Feathers may not have a]ways separated the world of birds from other animals, in fact, the first feathers did not necessarily herald the age of animal flight―and here is where the feathers fly between two opposing camps of paleontologists. One side argues that feathers initially evolved in a small group of two-legged, carnivorous dinosaurs. Luis Chiappe of the Natural History Museum of Los Angeles County believes that early forerunners of feathers initially served purposes other than flight, such as attracting potential mates and maintaining body heat.
Computer simulations utilized to analyze aerodynamics show that flightless dinosaurs with feathered, wing-like appendages would have been able to run faster and make quicker turns if they flapped their wings, enabling them to catch prey or escape predators. This theory presupposes, of course, that feathered dinosaurs were the early ancestors of modern birds.
Other paleontologist, argue against this “ground up” theory, saying that feathers more likely evolved “from the trees down.” Advocates of the latter theory hold that the evolution of modern feathers und the ability to fly happened simultaneously. Some believe that small reptiles living in trees evolved stubby projections, which smoothed airflow on their skin and enabled them to jump quickly away from predators. Reptiles that developed longer filaments from these projections could jump faster and farther. Dominique Homberger, an evolutionary biologist at Louisiana State University, maintains that these precursors to feathers probably did net serve all the purposes that modem feathers do, but that they did provide some clear survival advantages.
There are other contentious feather issues among paleontologists. Some rely exclusively on analyses of fossil records to determine how feathers may have evolved. Others focus their attention on modern birds. The members of the first camp search for evolutionary relationships between various organisms by analyzing shared characteristics in fossilized remains, a science called cladistics.
They construct evolutionary family trees based on the analysis of such shared traits as general body structure, the number and shape of bones, and the type of skin covering. The other scientists consider it foolish to restrict investigation to fossils. This group studies the characteristics of modern birds for clues as to how feathers may have evolved in ancient predecessors.
The debate between the fossil-focused and less restricted groups is heated. Chiappe, a proponent of the cladistics-camp, calls his opponents “the arm-waving-school of speculating and looking for what's intuitively pleasing.” “Nothing's intuitively pleasing,”he says, “until I see it in the fossil record.” The opposing camp argues that fossil records are simply too spotty to provide a clear picture of what really happened. The situation is complicated by the fact that the earliest known bird fossil, the famous Archaeopteryx, appears to already have feathers.
If feathers did indeed evolve from something else, the fossil record has yet to produce conclusive evidence as to how or why. Paleontologists of both camps eagerly await the discovery of bird fossils that predate Archaeopteryx , in hopes that the findings will prove their respective views and close the debate once and for all.