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Tuesday, February 16, 2010
Did dinosaurs evolve from birds or birds from dinos?
Study questions current evolutionary beliefs about birds
Latest study published in the Proceedings of the National Academy of Sciences proposes that Dinosaurs might actually have evolved from birds and not the other way around, as is commonly believed.
Oregon State University zoology professor John Ruben presents commentary about the study, which tested a latest specimen of raptor fossil discovered in 2003. The PNAS study reveled that the “small, feathered species must have been a ‘glider’ that came down from trees.”
The general and long-held belief that raptors and other ground-dwelling dinosaurs ultimately became birds is brought into question by the research, which Ruben says presents sound evidence that birds eventually became certain types of dinosaurs. For instance, the velociraptor so prominent in Jurassic Park might really have been a flightless bird.
Analysis of the feathers on the “microraptor’s” four limbs implies that the dinosaur probably couldn’t have taken off for ground-up flight, but were probably gliding from trees, “somewhat like a modern-day flying squirrel.” Ruben says this analysis builds it improbable that dinosaurs one day took to the skies but, rather, that birds one day touched down and stayed put, finally becoming dinosaurs.
Labels: Dinosaur animals, Dinosaur reptile, Dinosaurs, Extinction of Dinosaurs, First dinosaur
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Monday, December 14, 2009
Bones show early divergence of dinosaur lineage
The early evolution of dinosaurs, in the late Triassic period, is fuzzy, to say the least.
Paleontologists recognize that the first dinosaurs emerge about 230 million years ago, but fossil evidence is so spotty that it is unapparent where and when the major lineages — theropods, sauropods and ornithischians — began to diverge.
Some excellent 215-million-year-old fossils unearthed in Ghost Ranch, in northern New Mexico, are aiding to clarify things. The bones, of a theropod that the discoverers have named Tawa hallae, offer strong support for the idea that the major lineages diverged early in dinosaur evolution in the part of the supercontinent Pangea that is now South America.
“What Tawa does is it helps intimate the relationships at the base of dinosauria,” said Sterling J. Nesbitt, a postdoctoral researcher at the University of Texas and lead author of a paper in Science describing the find.
Labels: Dinosaurs, Dinosaurs images, Extinction of Dinosaurs, First dinosaur
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