A fossilised Microraptor qui. The inset shows the outline of the flight feathers on the dinosaur's hind limbs.
Credit: PNAS
CANBERRA: The origin of powered flight in modern birds was in biplane-like dinosaurs living in trees 125 million years ago, according to a new U.S. and Canadian study.
"The origin of avian flight has been debated for a century," said co-author Sankar Charterjee from Texas Tech University, in Lubbock, USA. His team claim to have finally settled the long-standing debate, discovering that powered flight developed from dinosaurs that glided down from trees, rather than taking off from the ground.
The team, who reported their results today in the U.S. journal, Proceedings of the National Academy of Sciences, studied fossils of the feathered dinosaur Microraptor gui, which lived 125 million years ago in the early Cretaceous period in northeastern China. Microraptor was around 77 cm long, including its tail, and weighed about 1 kg.
When Microraptor skeletons were first discovered in 2003, scientists were surprised to find that they had not one set of wings, but two. In addition to the 'standard' wings on the animals' forelimbs, Microraptor's feet and legs sported flight feathers as well. At the time, scientists thought two sets of wings sat behind one another in tandem, a bit like a modern-day bat.
But Charterjee, and his Canadian colleague R. Jack Templin, realised that the wings were actually positioned with one set of wings above the other, like early biplanes.
The team realised that this wing configuration could not provide a Microraptor with powered flight; the dinosaurs would have been capable only of gliding. More importantly, the dinosaur had no way of lifting their wings up, so during a ground-based take-off the wings would have been damaged.
By analysing the dinosaur's aerodynamics, the researchers calculated that Microraptor could have travelled more than 40 metres with a small jump from a tall tree. It would have fallen quickly to begin with, but then could have swooped back up to land on the branch of another tree.
According to the researchers, "this mode of transportation would have been energetically very efficient for Microraptor." Gliding between trees doesn't require much energy because it is assisted by gravity, they said.
Further analysis of the feathers and wings showed that the Microraptor could not have landed on the ground after jumping from a tree. The wings were not capable of acting like a parachute, and they would have crashed into the ground at up to 8.7 metres per second - enough to cause serious injury.
According to the study, this four-winged gliding system could have occurred on the evolutionary tree in one of two places. Either it was an evolutionary experiment in one group of dinosaurs that eventually failed, or avian flight went through a four-winged stage before losing one of the sets of wings.
Fossil evidence supports the latter view, according to the researchers, because the skeletons of six other dinosaurs that lived from 140 million to 125 million years ago show a gradual shift from wings on both hind and forelimbs toward wings only on the forelimbs.
is this the onion? you ARE
is this the onion?
you ARE kidding,right?
response to first comment
Go home, you stupid creationist.
Re: response to first comment
Science for the win.
Bird wings evolved from biplane dinosaurs
I think that the statement that "Bird wings evolving from biplane dinosaurs" is an incorrect perception therefore pre-empting the wrong conclusions from this apparent mistaken concept. When the microraptor leapt from a take-off position, it withdrew its legs back to form an efficient stabilizing tail and manoeuvrability, to assist with lift in the rear end of it's body, moving the centre of gravity forward, so the forward wings provided the lift to a more balanced payload of its body. This also avoided drag like the modern day birds withdrawing their legs upon "take off". This instinct could have easily developed and evolved through the ages to the modern day, when birds withdraw their legs back to avoid drag thus fanning out their tails in one movement. If you agree with this concept, it therefore leads onto my theory or idea on how powered flight developed the sternum and muscles, evolving to the present day species of birds, which in my mind, joins seamlessly onto my above theory-concept! If you are interested in hearing-reading the second half of my conclusions, please let me know here at this site and it would be my pleasure to do so!