A group of extinct flying birds known exclusively from the latest stages of the Cretaceous (80–65 million years ago) in North America. Along with Hesperornithiformes, Ichthyornithiforms are some of the earliest nonmodern bird taxa known to science. Indeed, alongside Archaeopteryx (from much earlier Jurassic rocks in Germany, about 140 million years old), the ichthyornithiformes Ichthyornis, Apatornis, and their kin formed the basis for knowledge of avian evolution for almost a century. Although the fossil record of these birds has improved in recent years, Ichthyornithiformes are still poorly understood.