Studies on the Muscles of the Pelvic Appendage in Birds II: The Heterogeneous Order Falconiformes

Abstract

Dissections were made of representatives of the following genera: Cathartes, Coragyps, Sagittarius, Accipiter, Buteo, Aquila, Circus, Pandion and Falco. Detailed comparisons are made of the entire leg musculature. Conclusions: Pandion is allied to the hawks and falcons but differs enough to warrant placing it in a separate suborder, Pandiones, equal in rank with Falcones; the Cathar-tidae, Sagittarius and typical falconiform birds may represent 3 unrelated evolutionary lines, since the pelvic musculature amplifies the many differences already known to exist between these groups. It is recommended that these birds be placed in 3 separate orders, Cathartidiformes, Sagittariiformes and Falconiformes. No important changes should be made in the" muscle names used by Gadow and Furbringer except on the basis of extensive studies of homologies embracing many different orders of birds. It is highly desirable that additional material be examined, especially genera of Accipitridae and Falconidae not available in this study.