linkedin post 2019-01-20 06:28:41

THE DOGMA. “The conventional interpretation of the metazoan body fossil record is that it documents an abrupt (in geological terms) appearance of animals around the base of the Cambrian Period 541 million years ago (Ma) – the “Cambrian Explosion” hypothesis. By around 520 Ma, virtually all of the animal phyla with recalcitrant tissues that one might expect to become fossilized are represented in the fossil record, as revealed by Lagerstätten such as the exceptionally preserved Chengjiang biota 4 (Fig. 1 summarizes major Ediacaran and early Cambrian fossil assemblages). However, this body fossil record is at odds with molecular clock analyses, which consistently indicate that Metazoa originated somewhere between 850 and 650 Ma in the Tonian or Cryogenian intervals, before diversifying through the Cryogenian and the Ediacaran.”

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