![]() Some mainstream ornithologists including Smithsonian Institute curator Storrs L. Some dinosaur restorations began to picture dinosaurs with a downy or feathery cover.ĭirect evidence to support the theory was missing, however. In all, over a hundred distinct anatomical features are shared by birds and theropod dinosaurs.īy 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). 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. 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. Ostrom has since become a leading proponent of the theory that birds are direct descendants of dinosaurs. Then, in 1964, John Ostrom discovered a fossilized dinosaur he called Deinonychus antirrhopus, a theropod whose skeletal resemblance to birds seemed unmistakable. 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. The leading dinosaur expert of the time, Richard Owen, disagreed, claiming Archaeopteryx as the first bird outside dinosaur lineage. In 1868 he published On the Animals which are Most Nearly Intermediate between Birds and Reptiles, making the case. He cited skeletal similarities, particularly among some saurischian dinosaurs, fossils of the 'first bird' Archaeopteryx and modern birds. 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. 4 Taxonomy and the inference of feathers in other dinosaurs.3.1 List of dinosaur genera preserved with feathers.They lived around 160 million years ago, alongside early birds and feathered dinosaurs. ![]() They were small animals that probably flitted from tree to tree in forests, and fed on insects. Microscopic studies of the pterosaur feathers revealed pigment-containing structures called melanosomes, whose shape suggests both fossil pterosaurs were a gingery brown colour in life. “The next step out on the family tree is crocodiles, so maybe, just maybe, a palaeontologist will one day find a fossil croc with feathers.” “The most logical conclusion is that feathers go all the way back, beyond even dinosaurs, to a more distant ancestor,” agrees Brusatte. ![]() So maybe the ancestors of these dinosaurs had feathers and lost them. But Benton points out that many mammals, from whales to elephants, have lost most of their hair. The counterargument is that many giant dinosaurs had armour rather than feathers. “That would take the origin back from about 170 million years ago to around 250 million years,” says Benton. Or they evolved in the common ancestor of all these groups. ![]() Either very similar looking feathers evolved independently on at least four occasions: in pterosaurs, in theropod dinosaurs such as velociraptors (which gave rise to birds) and in two groups of plant-eating ornithischian dinosaurs represented by Psittacosaurus and Kulindadromeus. “I think it’s now case closed, pterosaurs had feathers.” “If all I had was a photo of the fluffy stuff on these fossils, and I didn’t know they were attached to a pterosaur, I would probably think they were the feathers of a feathered raptor dinosaur,” says palaeontologist Steve Brusatte of the University of Edinburgh in the UK, who wasn’t involved in the study. They are remarkably similar to the feathers found on many dinosaurs. And the third, found on the wing membranes, branches from the base and resembles down. The second type, found on the head, has side branches. One type, found on the neck, branches at the end in a brush-like manner.
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