Labels:bulletin board | reckoner OCR: the major theme of life's history even if they can be plausibly explained by lack of sufficient atmospheric oxygen for most of Precambrian time or by failure of unicellular life to achieve some structural threshold acting asa prerequisite to multicellularity More curiously. all major stages ir organizing animal life's multicellular architecture then occurred in a short period beginning less than 600 million years ago and ending by about 530 million years ago and the steps within this sequence are also discontinuous and episodic not gradually accumulative The first fauna called Ediacaran to honor the Australian locality of its initial discovery but now known from rocks on all continents, consists of highly flattened fronds sheets and circlets composed of numerous slender segments quilted to ...
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