the first of them in a thin layer of soil. the new plants formed is: Lycopodiaceae and Isoetaceae

animals
see this article→ silurian animals

and this is a list of the ordovician animals that survived to silurian:


 * trilobite
 * orthida
 * orthoceras
 * crinoid
 * belemnitida
 * agnatha

and this is a list of ordovician animals that did not survive to silurian or evolved into other animals


 * ostracoderm
 * wiwaxia
 * Cameroceras



Ordovician–Silurian extinction
Some scientists have suggested that the initial extinctions could have been caused by a gamma-ray burst originating from a hypernova in a nearby arm of the Milky Way galaxy, within 6,000 light-years of Earth. A ten-second burst would have stripped the Earth's atmosphere of half of its ozone almost immediately, exposing surface-dwelling organisms, including those responsible for planetary photosynthesis, to high levels of extreme ultraviolet radiation. Under this hypothesis, several groups of marine organisms with a planktonic lifestyle were more exposed to UV radiation than groups that lived on the seabed. This is consistent with observations that planktonic organisms suffered severely during the first extinction pulse.