wikipedia & feathered dinosaurs

by Hugh

In the fall of 2004, I quit my job consulting in the renewable energy industry in order to focus on writing. In addition to fiction-writing, I worked on a research/writing contract to develop an exhibit on dinosaurs (part of which is still online) for the Canadian Museum of Nature.

I’d never used Wikipedia much before, but I used it frequently on that project as a starting point for research. It was an excellent resource (to be backed up with others, of course), and since it was so useful, I thought I should contribute. I got hooked.

So it’s nice to see, three-and-a-half years later, that the article on feathered dinosaurs, for which I was the second editor, still contains a pretty good summary, I think, that I wrote about the history of these peculiar fossils:

Shortly after the 1859 publication of Charles Darwin’s The Origin of Species, British biologist and evolution-defender Thomas Henry Huxley proposed that birds were descendants of dinosaurs. He cited skeletal similarities, particularly among some saurischian dinosaurs, fossils of the ‘first bird’ Archaeopteryx and modern birds. In 1868 he published On the Animals which are Most Nearly Intermediate between Birds and Reptiles, making the case. The leading dinosaur expert of the time, Richard Owen, disagreed, claiming Archaeopteryx as the first bird outside dinosaur lineage. For the next century, claims that birds were dinosaur descendants faded, with more popular bird-ancestry hypotheses including ‘crocodylomorph’ and ‘thecodont’ ancestors, rather than dinosaurs or other archosaurs.

In 1964, John Ostrom described Deinonychus antirrhopus, a theropod whose skeletal resemblance to birds seemed unmistakable. Ostrom has since become a leading proponent of the theory that birds are direct descendants of dinosaurs. Further comparisons of bird and dinosaur skeletons, as well as cladistic analysis strengthened the case for the link, particularly for a branch of theropods called maniraptors. Skeletal similarities include the neck, the pubis, the wrists (semi-lunate carpal), the ‘arms’ and pectoral girdle, the shoulder blade, the clavicle and the breast bone. In all, over a hundred distinct anatomical features are shared by birds and theropod dinosaurs.

Other researchers drew on these shared features and other aspects of dinosaur biology and began to suggest that at least some theropod dinosaurs were feathered. The first restoration of a feathered dinosaur was Sarah Landry’s depiction of a feathered “Syntarsus” (now renamed Megapnosaurus or considered a synonym of Coelophysis), in Robert T. Bakker’s 1975 publication Dinosaur Renaissance.[2] Gregory S. Paul was probably the first paleoartist to depict maniraptoran dinosaurs with feathers and protofeathers, starting in the late 1980s.

By the 1990s, most paleontologists considered birds to be surviving dinosaurs and referred to ‘non-avian dinosaurs’ (those that went extinct), to distinguish them from birds (aves or avian dinosaurs). Direct evidence to support the theory was missing, however. Some mainstream ornithologists, including Smithsonian Institution curator Storrs L. Olson, disputed the links, citing the lack of fossil evidence for feathered dinosaurs.

Fossil evidence

After a century of hypotheses without hard evidence, particularly well-preserved (and legitimate) fossils of feathered dinosaurs were discovered during the 1990s and 2000s. The fossils were preserved in a Lagerstätte — a sedimentary deposit exhibiting remarkable richness and completeness in its fossils — in Liaoning, China. The area had repeatedly been smothered in volcanic ash produced by eruptions in Inner Mongolia 124 million years ago, during the Early Cretaceous Period. The fine-grained ash preserved the living organisms that it buried in fine detail. The area was teeming with life, with millions of leaves and the oldest known angiosperms, insects, fish, frogs, salamanders, mammals, turtles, lizards and crocodilians discovered to date.

The most important discoveries at Liaoning have been a host of feathered dinosaur fossils, with a steady stream of new finds filling in the picture of the dinosaur-bird connection and adding more to theories of the evolutionary development of feathers and flight.

To improve the article, head on over to wikipedia. Kinda nice to know that for 95% (50%? 80%?) of the young, English-speaking, students of paleontology in the world, it’s my text that might first introduce them to feathered dinosaurs.