几十年来，科学家们认为，在5.42亿年前的寒武纪黎明之前，多细胞生命并不存在。 然后，在1967年，对寒武纪之前的岩床进行了仔细的地质研究，发现了被称为Charnia的边缘生物。 这是第一次发现确切的寒武纪之前的元古生物化石，并引起了轰动。 从那时起，已经发现了超过18个埃迪卡拉时期（寒武纪之前）的化石床，有超过100种不同类型的生物可以追溯到6亿年前。 科学家对这些古代形式是否与现代动物有关陷入深深的争论，而共识是其中一些是。

尽管常识告诉我们，现代门类起源于大约5.2亿年前的寒武纪大爆炸，但最近的发现证实了现代门类在埃迪卡拉纪的代表。 其中一些门类可能代表了与生物形式几乎没有关系的干系。 在埃迪卡拉纪有代表的门类是多孔类（海绵）、刺胞类（Inaria.）、栉水母类（comb jellies）、可能的软体类（Kimberella）、可能的Onychophora（ Xenusion）、可能的节肢类（Parvancorina）、可能的环虫类（Cloudina）、可能的棘皮类（ Arkarua）以及一个已灭绝的拟议双边动物的成员，Proarticulata（ Dickinsonia）。

Only three modern phyla (Porifera, Cnidaria, and Ctenophora) are mostly accepted by scientists as having existed in the Ediacaran period, and there is substantial reason to believe that Mollusca, Onychophora, Arthropoda, Annelida, and Echinodermata were represented as well. Early mollusks are among the oldest of the smally shelly fauna that mark the start of the Cambrian, and the Ediacaran fossil Kimberella has features like that of a mollusk, such as a univalve shell, and is found in conjunction with scrapings that strongly suggest a radula, the distinguishing feature of mollusks. Recent images of Xenusion strongly suggest that it is an early onychophoran (velvet worm), while Parvancorina clearly has a head, and despite the absence of fossilized limbs, looks like a stem group arthropod. Annelida and Echinodermata are more uncertain, but the numerous tube-shaped skeletons found from the Ediacaran period are suggestive of polychaete worms, and the five-fold symmetry of Arkarua makes it a probable echinoderm.