How are crocodiles related to dinosaurs? Why do they look alike?

Question

How are crocodiles related to dinosaurs? Why do they look alike?

Answer 1

"Archosaurs (by definition) include birds and crocodiles and all descendants of their closest common ancestor." See this picture for the cladistic branching:

http://www.indiana.edu/~ensiweb/images/d...

Simplified, it is like this:

There was an ancestor of all lizards (=lizards, snakes and tuataras), dinosaurs, crocodiles and birds. This ancestor diverged in lizards and the mentioned Archosauria.

Archosauria diverged into crocodiles and dinosaurs, which means that crocodiles are a sister group to dinosaurs (and so they "look alike"). But dinosaurs are direct ancestors of birds.