Would Dinosaurs Got Smart?

[The Lake-]

I mean, pretty distantly related from any recognizable dinosaurs.

No, I am not saying the T-Rex had wings. That would be nightmarish

"not to scale"
inconsolable sadness of no colossal chicken wings

[Forsher]

No, I am not saying the T-Rex had wings. That would be nightmarish

"not to scale"
inconsolable sadness of no colossal chicken wings

https://en.wikipedia.org/wiki/Bullockornis

aka The Demon Duck of Doom, but it may be more closely related to chickens.

[Eahland]

A backpacking trip requires difficult carrying decisions, but they aren't nearly as difficult as the carrying decisions required when you move to another country. When our ancestors invented bags, they were able to simultaneously carry more things, which meant having to make even harder carrying decisions. The carrying decisions became even harder when they started using rafts and canoes to move resources. Same thing with beasts of burden and carts.

1. It is beneficial to be able to simultaneously allocate more resources
2. Deciding the optimal combination of resources requires brainpower
3. Larger possible combinations of resources requires more brainpower
4. Our ancestors varied in terms of brainpower
5. As a result of the pressure from increasingly more difficult carrying decisions, our ancestors with more brainpower exerted greater influence on the gene pool.

As a long-time nethack player, I can assure you that carrying decisions become easier and less consequential as your carrying capacity increases.

When you're trying to decide between, "Do I want to carry this food ration in case I don't find enough monsters I can eat, or this potion that I think is healing in case I find too many monsters that can eat me? Or maybe both and be Burdened? Or swap the chain mail for lighter but less protective armor so I can carry the food and potion without being Burdened?" those decisions are much more difficult and consequential to your continued survival than when you can just throw whatever you run across that looks useful into your blessed bag of holding, and your decisions are more on the order of, "Do I really need two dozen food rations in case I run out of monsters to eat, or would a dozen be enough?"

Also there's such a thing as permanent storage. Sapient creatures don't need to carry everything they own on their persons at all times.