Skeleton Proposals

How do they know that dinosaurs are reptiles? How come they are not mammals like horses and elephants? How do they know from skeletons we evolve? Are they even sure the skeleton remains are not Dr. Zeus or Cesar from Planet of The Apes instead of evolved man. What people think evolution when people look at apes? Apes have never talked or built houses, but birds and other animals build nests. How are they sure the skeletons are evolved and not cross bred?