Hesperornis

Hesperornis is an extinct genus of large, flightless diving birds from Late Cretaceous North America. Its toothed jaws and powerful legs adapted it to underwater pursuit.

Hesperornithiformes: An extinct order of toothed, flightless diving birds that lived during the Cretaceous. Hesperornis is among the best-known genera in this broader group.
Flightlessness: The inability of an animal to fly, whether inherited or acquired through evolution. Hesperornis had reduced wings and could not fly.
Othniel Charles Marsh: An American paleontologist who described many fossils from the western United States. Marsh named Hesperornis from fossils collected during the nineteenth-century western surveys.
Hesperornis crassipes: A species of Hesperornis named from Late Cretaceous fossils in North America. Its fossil record helps document variation within the genus.
Cretaceous: The geologic period spanning about 145 to 66 million years ago. Hesperornis lived in North America during this period.
Foot-propelled diving: Underwater swimming powered chiefly by strokes of the feet or legs. Hesperornis used its powerful hind limbs to pursue prey underwater.
Kansas Chalk: A Cretaceous marine rock formation in Kansas rich in fossils. Important Hesperornis fossils came from these ancient marine deposits.
Hesperornis gracilis: A species assigned to Hesperornis from Late Cretaceous North American fossils. It is one of the named species used to describe the genus's diversity.
Avialae: The evolutionary group containing birds and their closest extinct relatives. Hesperornis belongs within the broad radiation of bird-line dinosaurs.
Hesperornis regalis: A large species of Hesperornis known from Late Cretaceous North America. This named species provides a concrete example of the genus's anatomy and size.

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Niobrara FormationBroader topic: Its fossils show that toothed diving birds lived in the Niobrara seaway.