Silurian

The Silurian is a period of the Paleozoic era that lasted from approximately 443.8 million to 419.2 million years ago. It is named after the Silures, a Celtic tribe that inhabited the region of modern-day Wales during the Roman era. The Silurian period is divided into three epochs: the Llandovery, Wenlock, and Ludlow. It is characterized by the emergence of the first jawed fish, the ostracoderms, and the diversification of early tetrapods, which are the ancestors of modern amphibians and reptiles. The climate during the Silurian was generally warm and humid, with extensive tropical forests and shallow seas covering much of the Earth's surface. The Silurian period is notable for the deposition of significant amounts of black shale, which is rich in organic matter and has been a source of oil and gas in many parts of the world. The end of the Silurian period was marked by a major extinction event, known as the Lau event, which wiped out many marine species and paved the way for the subsequent Devonian period.