Dinosaurs, Ornithologists and Paleontology

Controversy exists in the professional paleontology community over the origin and fate of dinosaurs, as well as over the status, if any, of their lineal descendants in the animal kingdom. Ornithologists have also entered the debate in recent years, for the reason that, in 1973 a paleontologist who had researched the bones of the Archaeopteryx lithographica, which had been discovered in Germany in 1861 and which at 150 million years old was considered the first evolved bird, revived an idea first proposed by Thomas Huxley in 1868 that the animal "had inherited many of its features directly from a small meat-eating dinosaur" (Martin, 1998). In other words, long-extinct dinosaurs were the ancestors of birds. One view, indeed, is that dinosaurs never went extinct at all but through the process of evolution merely became reconfigured as birds, specifically a omnivorous variety of the theropod dinosaur. Many ornithologists "bristle" at the idea (Chang, 1998) and insist on the distinction between species.

What has lent strength to the paleontologists' perspective in recent years is the accretion of fossil evidence showing the imprint of feather or featherlike structures. Almost all of the recent evidence appears to have been found in Liaoning Province, China (Chang, 1998; Norell, 2001). One effect of the findings in the field--and of the scientifica debate accompanying them--is that the discipline of cladistics, which is "a method . . . to rank and group organisms according to char

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s to the category of dinosaur predators called dromaeosaurs. The reason M. gui, as the species is often called, has fueled the debate over dino-birds is that the wing structure suggests that the bird's four wings and its abundant distribution of feathers are seen as a possible reason that it might have been able to fly, or anyway almost fly. The feathers on the limbs were asymmetrical. Perkins cites the observation of Richard O. Prum of the University of Kansas that the feathers' vanes were of different widths on either side, a "nuance of design" that is consistent with the view that the feathers "served an aerodynamic purpose" (Perkins, 2003). Prum's view is that M. gui was more or a glider than an outright flier. Similarly, evolutionary biologist Jeremy M.V. Rayner at England's University of Leeds comments that the extra wing size at the hind limbs "would have reduced the angle of its glide and thus increased the distance each glide covered" (Perkins, 2003). There are two theories about how bird flight evolved, known respectively as trees-down and ground-up. The former idea has been adopted those who take the view that birds are "more like cousins than sons or daughters" of dinosaurs, sharing at most a common distant ancestor

Category: Science - D