The Mesoproterozoic Era is a geologic era within the Proterozoic Eon, being the second of three periods, and falls in between the Paleoproterozoic and the Neoproterozoic eras. It occurred between 1600-1000 million years ago (Ma). The Mesoproterozoic is the first period of Earth’s history with a respectable geological record. The continental masses of the Mesoproterozoic are more or less the same ones that are with us today. This is also the period when the formation of the Rodinia supercontinent occurred, as well as the breakup of the Nuna (Columbia) supercontinent.

The period is marked by further development of continental plates and plate tectonics. At the end of this era, the continental plates that had developed were more or less the same as what we have today. This period is also known for the first evidence of large-scale mountain building, namely with the Grenville Orogeny, for which extensive evidence still survives in the geologic record.

The Mesoproterozoic is also the most prolific time for Stromatolites, as they began to decline during the Neoproterozoic. Perhaps the greatest evidence recorded from the Mesoproterozoic period is the first known presence of sexual reproduction, which greatly increased the complexity of life to come. It was also the start of development of communal living among organisms, the multicellular organisms.

The Mesoproterozoic period can be broken down into three subdivisions, which are divisions based on time, rather than geological processes. These subdivisions, in order of oldest to youngest, are: the Calymmian (1600-1400 Ma), the Ectasian (1400-1200 Ma), and the Stenian (1200-1000 Ma).

Image Caption: The geological clock: a projection of Earth’s 4,5 Ga history on a clock (“MA” = a million years (Megayear) ago; “GA” = a billion years (Gigayear) ago). Credit: Woudloper/Wikipedia