Question: how do we know what colour dinosaurs were and what they ate.

Elaine Cloutman-Green answered on 23 Jun 2014:

We have some idea what certain dinosaurs had in terms of skin pattern and colouration from very rare sample of fossilized skin. In a lot of cases though we make a best guess based on what the modern day decedents of those dinosaurs look like.

Working out what dinosaurs ate in sometimes easier as we have their teeth (so can judge if they ate plants or animals) and know what animals were around in the same region at the same time. So in this case it’s sometimes easier to put the pieces of the puzzle together. That said we can’t guarantee if you got into a time machine that you would find exactly what we predicted.