Theoretical Importance
The Cambrian explosion is an apparently rapid increase in the variety of basic body structures of animals in the Early Cambrian period, starting after 543 million years ago and finishing before 518 million years ago. A few of the Early Cambrian fossils were already known in the mid-19th century, and Charles Darwin saw the apparently sudden appearance and diversification of animals as one of the main objections that could be made against his theory of evolution by natural selection.
The majority of animals more complex than jellyfish and other Cnidarians are split into two groups, the protostomes and deuterostomes. The mollusc-like features of Kimberella strongly suggest that it was a member of the protostomes. If so, this means that the protostome and deuterostome lineages must have split some time before Kimberella appeared — at least 558 million years ago, and hence well before the start of the Cambrian 541 million years ago. Even if it is not a protostome, it is widely accepted as a member of the more inclusive bilaterian clade. Since fossils of rather modern-looking Cnidarians have been found in the Doushantuo lagerstätte, the Cnidarian and bilaterian lineages would have diverged well over 580 million years ago.
Read more about this topic: Kimberella
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