Pannotia: To be or not to be?

Following a decade during which its presence was widely accepted, the existence of the putative Ediacaran supercontinent Pannotia has come into question since the turn of the millenium, largely due to the geochronology of Ediacaran-Cambrian orogens, which suggests that the supposed landmass had begun to break up well before it was fully assembled. Paleomagnetic data from this time interval have been used to both support and refute the existence of Pannotia, but are notoriously equivocal. Proxy signals for Ediacaran-Cambrian supercontinent assembly and breakup, although collectively compelling, can be individually challenged, and efforts to detect the mantle legacy expected of supercontinent amalgamation, while promising, are inconclusive. Yet the existence of Pannotia is central to the nature, duration and evolution of the supercontinent cycle, and dictates the cycle’s geodynamic pathway from the breakup of Rodinia to the assembly of Pangea. Hence, the question of Pannotia’s existence, like that of Hamlet, is one of fundamental importance and demands far more attention than it has hitherto received.