The 540 Ma (million years ago) Cambrian Explosion represents the greatest expansion in animal diversity on Earth. However, this event was preceded by a diverse suite of large complex multicellular organisms: the Ediacara biota. These enigmatic organisms comprised both animals and extinct lineages. Three hypotheses have been proposed to explain their disappearance: 1) An environmentally-driven Mass Extinction due to a rapid and global catastrophic environmental stress, 2) The Cheshire Cat model that proposes a change in the geological conditions responsible for the fossilization of the Ediacara biota and a disappearance that represents a failure of the fossil record rather than an extinction, and 3) a biologically mediated replacement that proposes a replacement of the Ediacara biota by animals due to the evolution of predation and complex food webs. The disappearance of the Ediacara biota marks the demise of the first diverse array of large, complex multicellular organisms. Fieldwork combining geological and paleontological investigation from around the world (Newfoundland, Namibia, Australia, and Iran) has allowed Marc Laflamme to evaluate the tempo and mode of the Ediacaran extinction, and give added context to the dramatic Cambrian radiation of complex animals.