How can the skeleton of mammals compared with the skeleton of birds and fish?

Question: How can the skeleton of mammals compared with the skeleton of birds and fish?
- Keywords:
  bird,
  fish,
  mammal,
  skeleton
Asked by BOB to Reka on 18 Nov 2016.
- Reka Nagy answered on 18 Nov 2016:
  
  As we all evolved from a common ancestor, we started off with the same set of bones that gradually became specialized or even lost as new species had no more use for them. So even though the bones of some animals look quite different to ours, we can figure out which bones in our body their bones correspond to!

Question: How can the skeleton of mammals compared with the skeleton of birds and fish?