dko_scOH - 10/26/2018 06:44 There had been other hypotheses as to why the dinosaurs went extinct after such a long reign. Then, Alvarez upended all of them when he found a thin layer of shocked quartz and iridium at the same geological age in different places around the world -- precisely at the point of mass extinction. The fact that decent ideas gave way to a better idea is proof (if you needed it) that science does not push ideas as final. Rather, it changes as needed to incorporate new information.