Scientists often must try to measure things that they don’t have any real access to. Solar physicists try to image inside the sun by looking at magnetic waves rippling across the solar surface, for instance.
For those of us waiting for the day when we must build a jurassic park it is important to know a little dinosaur psychology. Luckily, some people are already on it, attempting to perform brain scans on the fossilized remains of these unlucky beasts. Their basic technique, I think, is to examine the shape of the bone where these anatomical features would exist in modern creatures. They use “micro-tomography” which I suppose means they can see very, very small indentations which seems a little suspicious, but hey, it’s science, they’d never lead us astray.
What do we now know? Well, Lambeosaurs don’t have a great sense of smell but they might socialize a fair bit. T. Rexes had small brains but relatively large olfactory bulbs, so their smell was better than average. They also had large inner-ear complexes, so they could either hear well or had really good balance, it’s not that important which, is it? Also, the Archaeopteryx, that dinosaur that can fly? It could also hear and vocalize well, like birds. And now you know.