Cambrian

The Cambrian ( ) is the first geological period of the Paleozoic Era and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 486.85 Ma.

thumb|Pannotia was centred on the South Pole, hence its name. Pannotia (from Greek: pan-, "all", -nótos, "south"; meaning "all southern land"), also known as the Vendian supercontinent, Greater Gondwana, and the Pan-African supercontinent, was a relatively short-lived Neoproterozoic supercontinent that formed at the end of the Precambrian during the Pan-African orogeny (650–500 Ma), during the Cryogenian period, and broke apart 560 Ma with the opening of the Iapetus Ocean, in the late Ediacaran and early Cambrian. Pannotia formed when Laurentia was located adjacent to the two major South Ameri

Cambria is a name for Wales, being the Latinised form of the Welsh name for the country, . The term was not in use during the Roman period (when Wales had not come into existence as a distinct entity) or the early medieval period. After the Anglo-Saxon settlement of much of Britain, a territorial distinction developed between the new Anglo-Saxon kingdoms (which would become England and Southern Scotland) and the remaining Celtic British kingdoms (which would become Wales and, before their absorption into England and Scotland, Cornwall to the south and Strathclyde or Hen Ogledd to the north). L

diversification of animal burrowing

level of oxygen (about 0.3% by volume) above which facultative aerobic microorganisms and facultative anaerobes adapt from fermentation to aerobic respiration