Sunday, September 18, 2011

Dinosaur Feathers in Amber

Image credit: McKellar et al./Science View more: HERE

Earlier this week, a paper published in the Journal Science described a collection of dinosaur feathers suspended in amber. The 11 samples described in the paper were found amongst a collection of some 4,000 amber deposits held in various museums in Alberta, Canada. These ancient feathers were trapped in amber (fossilized tree resin) around 70-80 million years ago, sometime during the late Cretaceous period.

According to the paper's abstract, the structure of the protofeathers found in the deposits, demonstrate several different evolutionary adaptations of the feather, including those used in flight, as well as underwater diving. And because of their preservation inside amber, these specimens also reveal the actual pigmentation of the feathers; which range in color from brown to black.

For those of you who haven't kept up with your paleontology or evolutionary biology very well over the years, and find all this talk of dinosaurs and feathers a bit confusing; and because it's been a while since I indulged myself with a lengthy science entry, I offer the following:

The dominant view in science today is that modern birds are in fact, dinosaurs. More specifically, birds are considered by most scientists to be modern examples of a family of dinosaurs known as theropods, which evolved during the Mesozoic era ( 250 to 65 million years ago). This idea, or at least the idea that modern birds were descended from dinosaurs, was first proposed shortly after the publication of Charles Darwin's origin of species in 1859, by British biologist Thomas H Huxley.

Huxley came to believe in the dinosaur's ancestry to birds, after comparing the anatomy of the "first bird" fossil, Archaeopteryx Lithographica, with that of a small theropod dinosaur called Comsognathus, which he noted were -aside from Archaeopteryx's feathers and hands- extremely similar to one another. Huxley made his case for the link between the two animals, and their likely ancestry to modern birds in, "On the Animals which are most nearly intermediate between Birds and Reptiles" , published in "The Annals and Magazine of Natural History", in 1868.

At the time of Huxley's research the popular consensus was that dinosaurs had not developed into birds, but that birds -like every other modern species- had their own lineage; one which had arisen completely independently from dinosaurs. Archaeopteryx, therefore, represented the first primitive form of the species now known as birds, rather than a transition between dinosaur and bird, as Huxley had asserted. As a result of this opposition to the Darwinian notion of transmutation, Huxley's theory faded from interest, and the belief that birds and dinosaurs had evolved separately, remained the most popular scientific view for nearly the next hundred years.

But Interest in Huxley's theory would finally be fully revived in 1964, when American paleontologist John H. Ostrom, conducted his own anatomical comparisons of modern birds and dinosaurs. In the years which followed, others began to conduct similar comparative analysis, and by the late 1970's, many had not only come to accept the relationship of birds to ancient theropods, but some had also begun to speculate that early theropods might also have had feathers. By the mid 1990's, the notion that modern birds were, in fact, living dinosaurs, had largely become accepted fact, and the assertion that their ancient counter-parts had most likely been feathered as well, was also widely believed. But this belief was still a speculative one at this point, as little to no fossil evidence of feathered dinosaurs had yet been found.

But in the past twenty years, dozens of new fossils and various other major finds have also been added to the list of evidence in the case for feathered theropods. From simple impressions found around fossil remains, to quill knobs (the anchor point for wing feathers) found on the forelimb of certain fossilized specimens. In 2010, researchers even managed to determine the color of some of these feathers, by analyzing fossilized melanosomes, found in the fossils of birds and dinosaurs from northeastern China.

In the years since Huxley first proposed an evolutionary link between dinosaurs and modern birds, countless new discoveries have been made which support his theory. And though now widely accepted as scientific fact, there will always be those who question the evolutionary link between birds and ancient theropods; both legitimately and otherwise. But when confronted with the growing fossil evidence, and now, the feathers themselves; perfectly preserved in amber. It seems undeniable that the answer to the question, " Were there feathered dinosaurs?" at least, is a definitive, yes.

Cue the rambling creationist counter-point in...


Source: Wired Science , The Journal Science, Wikipedia, New World Encylopedia

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