9 - The origin and early radiation of birds

Summary

Historical perspective

According to Fisher (1967), the first described avian paleospecies was Larus toliapicus (Konig 1825). Thus, the story of fossil birds barely exceeds 150 years, and the 100 years of the American Ornithologists' Union include nearly two-thirds of this. During most of this time, a major burden for paleornithologists has been a lack of comparative skeletons of recent birds. We are now beginning to solve this problem, and modern collections exist with thousands of skeletons covering about two-thirds of the world's species.

The other major problem is the incompleteness of most avian fossils. Fragmentary materials rarely contribute to improving avian systematics and thus limit the impact of paleornithology. The few studies that have used excellent specimens (Marsh 1880; Wellnhofer 1974; Harrison and Walker 1976a; Martin and Tate 1976; Olson 1977), illustrate how much more convincing conclusions are when based on more than one skeletal element. Such studies are possible for less than 10% of the total fossil record of birds, and studies of distribution, both geographic and temporal, must rely on less complete specimens.

Fisher (1967) summarized the distribution of fossil birds and estimated the early avian diversification. Shufeldt and Lambrecht were among the first to estimate the diversity of past avifaunas. Shufeldt realized knowing the osteology of Recent birds was fundamental to understanding fossil ones, and he made numerous osteological contributions (Shufeldt 1909).