Not sure what's meant by "intelligence" or "twice" here, since the study in question (https://www.science.org/doi/10.1126/science.adv2609 https://www.science.or

Not sure what's meant by "intelligence" or "twice" here, since the study in question (https://www.science.org/doi/10.1126/science.adv2609 https://www.science.org/doi/10.1126/science.adv2609) concerns the pallium in both birds and mammals. So it seems something about the basal pallium in reptiles was suitable to give rise to bird pallia and the mammalian isocortex, under suitable evolutionary pressures.