It’s pretty wild to think intelligence might have evolved more than once in vertebrates. The example of birds and mammals both developing complex brains is fascinating. It makes you wonder how much untapped potential animals might have in terms of intelligence that we haven’t fully understood yet.
While typically both mammals and birds are significantly more intelligent than the other vertebrates, it must be not forgotten that there exists an overlap in intelligence between the smartest reptiles, e.g. varans a.k.a. monitor lizards, and the dumber mammals and birds.
So also outside of mammals and birds there are some cases of brain evolution towards greater complexity, even if not reaching the typical mammal/bird level, and which are likely to also correspond to a somewhat different brain structure.
(Off topic, in my opinion, "reptiles", is a term that is properly applied only to lizards and snakes. Not only crocodiles and turtles are more closely related to birds than to lizards and snakes, but also none of them are crawling, as implied by the word "reptile". Actually the present crocodiles are awkward on land only because they are secondarily adapted to an aquatic life. Their terrestrial ancestors were much more agile, as still demonstrated by some crocodiles that are even now able to gallop.)
> Not only crocodiles and turtles are more closely related to birds than to lizards and snakes
Most fish (bony fish) are more closely related to us than they are to sharks and other cartilaginous fish. Technically we're all air breathing walking bony fish.
> It’s pretty wild to think intelligence might have evolved more than once in vertebrates
It's an utter bombshell if true. It means intelligence isn't "difficult" for evolution to arrive at, significantly increasing the odds of other intelligent life in the universe.
