Neogaeornis is a controversial prehistoric genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of diving bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

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

Fossil

Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

s found in the Campanian

Campanian

The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...

 to Maastrichtian

Maastrichtian

The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...

 Quiriquina Formation

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.-References:...

 of Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

. It lived about 70-67 million years ago. It remains known from the single tarsometatarsus

Tarsometatarsus

The tarsometatarsus is a bone that is found in the lower leg of certain tetrapods, namely birds.It is formed from the fusion of several bones found in other types of animals, and homologous to the mammalian tarsal and metatarsal bones...

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

Kiel

Kiel is the capital and most populous city in the northern German state of Schleswig-Holstein, with a population of 238,049 .Kiel is approximately north of Hamburg. Due to its geographic location in the north of Germany, the southeast of the Jutland peninsula, and the southwestern shore of the...

, Germany

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

.

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, a member of the flightless and toothed Hesperornithes

Hesperornithes

Hesperornithes is an extinct and highly specialized clade of Cretaceous toothed birds. Hesperornithine birds, apparently limited to former aquatic habitats in the Northern Hemisphere, include genera such as Hesperornis, Parahesperornis, Baptornis, Enaliornis, and probably Potamornis, all...

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

Temperate

In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...

 to warm subtropical 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

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 , though prehistoric species were more widespread.-Classification and evolution:There are five living...

 (loons/divers). Both theories are problematic, as neither group is known from the Southern Hemisphere

Southern Hemisphere

The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...

. The even more controversial supposed loon ancestor Polarornis

Polarornis

Polarornis is a genus of prehistoric bird, possibly a loon. It contains a single species Polarornis gregorii known from incomplete remains of one individual found on Seymour Island, Antarctica, in rocks which are dated to the Late Cretaceous .The discovery of Polarornis gregorii was first announced...

from Seymour Island

Seymour Island

Seymour 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 closer to continental land mass than any other part of that Antarctica. It lies within the section of the island chain that resides off the west side of the...

, Antarctica 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, the first living

N. wetzeli may also be the ancestor to the grebe

Grebe

A grebe is a member of the Podicipediformes order, a widely distributed order of freshwater diving birds, some of which visit the sea when migrating and in winter...

s or Podicipediformes.