''Aegialornis'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of prehistoric apodiform

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 lightweigh ...

s. It formed a distinct

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

, the Aegialornithidae, and was in some ways intermediate between modern

swift Swift or SWIFT most commonly refers to: * SWIFT, an international organization facilitating transactions between banks ** SWIFT code * Swift (programming language) * Swift (bird), a family of birds It may also refer to: Organizations * SWIFT, ...

s and

owlet-nightjar Owlet-nightjars are small crepuscular birds related to the nightjars and frogmouths. Most are native to New Guinea, but some species extend to Australia, the Moluccas, and New Caledonia. A flightless species from New Zealand is extinct. There is ...

s, lacking the more extreme adaptations to an aerial lifestyle that swifts show today, but already having sickle-shaped wings like them. They do not appear to be a direct ancestor of modern swifts, however, but rather a group that retained an overall basal morphology. Altogether, they were not too dissimilar from modern

treeswift Treeswifts or crested swifts are a family, the Hemiprocnidae, of aerial near passerine birds, closely related to the true swifts. The family contains a single genus, ''Hemiprocne'', with four species. They are distributed from India and Southeast ...

s. Fossils of ''Aegialornis'' have been found in Middle to Late

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

deposits of Germany and France. An Early Eocene record from the

Nanjemoy Formation The Nanjemoy Formation is a geologic formation pertaining to both the Wilcox Group and the Pamunkey Group of the eastern United States, stretching across the states of Virginia, Maryland, and District of Columbia. The formation crops out east of ...

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...

, United States (

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496384) is very doubtful, as apodiform birds seem not to have occurred there until after the Eocene. This bone might more properly belong to the Parvicuculidae.Mayr, Gerald & Mourer-Chauviré: A specimen of ''Parvicuculus'' Harrison & Walker 1977 (Aves: Parvicuculidae) from the early Eocene of France. '' Bull. B. O. C.'' 125(4): 299-304
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The taxonomy of the species is quite convoluted, with both the smaller ''A. germanicus'' and the larger ''A. leenhardti'' being sometimes considered

junior synonym The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. * In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linna ...

s of ''A. gallicus'', which in turn is sometimes erroneously assumed to be identical to '' Cypselavus gallicus''. Similarly, ''A. broweri'' is occasionally considered to be based on small individuals of ''A. wetmorei'', and these latter two taxa were recently separated as genus ''Mesogiornis'' (Mlíkovský, 2002); this does not appear to have found general acceptance however. The presumed species ''Aegialornis szarskii'' is now placed in ''

Scaniacypselus ''Scaniacypselus'' is a genus of basal swift from the Eocene of Denmark, Germany and France. Many well preserved specimens still showing plumage were discovered in the Messel Pit near Darmstadt, Germany. ''Scaniacypselus'' had relatively broade ...

''. Which genera apart from the present one should be included in the Aegialornithidae is not quite certain. ''

Primapus ''Primapus'' is an extinct genus of apodiform bird from the Early Eocene of the United Kingdom. Its fossils were found in the London Clay, which was deposited around 50 million years ago. The type species is ''P. lacki''. Sources * ''Fossils' ...

'' belongs either here or is a basal true swift, and ''Cypselavus'' is either an aegialornithid or a treeswift. The latter group is sometimes controversially included in the Aegialornithidae, as are the Jungornithidae, another prehistoric apodiform family that was somewhat intermediate between treeswifts and hummingbirds.

References

External links

Fossil picture.
{{Taxonbar, from=Q4135004 Aegialornithidae Eocene birds Prehistoric bird genera Eocene birds of Europe Fossil taxa described in 1891