Hesperornithes

Hesperornis (from Ancient Greek ἕσπερος (hésperos), meaning "western", and ὄρνις (órnis), meaning "bird") is a genus of cormorant-like ornithuran that spanned throughout the Campanian age, and possibly even up to the early Maastrichtian age, of the Late Cretaceous period. One of the lesser-known discoveries of the paleontologist O. C. Marsh in the late 19th century Bone Wars, it was an early find in the history of avian paleontology. Locations for Hesperornis fossils include the Late Cretaceous marine limestones from Kansas and the marine shales from Canada. Nine species are recognised, eight

Hesperornithes is an extinct and highly specialized group of aquatic avialans closely related to the ancestors of modern birds. They inhabited both marine and freshwater habitats in the Northern Hemisphere, and include genera such as Hesperornis, Baptornis, Parahesperornis, Enaliornis, and Potamornis, all strong-swimming, predatory divers. Many of the species most specialized for swimming were completely flightless. The largest known hesperornithean, Canadaga arctica, may have reached a maximum adult length of .

Baptornis ("diving bird") is a genus of flightless, aquatic birds from the Late Cretaceous, some 87-80 million years ago (roughly mid-Coniacian to mid-Campanian faunal stages). The fossils of Baptornis advenus, the type species, were discovered in Kansas, which at its time was mostly covered by the Western Interior Seaway, a shallow shelf sea. It is now known to have also occurred in today's Sweden, where the Turgai Strait joined the ancient North Sea; possibly, it occurred in the entire Holarctic.

Brodavis is a genus of freshwater hesperornithiform birds known from the Late Cretaceous (possibly Campanian and Maastrichtian stage) of North America and Asia. It was first described and named by Larry D. Martin, Evgeny N. Kurochkin and Tim T. Tokaryk in 2012 and assigned to a new monogeneric family, Brodavidae. Four species were described and assigned to Brodavis.

Parahesperornis is a genus of prehistoric flightless birds from the Late Cretaceous. Its range in space and time may have been extensive, but its remains are rather few and far between, at least compared with its contemporary relatives in Hesperornis. Remains are known from central North America, namely the former shallows of the Western Interior Seaway in Kansas. Found only in the upper Niobrara Chalk, these are from around the Coniacian-Santonian boundary, 85–82 million years ago (mya). thumb|left|Photograph of scutes and feather impressions of the tarsal region of specimen (KUVP 2287) publ

Potamornis is a prehistoric bird genus that dated back to the late Maastrichtian age of the late Cretaceous period. Its scrappy remains were found in the Lance Formation at Buck Creek, USA, and additional possible remains were found in the upper Hell Creek Formation of Montana, dated to the Danian age of the Paleogene period, though these may have been reworked. A single species was named and described in 2001: Potamornis skutchi.

Canadaga (meaning "Canadian bird") is a flightless bird genus from the Late Cretaceous. The single known species is Canadaga arctica. It lived in the shallow seas around what today is Bylot and Devon Islands in Nunavut, Canada. Its fossils were found in rocks dated to the Campanian to mid-Maastrichtian age, about 67 million years ago. It was found in the Kanguk Formation

Enaliornis is a genus of hesperornithine which lived during the late Albian to the early Cenomanian, making them the oldest known hesperornithines. Fossils have been found near Cambridge, England. Due to its lack of certain hesperornithid apomorphies, they were much more "conventional" birds and were initially held to be Gaviiformes (loons/divers).

Fumicollis is a genus of prehistoric flightless birds from the Late Cretaceous (Coniacian-Santonian) Niobrara Chalk of Kansas.

Asiahesperornis is a prehistoric foot-propelled diving toothed flightless bird genus from the Late Cretaceous. The single known species is Asiahesperornis bazhanovi. It lived in what today is Kazakhstan, at its time the shores of the shallow Turgai Sea.

Chupkaornis (meaning "eastern bird") is a genus of prehistoric flightless birds from the Late Cretaceous (Coniacian-Santonian) Kashima Formation of Hokkaido, Japan. The type species is Chupkaornis keraorum.

Judinornis is a genus of prehistoric flightless birds from the late Cretaceous period. The single known species is Judinornis nogontsavensis. Its fossils have been found in Nemegt Formation rocks of southern Mongolia, and though the age of these deposits is not fully resolved, Judinornis probably lived some 70 million years ago during the early Maastrichtian.

Pasquiaornis is a prehistoric seabird genus of the Hesperornithes. It lived in the Late Cretaceous, during the late Cenomanian between 95 and 93 million years ago in North America. Two species, P. hardiei and P. tankei, were described in 1997 by Tim Tokaryk, Stephen Cumbaa and John Storer.