“When one reads about Tyrannosaurus and Brontosaurus, one is not dealing with species, like lions or African elephants. Instead, these are genera, a group of animal species. For example, the lion is in the genus Panthera. Species of Panthera include the lion Panthera leo, the tiger P. tigris, and the leopard P. pardus, among others. So saying Tyrannosaurus is much like saying "the big cats".”