Reanalysis of 4-Winged Dinosaur May Illuminate Evolution of Bird Flight

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How did the ancestors of birds evolve the ability to fly? That birds are descended from small, meat-eating dinosaurs is established. Exactly how the creatures conquered the air remains a mystery, however. Now the authors of a new study of a controversial feathered dinosaur say they have resolved a key aspect of the problem—namely, how the animals controlled their flight once they became airborne.


Two theories have dominated the long-running debate over how bird flight evolved. In the so-called cursorial scenario, the ability to fly emerged in terrestrial dinosaurs that raced across the ground with their arms outstretched and leaped into the air after prey or out of harm’s way, their wing feathers providing lift. The arboreal scenario, in contrast, supposes that flight arose in tree-dwelling dinosaurs that were built for gliding and started flapping their arms in order to stay aloft longer.

In 2003 a feathered dinosaur fossil came to light that was purported to elucidate the question of how flight evolved. The roughly 125-million-year-old specimen exhibited evidence of feathers on its hind limbs in addition to its forelimbs, prompting researchers to describe the crow-size animal,Microraptor guias a four-winged dinosaur. A startling artist’s reconstruction accompanied the description of the fossil remains, showing the bird flying with its hindlimbs spread out to the side, as if doing a split. The authors argued that the feathered hindlimbs, together with the forelimb wings, acted as an airfoil to help the animal glide. Critics begged to differ.

Written By: Kate Wong 
continue to source article at blogs.scientificamerican.com

4 COMMENTS

  1. Regardless of the specific physiological aspects of the dinosaur, the process of evolution happening then and leading to the life forms we see and are today is astounding, yet logical. Visiting a dinosaur museum was an awakening for my wife and children from a  very Catholic country. To actually see proof of evolution and even the physiological similarities of the creatures of the past to even modern humans really opened their minds.

  2. @OP:disqus
      – The authors argued that the feathered hindlimbs, together with the forelimb wings, acted as an airfoil to help the animal glide.

    Interestingly, we were looking at the use of hind fins as aids to flight on the  Flying Fish discussion.
    http://richarddawkins.net/news

    There was also a discussion of feather evolution and flight on the old RD site here:- http://old.richarddawkins.net/

    .. and a late comment on it from me + a link on the evolved “feathers” of the Cactus Mam. plumosa here:- http://old.richarddawkins.net/

  3. Two things come to mind.  One is whether selection for altering the feathers of the fore-limbs for gliding or for flight just happened to drag the hind limbs feathers along with them because there wasn’t a differentiation going on with those particular changes.  The other is that the hind limb feathers may not have been selected for function, the most obvious alternative being sexual selection which we have seen can produce a wide array of otherwise useless or even detrimental feathered structures.

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