I just read about the new caladonia crows that bend hooks on wire to retrieve food, and that have used 3 tools in sequence to grab food. So perhaps, dinosaurs with similar brain structure were smart too. Mammals evolved first and got outcompeted pretty badly for a very long time. Also, the sauropod body plan, long neck,sturdy legs, long tail, etc. With convergent evolution, how come it did not repeat in mammals? After all, in time terms, it was the most successful body plan ever for herbivores.
Humans do not seem to have been successful with the huge primate brain until very late in the day. Perhaps only
60,000 years ago, the geneticists say there were very few of us. We were fairly close to extinction. Then suddenly the penny dropped in some way and we exploded into action, spread round the world and quickly wiped out all the other advanced primates. Perhaps just one mutation in the brain of one guy or girl made the difference.
Now, if average world temp was raised 5 degrees and the O2 and CO2 levels were altered a lot, how would we compete? 35% Oxygen? Can humans survive in that?
1700 ppm CO2 might also be difficult. Will our smarts make the difference if the climate is toxic to our body plan?