Allen and others, Nature, 2013.
Fig. 2: Reconstructed body volumes of dinosaur (left) and bird (right) based on digitized fossil skeletons and CT scans of modern relatives. These show the major changes in body proportions that evolved along the bird line.
News flash! Big bird’s got horrible posture . . . for a bird.
This is Sandra Tsing Loh with the Loh Down on Science, and on why birds have crouched body forms.
Birds may have two legs, but most don’t stand upright. They hop around in a permanently tucked position. Think: downhill skier with feathers. But why—when they evolved from dinosaurs that stood fairly erect? Over time, did their heavy tails shrink, making them top-heavy? And did their skeletons bend at the knees to offset the shift in balance?
Enter John Hutchinson from the University of London. He digitally reconstructed the bodies of the dinosaur ancestors of birds. How? Scan fossils into software. Add meat to the bones. Make the dinos move. He analyzed changes in body parts over time—and how these changes affected posture.
Surprising result? Tail shrinking didn’t appear to do squat! Rather, early birds’ tiny T. rex arms grew longer and thicker, and eventually into wings. Their heads and necks also got beefier. And this shifted their center of gravity forward. The rest is history.
And that's how Crouching Sparrow came from Hidden Dragon!
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