Viewpoint: Yes, some species within the Ediacaran biota of the late Precambrian are the predecessors of modern animals.

Viewpoint: No, the late Precambrian life forms (Ediacaran biota) are not related to modern animals.

In 1946, Australian geologist Reginald Sprigg discovered fossilized remains of what turned out to be creatures from 544 to 650 million years ago. Their significance lay not merely in the fact that these were some of the oldest fossils ever discovered, but in their origins from what geologists call Precambrian times—long before the rise of most animal phyla found on Earth today. Scientists dubbed the creatures whose fossils Sprigg had discovered, which were apparently jellyfish-like forms in the shape of disks, Ediacara, after the Ediacara Hills where Sprigg had found them.

Other discoveries of Ediacara...