Tue Jan 23, 2007 2:38 pm
A biplane dinosaur?
Paleontologists have reassessed how a small, feathered dinosaur would have used its "biplane" wings to glide from treetop to treetop. Microraptor, the dinosaur, was discovered in China in 2003 but scientists recently reassessed how it would have flown, publishing their findings this week in the journal Proceedings of the National Academy of Sciences. At about 77cm in length, with a pigeon-sized body, Microraptor was a type of dinosaur known as a dromaeosaur and may be a relative of early birds. The dinosaur had two sets of feathered wings, on its forelimbs and hind legs and is believed to have "flown" like a flying squirrel - gliding, but incapable of true flight.
The Chinese scientists who found the Microraptor fossil proposed that when it glided between trees, it spread out its legs and kept its wings one behind the other in a tandem pattern similar to a dragonfly. But "We knew that there was something wrong anatomically. There is just one choice. It has to have this biplane wing design" said Sankar Chatterjee, paleontologist at Texas Tech University; using computer models and anatomical analysis, Chatterjee, and Jack Templin, an aeronautical engineer, decided that such an arrangement could not have worked. Chatterjee proposed that Microraptor positioned its hind legs below its body, adopting a "biplane" arrangement. A computer flight simulation of Microraptor employing this wing arrangement demonstrated it would undulate up and down, necessary for gliding among trees, and may have been able to glide over a distance of 40 metres.
It is widely believed among paleontologists that the first birds arose from small, feathered dinosaurs. Microraptor lived roughly 30 million years before the earliest-known bird, but Chatterjee said it may represent a throwback form that was an intermediate stage in bird evolution. The researchers also acknowledge this biplane design may have been a failed evolutionary experiment that did not lead to birds. Chatterjee said: "Basically what happened is there is a transition from biplane to monoplane. If you look at Archaeopteryx and all other (paleologically) true birds, they have this typical monoplane design." Pedopenna, another small dinosaur known only from partial remains, may also have used a biplane gliding arrangement, he said.
Other theories suggest birds evolved from little dinosaurs that were running and jumping from the ground, or that birds evolved from small dinosaurs living in trees that initially used feathers to control their descent like a parachute, before evolving a method of flight.
Chatterjee said the reassessment of Microraptor "settles once and for all that flight really evolved from trees down".
Which makes sense when you think about it. Animals that evolve to go up trees either develop climbing aids, such as claws, long limbs, prehensile tails etc, eg monkeys, sloths, or long necks to reach branches from the ground, as with giraffes and those long-necked mammals before the Ice Age.
I love it when these "missing-links" are found as they illustrate the evolutionary process quite elegantly, showing that Nature experiments before settling on workable solutions. I wonder what the catalyst was to evolve flight? thinningtree cover maybe die to climate change, forcing tree-dwelling species to adopt methods to move further afield in search of food and protection? it's been argued that this may a similar process may well have been at work forcing our arboreal ancestors to descend from the trees and walk on two legs (Swiss and Musk Rat being clear examples of reverse evolution, as they often are reduced to four limbed propulsion in order to crawl to the toilet bowl on a Friday night)
Edited by - Tawakalna on 1/23/2007 2:43:36 PM
The Chinese scientists who found the Microraptor fossil proposed that when it glided between trees, it spread out its legs and kept its wings one behind the other in a tandem pattern similar to a dragonfly. But "We knew that there was something wrong anatomically. There is just one choice. It has to have this biplane wing design" said Sankar Chatterjee, paleontologist at Texas Tech University; using computer models and anatomical analysis, Chatterjee, and Jack Templin, an aeronautical engineer, decided that such an arrangement could not have worked. Chatterjee proposed that Microraptor positioned its hind legs below its body, adopting a "biplane" arrangement. A computer flight simulation of Microraptor employing this wing arrangement demonstrated it would undulate up and down, necessary for gliding among trees, and may have been able to glide over a distance of 40 metres.
It is widely believed among paleontologists that the first birds arose from small, feathered dinosaurs. Microraptor lived roughly 30 million years before the earliest-known bird, but Chatterjee said it may represent a throwback form that was an intermediate stage in bird evolution. The researchers also acknowledge this biplane design may have been a failed evolutionary experiment that did not lead to birds. Chatterjee said: "Basically what happened is there is a transition from biplane to monoplane. If you look at Archaeopteryx and all other (paleologically) true birds, they have this typical monoplane design." Pedopenna, another small dinosaur known only from partial remains, may also have used a biplane gliding arrangement, he said.
Other theories suggest birds evolved from little dinosaurs that were running and jumping from the ground, or that birds evolved from small dinosaurs living in trees that initially used feathers to control their descent like a parachute, before evolving a method of flight.
Chatterjee said the reassessment of Microraptor "settles once and for all that flight really evolved from trees down".
Which makes sense when you think about it. Animals that evolve to go up trees either develop climbing aids, such as claws, long limbs, prehensile tails etc, eg monkeys, sloths, or long necks to reach branches from the ground, as with giraffes and those long-necked mammals before the Ice Age.
I love it when these "missing-links" are found as they illustrate the evolutionary process quite elegantly, showing that Nature experiments before settling on workable solutions. I wonder what the catalyst was to evolve flight? thinningtree cover maybe die to climate change, forcing tree-dwelling species to adopt methods to move further afield in search of food and protection? it's been argued that this may a similar process may well have been at work forcing our arboreal ancestors to descend from the trees and walk on two legs (Swiss and Musk Rat being clear examples of reverse evolution, as they often are reduced to four limbed propulsion in order to crawl to the toilet bowl on a Friday night)
Edited by - Tawakalna on 1/23/2007 2:43:36 PM