''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 Cretaceous Period. It is currently thought to contain only a single species, ''Cimolopteryx rara''. The only specimen confidently attributed to ''C. rara'' was found in the Lance Formation of Wyoming, dating to the end of the Maastrichtian age, which ended about million years ago.Hope, S. (2002). "The Mesozoic radiation of Neornithes." Pp. 339-388 in Chiappe, L.M. and Witmer, L. (eds.), ''Mesozoic Birds: Above the Heads of Dinosaurs.'' The dubious species "''Cimolopteryx" maxima'' has been described from both the Lance Formation and the Hell Creek Formation of Montana. The humeral end of a left coracoid from the Frenchman Formation of southern Saskatchewan has also been attributed to the genus.Tokaryk, T.T. and James, P.C. 1989. Cimolopteryx sp. (Aves: Charadriiformes) from the Frenchman Formation (Maastrichtian), Saskatchewan. Canadian Journal of Earth Sciences, vol. 26, p. 2729-2730.

Description and history

''Cimolopteryx'' was a fairly small bird, with a maximum size about equal to that of a small gull. It is known almost exclusively from a number of coracoids (a bone in the shoulder girdle). These have a distinct enough anatomy, however, to allow it to be distinguished from other birds, and even for distinct species to be recognized. The first such coracoid to be found (specimen number YMP 1845, in the collections of the Peabody Museum of Natural History) was first mentioned and informally named by paleontologist Othniel Charles Marsh in the footnote of an 1889 paper, but it was not validly described by him until 1892. Marsh also described a second species in the same paper, which he named ''Cimolopteryx retusa'', but this has since been recognized as a different kind of bird and reclassified as ''

Palintropus retusus ''Palintropus'' is a prehistoric bird genus from the Late Cretaceous. A single species has been named (''Palintropus retusus'') based on a proximal coracoid from the Lance Formation of Wyoming, dated to the latest Maastrichtian, million years ag ...

''.

Classification and species

The classification of various species assigned to the genus ''Cimolopteryx'' has changed over the years, and many species once thought to belong to this genus have been reclassified or deemed indeterminate. As of a re-evaluation of the fossil remains in 2002 by Sylvia Hope, at most five species were recognized: ''Cimolopteryx rara'', ''C. petra'', ''C. maxima'', ''C. minima'', and one yet-unnamed species. ''C. rara'' and ''C. petra'' were considered almost identical, and found in the same environments (the Lance and Frenchman formations), but differed in size, with ''C. petra'' smaller than ''C. rara''. In a 2009 review, Nicholas Longrich synonymized them as the same species, dismissing the size difference as possibly based on sex or growth stage.Longrich, N. (2009). "An ornithurine-dominated avifauna from the Belly River Group (Campanian, Upper Cretaceous) of Alberta, Canada." ''Cretaceous Research'', 30(1): 161-177. However, Longrich reversed his position following a 2011 analysis of Lancian birds, in which he and co-authors considered all four named species to be distinct.Longrich, N.R., Tokaryk, T. and Field, D.J. (2011). "Mass extinction of birds at the Cretaceous–Paleogene (K–Pg) boundary." ''Proceedings of the National Academy of Sciences'', 108(37): 15253-15257. ''C. minima'' and ''C. petra'' were transferred to the new genus ''

Lamarqueavis ''Lamarqueavis'' is an extinct genus of prehistoric birds from the Cimolopterygidae known from Late Cretaceous-aged rocks from Argentina, Canada, and the United States. The type species, ''L. australis'', was named in 2010 and is based on the ho ...

'' by Federico Agnolin in 2010, based on their similarity to the South American species ''L. australis''. An additional species from the much earlier Dinosaur Park Formation of Alberta has also since been re-evaluated as a probable species of ''Lamarqueavis'' rather than ''Cimolopteryx''. "''Cimolopteryx''" ''maxima'' was about twice the size of ''C. rara'', but not enough of its anatomy is known to confidently determine if it belongs to ''Cimolopteryx'' or a different genus. In 2011, Longrich concluded that it was probably distinct, but did not name a new genus for it. Several collections of material that is similar to ''Cimolopteryx'' were referred to by Hope as undetermined species, which lack enough unique characteristics to be properly identified, and these may or may not belong to ''Cimolopteryx''. Hope regarded ''Cimolopteryx'' as a likely member of the modern bird group Charadriiformes, which includes a diverse array of shorebirds. However, since all species are known only from parts of the shoulder girdle and wing bone fragments, this classification is tentative, and a phylogenetic analysis failed to resolve the exact relationships of the many fragmentary Lancian-age bird species. Agnolin looked at anatomical similarities between the various species' coracoid bones, and concluded that ''Cimolopteryx'' and ''Lamarqueavis'' could be grouped together, along with ''

Ceramornis ''Ceramornis'' is a prehistoric bird genus from the Late Cretaceous. It lived shortly before the Cretaceous–Paleogene extinction event in the Maastrichtian, some Longrich, N. (2009). "An ornithurine-dominated avifauna from the Belly River Group ...

'', in a distinct family, the

Cimolopterygidae Cimolopterygidae is an extinct family of ornithurines known from the Late Cretaceous epoch. Remains attributed to cimolopterygids have been found in the Frenchman Formation of Saskatchewan, the Lance Formation of Wyoming, the Fox Hills Formation ...

References

{{Taxonbar, from=Q5120156 Prehistoric bird genera Late Cretaceous birds of Asia Late Cretaceous birds of North America Taxa named by Othniel Charles Marsh Fossil taxa described in 1892 Prehistoric ornithurans