system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can anyone estimate dinosaur intelligence?

Like I get the basic physiological things that we can figure out, but how did Dr Grant know the Velociraptors were so smart and hunted in packs?

Is it just that they were medium sized predators? The pincer formation seems oddly specific in that case.
gpt
They do a cat-scan of the skull and can find the size/shape of the brain based on that. Then they compare the size/shape of the brain to other animals (example: the T-Rex's brain shape was really similar to an alligator) or the creature's brain-to-body ratio. The size of a brain doesn't determine intelligence. What matters is how big the brain is compared to the body of that animal. Human shave a brain six times the size that it should be for their bodies, thus we're really smart.

Because of this, we know that raptors were actually pretty intelligent. Not geniuses like they're portrayed in Jurassic Park but still clever and with incredible eye sight to help. We also know they hunted in packs due to their size being a weakness back then, how they designed (heavy, fast damage) and the number of different bite marks we find on herbivore bones. 

We also know that ecosystems have similar animals regardless of time period and animals today have filled the roll of animals from the ice age, which filled the rolls of animals from the dinosaur-days. A T-Rex is basically doing the same thing for the ecosystem that a bear does, as do raptors fill the same roll as wolves.