Australia: The Land Where Time Began

A biography of the Australian continent 

Cambrian Explosion - Lophotrochozoans: Spiralia

The lophotrochozoans phyla that have classic spiral cleavage in quartets appear to be well established as a monophyletic group, the Spiralia, and a complexity that varies from relatively simple flatworms to derived groups of annelids and molluscs, though they do not achieve the level of morphological complexity that is displayed by some ecdysozoans and deuterostomes.

Sources & Further reading

1. Erwin, Douglas H., & Valentine, James W., 2013, The Cambrian Explosion: The Construction of Animal Biodiversity, Roberts & Co., Greenwood Village, Colorado