30 dezembro 2010

The Ediacaran Period

The Ediacaran Period was a time when bizarre-shaped soft-bodied creatures dwelt on the sea floor, just prior to the explosion of skeletal life forms in the Cambrian Period. The Ediacaran is the last period of the Proterozoic Eon, dating from 650 Ma to 542 Ma, is named after the type-fossil locality at the Ediacara Hills in South Australia. 
Wilpena Pound (above) is a massive curved natural syncline in southern Australia.  

This period represents the ending of a global galciation, one that held almost entirely the Earth's surface (an effect known as the Snowball Earth), and marks the first worldwide appearence of somewhat complicated trace fossils.
At that time, all the continents were together in the supercontinent Pannotia. Before Pannotia, the former global supercontinent was Rodinia, broken about 800 Ma. Rodinia displacement led to the birth of the Ocean Pantalassa (or Paleo-Pacific) and eight continents who met again after to form the supercontinent Pannotia. 540 Ma ago, only after 60 Ma of its formation, Pannotia fragmented, originating the supercontinent Gondwana and three small continents, Laurentia, Siberia and Baltica. At the end of the Paleozoic the continents will met again one more time to form Pangea, the last supercontinent.
The supercontinent Pannotia (above), 550Ma ago.

The study of Ediacaran Period life records is relevant to the search for extraterrestrial life because conditions similar to Snowball Earth might exist elsewhere in the solar system. Beneath the icy crust of Jupiter´s moon Europa, an ocean has been suggested, perhaps making complex life feasible there.

Adpated from:
Geologica (Amazon.com link

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