I'm not sure why, but I'd been under the impression that things like the optic tectum and basal ganglia developed post-2R (the double duplication of the genome ~1/2 Ga).

Lampreys (as far as I'm aware), also have these brain structures. The problem is that TimeTree seems to indicate that - unless the outlier of Otsuka et al is correct - lampreys diverged before then:

estimations of human-lamprey divergence times

While trying to figure out which bit of my thinking is wrong, I came across this article that suggests lampreys had whole genome duplications, but completely separately to those in our lineage.

Does this mean that their structures evolved convergently? (Perhaps they're "obvious" things to evolve post-WGDs?) Or is my initial assumption wrong, and the structures are much older than 2R and pre-divergence from lampreys?

Or something else entirely? I'm confused, and I'm sure I'm missing something: I just don't know what.


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