Must everything in our society be based upon fantasy?
Of course they were not real dinosaurs. However, they were the most realistic rendering possible using available skeletons and knowledge of how muscles attach to bones, and possible colorings based on current evolutionary observations. Same kind of detailing used to do a facial reconstruction from the skull of an unknown murder victim to try to find the victims family or someone who might recognize the person. Definitely not a cartoon but an attempt at an accurate rendering based on scientific understandings.