Ichthyornis was a prehistoric bird that lived during the late Cretaceous period, around 150 million years ago. It is known for its unique combination of features, displaying characteristics of both modern birds and reptiles. Fossils of Ichthyornis have been found primarily in North America, providing valuable insights into the evolution of avian species. This bird was about the size of a modern seagull and had a beak filled with teeth, which is a trait not seen in today's birds. Ichthyornis is significant in the study of paleontology as it helps scientists understand the transition from dinosaurs to modern birds, highlighting the evolutionary changes that occurred during that time.