Quick: tell me what happened 1800-800 Mya! The quick answer to that is eukaryotes 1700 Mya. Recently mooted are chloroplasts 1342 Mya. Otherwise nothing. After 800 Mya we start seeing the Cryogenian phosphour chain and then the Ediacaran/Vendian, when the dynamo re-booted. Not as WOW DUDE as the Cambrian and points on, but of interest. Not so much before then.
This Boring Billion is, to palaeontologists (happy birthday Charles Darwin, by the way), the Annoying Billion because there was eukaryotic life on Earth throughout. But it did little except, literally, fester. Why weren't here a 1500 Mya chloroplast and a 1300 Mya trilobite?
Ming Tang, Xu Chu, Jihua Hao, and Bing Shen have a piece out on that: "Orogenic quiescence in Earth’s middle age" doi 10.1126/science.abf1876. Tang's quartet say that we were Heinlein's Sanctuary planet. They find that the crust thinned out starting 2500 Mya.
The continents ground into the Nuna-Rodinia pangaea, and stopped. (I take it that the crust was thinner elsewhere than here.) Its sinking mountains became hills. Flat, rounded, boring hills do not send phosphorous silt down slow, boring rivers. No change on land meant no evolution in the unchanging shoals.
Our crust thickened again 800 Mya on. And once life started getting bilateral-symmetric the dynamo rebooted.
ANNIVERSARY 2/12/22: Daily Mail, citing Ziyi Zhu. It finetunes the above: eukaryotes 1650 Mya, which then live a Zothique existence of quiet hopeless cannibalism.
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