''Palintropus'' is a prehistoric

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

from the Late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

. A single

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

has been named (''Palintropus retusus'') based on a proximal coracoid from the

Lance Formation The Lance (Creek) Formation is a division of Late Cretaceous (dating to about 69 - 66 Ma) rocks in the western United States. Named after Lance Creek, Wyoming, the microvertebrate fossils and dinosaurs represent important components of the late ...

Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to the s ...

, dated to the latest

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval ...

, million years ago. Coracoids and a proximal scapula of two unnamed species from the upper

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. Campani ...

Dinosaur Park Formation The Dinosaur Park Formation is the uppermost member of the Belly River Group (also known as the Judith River Group), a major geologic unit in southern Alberta. It was deposited during the Campanian stage of the Late Cretaceous, between about 76. ...

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

, dating to between 76.5 and 75 million years ago, are also known.Hope (2002) Pterosauria journal

Initially it was placed in the

wastebin genus Wastebasket taxon (also called a wastebin taxon, dustbin taxon or catch-all taxon) is a term used by some taxonomists to refer to a taxon that has the sole purpose of classifying organisms that do not fit anywhere else. They are typically define ...

''"

Cimolopteryx ''Cimolopteryx'' (meaning "Cretaceous wing"Holtz, Thomas R. Jr. (2008) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages'Winter 2010 Supplementary Information) is a prehistoric bird genus from the Late Creta ...

"''.

Pierce Brodkorb William Pierce Brodkorb (September 29, 1908, Chicago – July 18, 1992, Gainesville, Florida) was an American ornithologist and paleontologist. Interested in birds since childhood, he was taught to prepare birds at the age of 16. Later, he rec ...

assigned it its current name, first affiliating it with ''

Apatornis ''Apatornis'' is a genus of prehistoric birds endemic to North America during the late Cretaceous. It currently contains a single species, ''Apatornis celer'', which lived around the Santonian-Campanian boundary, dated to about 83.5 million years ...

'' in 1963, and establishing its current genus in 1970.Brodkorb (1970) Its relationships are not well determined, mainly due to the paucity of material. Several major theories have been established: Like many of the birds of the subtropical coastlands of the

Western Interior Seaway The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, and the Western Interior Sea) was a large inland sea that split the continent of North America into two landmasses. The ancient sea ...

- maybe a bit like eastern Australia today - it is sometimes believed to be an early member of the

Charadriiformes Charadriiformes (, from ''Charadrius'', the type genus of family Charadriidae) is a diverse order of small to medium-large birds. It includes about 390 species and has members in all parts of the world. Most charadriiform birds live near water an ...

(waders, gulls, auks, etc.; see also " Graculavidae"). However, an alternate theory is that it is a

galliform Galliformes is an order of heavy-bodied ground-feeding birds that includes turkeys, chickens, quail, and other landfowl. Gallinaceous birds, as they are called, are important in their ecosystems as seed dispersers and predators, and are often ...

, perhaps a quercymegapodiid. In 2009, Longrich and colleagues proposed that ''Palintropus'' is a primitive bird related to ''

Apsaravis ''Apsaravis'' is a Mesozoic bird genus from the Late Cretaceous. The single known species, ''Apsaravis ukhaana'', lived about 78 million years ago, in the Campanian age of the Cretaceous period. Its fossilized remains were found in the Camel's ...

''. They conducted the first

cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived char ...

analysis of the remains, and found this to be the most likely hypothesis, suggesting ''Palintropus'' warrants inclusion in the newly established Palintropiformes.Longrich, N. (2009). "An ornithurine-dominated avifauna from the Belly River Group (Campanian, Upper Cretaceous) of Alberta, Canada." ''Cretaceous Research'', 30(1): 161-177.

Footnotes

References

* (1970): The generic position of a Cretaceous bird. Quarterly Journal of the Florida Academy of Science. 32(3), 239–240. * (2002): '
The Mesozoic radiation of Neornithes
in Chiappe and Witmer, eds. Mesozoic Birds: Above the Heads of Dinosaurs. 339–388. Bird genera Prehistoric euornitheans Late Cretaceous birds of North America {{paleo-bird-stub