 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".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