That’s part of the process. As we find out more fossils and new evidence, we understand a bit better how these animals worked and looked like.
This is not the link I was looking for but it also shows some revisions we did throughout the years:
https://nixillustration.com/...
Dinosaurs were reconstructed based of modern reptiles, so dinosaurs have bony lizard faces because they are based on crocodiles and similar reptiles. If you want to reconstruct a mammal from the bones you surely have to consider the fact that modern mammals have different chubbier features
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