Browsing the "Cambrian" Category

The Cambrian period is a division of earth’s history spanning from around 541 to 485 million years ago, and during which animal ecosystems rapidly appeared in an event known as the ‘Cambrian explosion’. Cambrian faunas were dominated by arthropods such as trilobites, but also included sponges, molluscs, brachiopods, jellyfish and chordates (the group to which vertebrates belong). The Cambrian atmosphere had 16 times greater CO2 content and 37% less oxygen than the present. It was a warm period with temperatures on average around 7°C above present levels. The continents were all positioned in the southern hemisphere but were drifting steadily north. During the Cambrian, land was barren and lifeless.