Cambriiskauden

The Cambrian period, often referred to as the "Cambrian explosion," marks a pivotal era in Earth's history. It is the first period of the Paleozoic Era and began approximately 541 million years ago, lasting until about 485.4 million years ago. This period is characterized by the relatively sudden appearance of a vast array of complex, multicellular life forms. Prior to the Cambrian, life on Earth was predominantly microbial and simple, but the Cambrian saw the emergence of most major animal phyla that exist today.

Fossils from the Cambrian period reveal an astonishing diversity of organisms, including early arthropods, mollusks, and the first vertebrates. Trilobites, a group of extinct marine arthropods, are among the most iconic and abundant fossils from this time. The oceans teemed with new life, with creatures developing hard exoskeletons, shells, and complex body structures for the first time. This evolutionary burst is thought to have been driven by a combination of factors, including increasing oxygen levels in the atmosphere and oceans, the development of new genetic toolkit for building complex bodies, and predator-prey relationships that spurred evolutionary innovation.

The geological record of the Cambrian is primarily found in sedimentary rocks, particularly those formed in shallow marine environments. Major fossil sites, such as the Burgess Shale in Canada and the Chengjiang biota in China, provide invaluable insights into the flora and fauna of this transformative period. The Cambrian period laid the foundation for the subsequent evolution of life on Earth, shaping the biodiversity we see today.