 This was particularly true after 1980 when Luis and Walter Alvarez put forward the Alvarez hypothesis claiming that an impact event caused the Cretaceous–Paleogene extinction event, which killed off the non-avian dinosaurs along with many other living things.Also in the early 1980s Jack Sepkoski and David M. Raup published papers with statistical analysis of the fossil record of marine invertebrates that revealed a pattern (possibly cyclical) of repeated mass extinctions with significant implications for the evolutionary history of life.Throughout the 20th century new fossil finds continued to contribute to understanding the paths taken by evolution.