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It's common knowledge that the saying "the strong survive" means that the best life form will stay alive will the weak with struggle or not survive. Through the 2 hundred years of people researching and finding dinosaur remains to them its common knowledge that 99% of dinosaurs had a very small brain. They can tell by the skull fossils and how much space is left for the brain inside as well as certain body features that many dinosaurs had. Most dinosaurs were cold blooded like lizards of today and cold blooded creatures often have been known to be accustom to automatic bodies functions and not decision making unlike mammals and animal do use their brain even as far as problem solving and thinking ahead. If this is true than dinosaurs could be easily endangered to the world evolving because of their inability to cope with it. Therefore they couldn't compete with more efficient life forms and could've been slowly dying off and being endangered and eventually becoming extinct.