Cimolopteryx

Cimolopteryx (meaning "Cretaceous wing") 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. 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.

==Description and history== thumb|left|Size of Cimolopteryx species (lower right) compared to other Maastrichtian birds, [[pterosaurs, and a human]] 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.