''Neogaeornis'' is a controversial prehistoric

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of diving

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

. The single known species, ''Neogaeornis wetzeli'', was described from

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s found in the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

Quiriquina Formation The Quiriquina Formation is a geological formation in Chile whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.Weishampel, David B; et al. (2004). "Dinosaur distributi ...

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

. It lived about 70-67

million years ago Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...

. It remains known from the single

tarsometatarsus The tarsometatarsus is a bone that is only found in the lower leg of birds and some non-avian dinosaurs. It is formed from the fusion of several bird bones found in other types of animals, and homologous to the mammalian tarsus (ankle bones) a ...

described in 1929 by Lambrecht, and today housed in the Paläontologisches Institut und Museum in

Kiel Kiel ( ; ) is the capital and most populous city in the northern Germany, German state of Schleswig-Holstein. With a population of around 250,000, it is Germany's largest city on the Baltic Sea. It is located on the Kieler Förde inlet of the Ba ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

.Chiappe (1991)

Taxonomy

It is controversial because of its uncertain placement. While clearly related to modern birds, ''N. wetzeli'' might not be a particularly close relative, but rather belong to the

Baptornithidae ''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 disc ...

, a member of the flightless and toothed

Hesperornithes Hesperornithes is an extinct and highly specialized group of aquatic Avialae, avialans closely related to the ancestors of modern birds. They inhabited both marine and freshwater habitats in the Northern Hemisphere, and include genus, genera such ...

. If this is so, ''Neogaeornis'' is among the very youngest records of this lineage, and the first one from the Southern Hemisphere. However, the Hesperornithiformes are known to have been birds of the open epicontinental and

shelf sea A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

s which avoided the outer oceans as surrounded South America at that time. And though apparently somewhat migratory, they are only known from

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

to warm

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...

climates, and it seems that towards the end of the Cretaceous their range shifted polewards. Others consider it a close relative of certain modern birds, such as the

Gaviiformes Gaviiformes () is an order of aquatic birds containing the loons or divers and their closest extinct relatives. Modern gaviiformes are found in many parts of North America and northern Eurasia (Europe, Asia and debatably Africa), though prehistor ...

(loons/divers). Both theories are problematic, as neither group is known from the Southern Hemisphere. The even more controversial supposed loon ancestor ''

Polarornis ''Polarornis'' is a genus of prehistoric bird, possibly an Odontoanserae, anserimorph. It contains a single species ''Polarornis gregorii'', known from incomplete remains of one individual found on Seymour Island, Antarctica, in rocks which are ...

'' from

Seymour Island Seymour Island or Marambio Island, is an island in the chain of 16 major islands around the tip of the Graham Land on the Antarctic Peninsula. Graham Land is the closest part of Antarctica to South America. It lies within the section of the isl ...

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

presents a similar dilemma and ''Neogaeornis'' and there is little consensus about the age of ''Polarornis'', and so all that can be said is that ''Polarornis'' and ''Neogaeornis'' were similarly sized birds with similar lifestyles. Most recent phylogenetic studies seem to favour its position as a basal

loon Loons (North American English) or divers (British English, British / Irish English) are a group of aquatic birds found in much of North America and northern Eurasia. All living species of loons are members of the genus ''Gavia'', family (biolog ...

. Alongside ''

'' and some yet unnamed

Antarctic The Antarctic (, ; commonly ) is the polar regions of Earth, polar region of Earth that surrounds the South Pole, lying within the Antarctic Circle. It is antipodes, diametrically opposite of the Arctic region around the North Pole. The Antar ...

specimens, it seems to suggest a

Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...

n origin for this group. In 2017 a phylogenetic study Agnolín and colleagues have found ''Neogaeornis'' to be stem-

anseriform Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which inc ...

s along with ''

'', '' Australornis'' and ''

Vegavis ''Vegavis'' is a genus of extinct bird that lived in Antarctica during the Maastrichtian stage of the Late Cretaceous. The type and only species is ''Vegavis iaai'', representing one of the earliest known crown group birds. Initially described ...

'' in the family

Vegaviidae Vegaviidae is a proposed extinct family of anseriform birds which lived during the Late Cretaceous and possibly the Paleocene. The monophyly of the family has been questioned by subsequent studies, with the only definitive member ''Vegavis'' know ...

Gerald Mayr Gerald Mayr is a German palaeontologist who is Curator of Ornithology at the Senckenberg Research Institute in Frankfurt am Main, Hesse. He has published extensively on fossil birds, especially the Paleogene avifauna of Europe.Mayr, Gerald (2016). ...

suggested that it is uncertain whether ''Neogaeornis'' belongs to the family since the specimen shows traits of other bird groups including those of podicipediform and gaviiform, but if it were true, then both ''Neogaeornis'' and possibly the closely related '' Antarcticavis'' might represent vegaviids.

References

Bibliography

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Taxonomy

References

Bibliography

Further reading