Ichthyornis lived mainly in the seashores of the Western Seaway. Its diet mainly consisted of fish, small animals, and carcasses. It was a toothed bird, having small sharp teeth lined in its jaws. Ichthyornis had a similar echological role to modern day, gulls, petrels, and skimmers. Ichthyornis was around 24 centimetres long with a skeletal wingspan of about 43 centimetres.