Question: how do we know about dinosaurs

Adrien Chauvet answered on 20 Nov 2020:

You look at fossils, compare them between each other, and to whatever is still alive today. Then you can try to classify them in group.
Depending on which strata (earth layer) you find them in, you can estimate their age.
The bigger the dinosaur, the less likely you will find a complete skeleton. Hence, there is also a lot of guess work around reconstituting full skeleton.
Based on the skeletal structure, you can infer about shapes, postures, diet, etc.
While these are all guesses, it is a whole science on its own, and it is quite amazing to see how much you can know about an animal just by looking at its bones.