(Xu, Zhou, Wang, Kuang, and Du, 2003)

In early Cretaceous China, feathered, and even winged dinosaurs are relatively common place. Beipiaosaurs lumber through the forest bearing coats of downy fuzz, Caudipteryx have display feathers on forelimbs and tail, and, of course, birds like Confuciusornis are fully capable of flight.   Even the hitherto unheard of climbing dinosaurs are represented in this time and place, by such creatures as Scansoriopteryx.  One arboreal dinosaur, Microraptor zhaoianus, even leaps from branch to branch like a monkey, using feathers on its arms, legs, and tail to control its falls.  With all these strange a wonderful variations on the dinosaur/bird theme, it is easy to think that early Cretaceous Asia has exhausted its store of surprises.  This is not the case, however.

Microraptor gui  is a deinonychosaur, a distant relative of Velociraptor, part of a group of dinosaurs usually thought of as ground-running predators. Some, however, like M. gui's close relative M. zhaoianus, are climbers, and these forms show many bird-like attributes, even compared to others in this very bird-like group.  Like M. zhaoianus, M. gui is a climber, but this species takes the tree-jumping behavior much farther. 

M. gui sports true flight feathers, not only on its arms, as in birds, but on its legs as well, making it the only known vertebrate with two pairs of wings.  The fore-wings are long and curved, like the wings of a flying bird, and, powered by muscles attached to a plate-shaped sternum, they are capable of flapping, though not as powerfully as those of a true bird.  The hind-wings, by comparison, are broad, and, because of the limitations of dinosaurian hip-joints, rather immobile.  The hind-wings do not flap, but instead provide stability in the air, while the fore-wings provide steering and some thrust, making this M gui and extremely versatile little predator.

Whether or no M. gui can actually fly, or whether its locomotion can only be called very efficient gliding is still a subject of debate.  No other four-winged vertebrates are known, and so there are few reference points to guide those who study this dinosaur (comparisons to human-built bi-planes seem to be the best analogy).  Whatever the final verdict, the four-winged design seems to at least have been successful in at least this one case. 

Other sites containing pertinent information:

The Dinosauricon's Microraptor page (Great pictures!)

Dinodata's M. gui

Megaraptor's discussion of M. gui

Raptoriffic's M. gui picture

Sinofossa's Microraptor

Boban Filipovic's M. gui models (1) and (2)

© Daniel Bensen 2004
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