If animal-complexity CNS is your criteria, then humans + octopuses would be a counterexample, as urbilaterals wouldn’t be expected to have such a system, and the octopus intelligence has formed separately.
The last common ancestor of humans and octopuses probably didn’t have a very complicated nervous system, but it probably did have a nervous system: most likely a simple lateral cord with ganglia, like some modern wormlike animals. That seems to meet the criteria for shminux’s “dedicated organism-wide communication subsystem”.
If animal-complexity CNS is your criteria, then humans + octopuses would be a counterexample, as urbilaterals wouldn’t be expected to have such a system, and the octopus intelligence has formed separately.
The last common ancestor of humans and octopuses probably didn’t have a very complicated nervous system, but it probably did have a nervous system: most likely a simple lateral cord with ganglia, like some modern wormlike animals. That seems to meet the criteria for shminux’s “dedicated organism-wide communication subsystem”.