lateProterozoic

Late Proterozoic refers to the latter portion of the Proterozoic Eon, traditionally equated with the Neoproterozoic Era, roughly 1,000 to 541 million years ago. This interval encompasses three formal subdivisions: the Tonian, Cryogenian, and Ediacaran periods. The late Proterozoic is characterized by major climatic, oceanographic, and biospheric changes that set the stage for the Phanerozoic.

The Cryogenian period within the late Proterozoic is notable for extensive glaciations, including the Sturtian and Marinoan events, which led to proposals of global or near-global ice cover often referred to as Snowball Earth scenarios. Following deglaciation, climate and oceanography remained dynamic, with fluctuations in temperature, ice cover, and redox conditions. Evidence also points to episodes of renewed oxygenation of deep oceans during this time, occurring in the broader context of rising atmospheric oxygen levels.

Biologically, the late Proterozoic witnessed important innovations. The Ediacaran fauna, a diverse assemblage of soft-bodied organisms, appears in the fossil record during the late Neoproterozoic. By the end of the Ediacaran, the first skeletal metazoans and more widespread animal-like life are represented by small shelly fossils and other early coral- and tubular-organism groups, signaling increasing complexity that culminates in the Cambrian explosion.

Tectonically, the era records the breakup of the supercontinent Rodinia and the formation of subsequent landmasses such as Pannotia, reshaping ocean basins and global circulation. The late Proterozoic thus marks a transitional interval with pivotal climatic shifts, radical changes in ocean chemistry, and the emergence of multicellular life, preceding the rapid diversification of life in the Phanerozoic.