Millions of years ago, humans and orangutans were the same species. Later, humans came from the forest to the grasslands, and gradually parted ways with their former brothers. It was also at this time that humans began to evolve into highly intelligent animals, and one of the most important changes was that humans stood up and began to walk on their feet.
The freed hands can do a lot of work, such as using tools, and then develop the brain, which has become what it is today. In fact, the orangutans in the forest are also developing in this direction, and many observers have found that orangutans can use wooden sticks as weapons, although they are advancing but much slower than people!
In fact, 70 million years ago, there was also a species of dinosaurs that had freed their hands, and this dinosaur was spinosaurus.
Although many of the dinosaurs walked on their feet, these dinosaurs did not have many functions for their forelimbs like spinosaurus. In the case of the Tyrannosaurus rex, its forelimbs are difficult to assist too much when hunting, because its forelimbs are too short. The forelimbs of the Tyrannosaurus rex are more used to balance the body.
This is not the case with Spinosaurus, whose forelimbs are far more useful than those of Tyrannosaurus rex. For example, spinosaurs have more developed forelimbs, and can still walk on all fours when their feet are tired.
Spinosaurus likes to eat fish in the river, and its forelimbs can help them catch fish in the river, just like humans in the water.
When eating, the forelimbs can also help dismember prey. When swimming, the forelimbs can also assist in swimming, increasing speed.
It can be said that the forelimbs of spinosaurs are more like primates than other dinosaurs, and the complex operation of the forelimbs has exercised their brains, so I think if there is a dinosaur that can evolve into a highly intelligent animal, spinosaurus is the most likely!