An underwater impact crater alone does not prove that an asteroid killed the dinosaurs, as there could be other causes of an underwater impact crater apart from an asteroid collision. There are multiple lines of evidence that suggest an asteroid impact may have contributed to the extinction of dinosaurs, including the Chicxulub impact crater, the presence of a thin layer of sediment called the K-T boundary that contains high concentrations of the element iridium, which is commonly found in asteroids, and the presence of fossilized impact ejecta such as spherules in marine sediments from the same time period. These pieces of evidence, along with other geological and paleontological data, support the theory of an asteroid impact being a major factor in the extinction of dinosaurs.