What happened during this time?
Movement of the early continents (Ur, Nena and Atlantica) moved towards each other
A supercontinent, called Columbia or Nuna, starts to forms (between 2.1 Ga - 1.8 Ga)
The activity of sulfur bacteria controlled, or influenced the formation of the Earth’s earliest phosphorites.
Two of the largest impact events occured during this time
Crater known as Sudbury Basin (Ontario, Canada)
250 km wide crater formed the end of the Orosirian (1.85 billion years ago).
The impactor was an asteroid at least 10 km in size
Prokaryotic cyanobacteria organisms continue to dominate
The Gunflint Chert from Minnesota and Ontario (Barghoorn & Tyler 1965) records evidence of increasing complexity in Precambrian life from ~1.88 bya
Evidence of stromatolites
Some of the earliest evidence of acritarchs found in the black chert layers
Appearance of Grypania spiralis which has a coiled, filamentous appearance that does not branch
Grypania has been observed at lengths over ½ meter (1½ feet) in length, but only 2 mm in diameter.
Specimens are found stretching from the Paleoproterozoic to the Neoproterozoic
The original dating is around 2.1 Ga (Grey and Williams 1990; Han and Runnegar 1992; Kumar 1995), although these older specimens are not well preserved and debated
Paleoproterozoic specimens of Grypania could also be giant bacterium or bacterial super colony, similar to Thiomargarita magnifica, a megabacterium found in the Caribbean mangroves that can reach up to 2 cm (Volland et al. 2022)
Some researchers think that younger specimens dating to Mesoproterozoic (~1,450 mya) are different from the Paleproterozoic specimens (Knoll et al. 2006).
These younger specimens are almost definitely eukaryotes possibly green, Chlorophyceae algae
Above: An early eukaryotic algae, Grypania