According to J.D.A. Piper, Rodinia is one of two models for the configuration and history of the continental crust in the latter part of Precambrian times. The other is Paleopangea, Piper's own concept. Piper proposes an alternative hypothesis for this era and the previous ones. This idea rejects that Rodinia ever existed as a transient supercontinent subject to progressive break-up in the latter part of Proterozoic times and instead that this time and earlier times were dominated by a single, persistent "Paleopangaea" supercontinent. As evidence, he suggests an observation that the palaeomagnetic poles from the continental crust assigned to this time conform to a single path between 825 and 633 million years ago and latterly to a near-static position between 750 and 633 million years. This latter solution predicts that break-up was confined to the Ediacaran period and produced the dramatic environmental changes that characterised the transition between Precambrian and Phanerozoic times.