''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 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 ...

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 ...

from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

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 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 lates ...

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

, dating to the end of the

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 ...

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 The Hell Creek Formation is an intensively studied division of mostly Upper Cretaceous and some lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana. The Formation (stratigraphy), formation s ...

Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...

. The

humeral The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of ...

end of a left

coracoid A coracoid is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is present as part of the scapula, but this is n ...

from the

Frenchman Formation The Frenchman Formation is a stratigraphic unit of Late Cretaceous (late Maastrichtian) Geochronology, age in the Western Canadian Sedimentary Basin, Western Canada Sedimentary Basin. It is present in southern Saskatchewan and the Cypress Hills (C ...

of southern

Saskatchewan Saskatchewan is a Provinces and territories of Canada, province in Western Canada. It is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and to the south by the ...

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 Gulls, or colloquially seagulls, are seabirds of the subfamily Larinae. They are most closely related to terns and skimmers, distantly related to auks, and even more distantly related to waders. Until the 21st century, most gulls were placed ...

. 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 The Peabody Museum of Natural History at Yale University (also known as the Yale Peabody Museum of Natural History or the Yale Peabody Museum) is one of the oldest, largest, and most prolific university natural history museums in the world. It ...

) was first mentioned and informally named by paleontologist

Othniel Charles Marsh Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of paleontology. A prolific fossil collector, Marsh was one of the preeminent paleontologists of the nineteenth century. Among his legacies are the discovery or ...

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''.

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'' 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 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 ...

, 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 genus of ornithuran dinosaurs 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 Rive ...

'', in a distinct family, the

Cimolopterygidae Cimolopterygidae is an extinct family of ornithurine, ornithuran dinosaurs 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 ...

References

{{Taxonbar, from=Q5120156 Cimolopterygidae Late Cretaceous dinosaurs of Asia Late Cretaceous dinosaurs of North America Fossil taxa described in 1892 Taxa named by Othniel Charles Marsh