That gives plenty of time for some mechanism to evolve in one of the two branches and not in the other. RNA editing may not be rare in that part of the evolutionary tree but I do wonder if it was already present in that common ancestor.
I love those evolutionary trees. I recently read “The Rise and Reign of Mammals” [1] and it’s so interesting to find out that all mammals, and therefore humans, evolved from what was mostly a glorified ground squirrel (my words, not his).
My recollection of octopus eye development comes from "Other Minds" by Peter Godfrey-Smith, which you might like. Essentially the octopus brain like organs are another evolutionary convergence.
This week's EconTalk covers a theory of self consciousness coming about only after humans had words to describe it. I wonder if likewise the brain as a physical substrate for a mind can only come about from a set of sense organs like eyes.
Jaynes' idea was that if you went back and you looked at very early historical texts--particularly for him, the Iliad--the way that characters talk about their own minds and their own drives is extremely unusual, or you might say not at all modern. . . . But, what's actually going on, given what we know about the specialization between the hemispheres of the brain, is that essentially one side of the brain, one hemisphere of the brain is really communicating to the other. And, full human consciousness had not really been established at that time.
https://www.researchgate.net/figure/Phylogenetic-tree-depict...
That gives plenty of time for some mechanism to evolve in one of the two branches and not in the other. RNA editing may not be rare in that part of the evolutionary tree but I do wonder if it was already present in that common ancestor.