There was a reference to complex pre-Cambrian life in a book I’m reading, Kraken, and it made me double-check Wikipedia’s Cambrian explosion entry. Lacking total clarity, I decided to read a new paper which was published in Nature, Earth’s earliest non-marine eukaryotes. The Cambrian explosion is pegged to ~500 million years ago, but these data indicate a freshwater ecosystem which predates ~1 billion years before the present. Also, there was weird stuff in the discussion which startled me:
…Early eukaryotes were clearly capable of diversifying within non-marine habitats, not just in marine settings as has been generally assumed. This idea directly supports phylogenomic studies which find that the cyanobacteria evolved first in freshwater habitats and later migrated into marine settings….
Cyanobacteria are the ubiquitous blue-green algae which were’t familiar with. New Scientist has some quotes from paleontologists who seem to think that this paper is credible. There’s a good and a bad to this. The good, I’ll have to read up on this area which I’m so fuzzy about in terms of details. The bad is that it slices my finite time pie even more.