Presbyornis and the Origin of the Anseriformes (Aves: Charadriomorphae)

Olson, Storrs L., and Alan Feduccia. Presbyornis and the Origin of the Anseriformes (Aves: Charadriomorphae). Smithsonian Contributions to Zoology, number 323, 24 pages, 15 figures, 1980.—Evidence purportedly allying the Anseriformes with the Galliformes is discredited. The discovery of vestigial lamellae in the Anhimidae, in addition to the characters these birds share with the anomalous Australian Magpie Goose (Anseranas), proves their anseriform relationship; within the order Anseriformes, the Anhimidae are highly derived and not representative of the ancestral condition in the order. The abundant Eocene fossil Presbyornis combines the body of a shorebird with a duck-like head and shows the Anseriformes to have evolved from the Charadriiformes. The unique filter-feeding apparatus of Presbyornis and the Anatidae was the key adaptation that led to the radiation of the order Anseriformes. The skull of Presbyornis has its greatest similarity to that of the living Australian duck Stictonetta, which on other grounds has been considered primitive. This suggests that a rearrangement of the subgroups of Anatidae may be needed. The fossil record shows that no certain Anseriformes are known before the early Oligocene, indicating a probable mid-Tertiary date for the major radiation of Anatidae. The ancestors of ducks were Charadriiformes that adapted originally for life in shallow saline lakes, where selection pressure for filter-feeding would have been strong. The Anseriformes should be maintained as a separate order following the Charadriiformes. Presbyornis is considered still to have had a charadriiform grade of morphology and for the present is retained in the Charadriiformes. OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: The coral Montastrea cavernosa (Linnaeus). Library of Congress Cataloging in Publication Data Olson, Storrs L Presbyornis and the origin of the Anseriformes (Aves, Charadriomorphae) (Smithsonian contributions to zoology ; no. 323) Bibliography: p. 1. Anseriformes—Evolution. 2. Presbyornis—Evolution. 3. Birds—Evolution. I. Feduccia, J. Alan, joint author. II. Title. III. Series: Smithsonian Institution. Smithsonian contributions to zoology ; no. 323. QL1.S54 no. 323 [QL696.A5] 591s [568'.3] 80-607065