New Study Pinpoints Emergence Of First Animals

Tribrachidium heraldicum, one of the most enigmatic critters from the Ediacara-fauna.
The Ediacaran, a geological period spanning from 635 to 538 million years ago, saw the emergence of the first complex multicellular animals after Earth was ruled for almost 3 billion years by microorganisms.
First described from the Ediacara Hills in Australia, Ediacara-type fossils have been found in Newfoundland, England’s Charnwood Forest, Namibia, Russia and China.
The Ediacara fossils includes many weird organisms of unknown affinity, like Dickinsonia, an egg-shaped, segmented hybrid between a worm and a jellyfish, Charnia, a segmented and branched organism resembling superficially modern sea pens, or Tribrachidium, showing a threefold rotational symmetry not found in any modern creature.
The beginning of the Ediacaran is marked by the Marinoan glaciation, a worldwide glaciation lasting from 654 to 632 million years ago. Its possible role in the emergence of the Ediacaran fauna has long been debated, with some researchers suggesting that the melting ice released nutrients into the sea, providing a fertile ground for complex life to evolve.
In a new study, Chinese researchers used cyclostratigraphy to exactly date the aftermath of the Marinoan glaciation and the emergence of the Ediacara fauna, suggesting that oxygen pulses played a mayor role.