644 A CENTURY OF PROGRESS IN THE NATURAL SCIENCES 



tons of nearly 800 species of living birds for comparison. The illustrations are 

 accurate enough to serve as the basis of comparison by critical modern workers. 

 The first important contribution to the study of fossil birds in America was 

 made in 1870 by 0. C. Marsh (b. 1831, d. 1899). In 1872 Marsh announced the 

 discovery of the Cretaceous toothed bird, Hesperornis regalis. Marsh continued 

 to describe avian fossils and in 1880 published a monograph on the Cretaceous 

 toothed birds of North America. Marsh described a total of 40 species of fossil 

 birds during his lifetime. 



Edward Drinker Cope (b. 1840, d. 1897), Marsh's famous rival, described 

 his first avian fossils in 1871 and the giant Eocene Diatryma from New Mexico 

 in 1876. 



One of the most prolific writers on osteology and paleornithology was Robert 

 W. Shufeldt (b. 1850, d. 1934). In 1891 he began his descriptions of fossil birds, 

 which were to number 43 species, more than the total of any other North Ameri- 

 can worker to date. 



In South America, Florentino Ameghino (b. 1854, d. 1911) described (1891) 

 the gigantic flightless ]\Iiocene bird Phororhacos, which stood at least seven feet 

 tall and had an enormous raptorial beak. In 1895 Ameghino's book on the fossil 

 birds of Patagonia appeared. 



From the lower Eocene beds near Croyden, England, E. T. Newton described 

 (1886) a huge flightless bird, Gastornis, larger than an ostrich, which may be 

 related to the ducks and geese (Swinton, 1934). 



Most of the avian fossils discovered before 1909 were those of large, flightless 

 species. This is not surprising, for flying birds are less likely to become ensnared 

 in natural traps and the bones of small birds are so fragile as to reduce the 

 chances of intact preservation in ordinary sediments. In 1909 Loye Holmes 

 Miller began the study of the abundant Pleistocene material preserved in the 

 asphalt traps of Rancho La Brea, McKittrick, and Carpenteria in southern 

 California. Among the numerous bones of large raptors and scavengers were 

 thousands of skeletal elements belonging to small passerines. As a result of the 

 studies by Loye Miller, and later by Hildegarde Howard and Alden Miller, the 

 Pleistocene avifauna of California is the most completely known fossil avifauna 

 in the world. From Rancho La Brea alone 105 species have been identified. 



Since 1920 the most active paleornithologist in North America has been Alex- 

 ander Wetmore. In 1921 he described an owl from the Eocene of Wyoming and 

 has since described a number of Tertiary birds, primarily from the Miocene and 

 Pliocene. His check-list (1940) of the fossil birds of North America includes 165 

 forms which are still living and 184 extinct species. This list has increased but 

 slightly since 1940. 



Two valuable references to avian fossils have appeared in recent years. In 

 1926 Gerhard Heilmann's The Origin of Birds presented the results of his studies 

 on the relationships between reptiles and birds. Heilmann amassed anatomical 

 and embryological evidence to support the idea of the reptilian origin of birds. 

 His book contains valuable and detailed studies on Archeopteryx and xircheornis. 

 The Handbuch der Palaeornitkologie (1933) by Kalman Lambrecht provides 

 a review of the world-wide knowledge of fossil birds. 



One consequence of the development of knowledge of fossil birds has been 

 speculation as to the origin of flight. Marsh (1880) suggested a tree-dwelling 



