Präkambrium

the Präkambrium (of lat. prae = forwards and Kambrium), is the time before the earth-history age of the Kambriums and thus a recapitulatory name for the earth-history Äonen Hadaikum, Archaikum and Proterozoikum. The Präkambrium covers a length of time of approximately 4 billion years,from the time of the emergence of the earth forwards approx. 4,55 billion years up to the beginning of the Kambriums forwards approx. 543 million years.

In the Präkambrium the first organisms, from which however only few fossils are received, developed e.g. Bacteria like the Cyanobakterien. The time period of theSometimes Präkambriums, from which admits fossils are, is called also Kryptozoikum and distinguished from the Archean rocks, in which there was probably still no life on earth.

Toward end of the Präkambriums also more-cellular organisms, those developed partially among the forerunners of still existing groups of organismsare counted like sponges (Porifera) and Nesseltiere (Cnidaria), partially in addition, heavily or not at all into those today admitted structural drawings groups of organisms, which can be arranged. Discovery sites of präkambrischer formations are rare on earth, and those old rocks were over-formed often several times by tectonic procedures. Name-givingfor the Ediacara fauna, a community of organisms of the late Präkambriums, is the Ediacara formation of Flinders rank in Australia, whose Entsprechnungen occurs also in Canada and Namibia. This last section of the Präkambriums becomes as Ediacarium or in former times also as Vendium (see. Vendobionten) designates.

The discovery sites of the fossils of the Ediacara fauna are on different today's continents. Much points however on the fact that at that time the land masses had merged supercontinent into one „“. Traces of präkambrischen Vergletscherungen in Namibia and Canada speak also for one or more world-wide ice ages in the Präkambrium (Snowball Earth). Only the transition to a warmer climate made the Kambri explosion, better to call Kambri radiation, the life on earth at the beginning of the Kambriums possible.

For the emergence of the life on earth there are so far only different acceptance,since such developing procedures were observed so far neither in nature, to be still experimentally represented could. Anyhow completely different chemical and climatic conditions than in prevailed the later Präkambrium in the early Präkambrium. One assumes that itself the life in the Ursuppe in such a way specified by chemical reactionsto have formed could, this theory is however disputed. Exist also theories, which represent the acceptance that the life is to have resulted from the impact of Asteroiden or comets and/or. individual amino acids or living cells with this extraterrestrial Gesteinsbrocken arrived on earth itsare (Panspermie).

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