10 Phylogeny and the inference of feathers in other dinosaurs.9.1 List of dinosaur genera preserved with evidence of feathers.8 Ornithischian integumentary structures.5.1 BADD, BAND, and the Birds Came First hypothesis.3.7 Homology and comparison to modern feathers.1.4 Modern research and feathered dinosaurs in China.1.3 Ostrom, Deinonychus and the Dinosaur Renaissance.The fossil feathers of one specimen, Shuvuuia deserti, have even tested positive for beta-keratin, the main protein in bird feathers, in immunological tests. Most are from the Yixian Formation in China. Today there are more than twenty genera of dinosaurs with fossil feathers, nearly all of which are theropods. Fossils of Archaeopteryx include well-preserved feathers, but it was not until the early 1990s that clearly nonavian dinosaur fossils were discovered with preserved feathers. This became the mainstream view until the 1970s, when a new look at the anatomical evidence (combined with new data from maniraptoran theropods) led John Ostrom to successfully resurrect the dinosaur hypothesis. Heilmann argued that birds could not have descended from dinosaurs (predominantly because dinosaurs lacked clavicles, or so he thought), and he therefore favored the idea that birds originated from the so-called ' pseudosuchians': primitive archosaurs that were also thought ancestral to dinosaurs and crocodilians. This view remained fairly popular until the 1920s when Gerhard Heilmann's book The Origin of Birds was published in English. Small size (<1 kg) and arboreal habits seem to have arisen fairly late during dinosaurian evolution, and only within maniraptora.īirds were originally linked with other dinosaurs back in the late 1800s, most famously by Thomas Huxley. Based on what is known of the dinosaur fossil record, paleontologists generally think that most of dinosaur evolution happened at relatively large body size (a mass greater than a few kilograms), and in animals that were entirely terrestrial. Together, these fossils represent an important transition between dinosaurs and birds, which allows paleontologists to piece together the origin and evolution of birds.ĭespite integumentary structures being limited to non-avian dinosaurs, particularly well-documented in maniraptoriformes, fossils do suggest that a large number of theropods were feathered, and it has even been suggested that based on phylogenetic analyses, Tyrannosaurus at one stage of its life may have been covered in down-like feathers, although there is no direct fossil evidence of this. Less than two dozen species of dinosaurs have been discovered with direct fossil evidence of plumage since the 1990s, with most coming from Cretaceous deposits in China, most notably Liaoning Province. A substantial amount of evidence demonstrates that birds are the descendants of theropod dinosaurs, and that birds evolved during the Jurassic from small, feathered maniraptoran theropods closely related to dromaeosaurids and troodontids (known collectively as deinonychosaurs). Since then, the term "feathered dinosaurs" has widened to encompass the entire concept of the dinosaur–bird relationship, including the various avian characteristics some dinosaurs possess, including a pygostyle, a posteriorly oriented pelvis, elongated arms and forelimbs and clawed hand, and clavicles fused to form a furcula. Feathered dinosaurs first came to realization after it was discovered that dinosaurs are closely related to birds. įeathered dinosaurs is a term used to describe dinosaurs, particularly maniraptoran dromaeosaurs, that were covered in plumage either filament-like intergumentary structures with few branches, to fully developed pennaceous feathers complete with shafts and vanes. An artist's depiction of a feathered Deinonychus antirrhopus, a genus of carnivorous dromaeosaurid dinosaur that lived during the early Cretaceous Period in what is now the Western US.
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