Precambrian Age

Blurb

The Precambrian is the oldest era of Earth's history, and covers the period from its origins (4 billion and 500 million years ago), until the appearance of the invertebrates with exoskeletons (542 million years ago). In this long period of time, the planet, newly formed, was affected by cosmic events and geological shocking that border on the limits of imagination. At the beginning was given the name of azoic, meaning "lifeless" because it was believed that the environmental conditions, reconstructed on the basis of geological evidence, were such as not to allow any form of life, when in fact under the layers of rock dating to the Cambrian period were identified traces of life primordial, was renamed Archeozoic ("the remote life") or Precambrian. The rare fossil belong to species of plants and animals lived in the seas: algae, protozoa, coelenterates, mollusks, echinoderms, arthropods. The Precambrian is divided into three periods: Hadean, Archean and Algonquian.