¡Viva la Science! When tiny arms became crooked legs Big Bird is
a terrible example to us all, at least when it comes to bird
anatomy. Check out those gams and you’ll see why. Like humans,
real birds are bipedal, but their legs aren’t straight up and
down. Instead, bird legs zigzag in such a way that birds are
essentially in a permanent crouch, using their muscles to resist
gravity. We humans don’t have to do that―our weight is borne
passively on our straighter frames. But of course, we can’t fly.
The crouching posture peculiar to birds, says a recent study
published in Nature, has everything to do with their evolution
from dinosaur ancestors into animals capable of flight.
Previously, it was believed that the bird stance came about as a
way for bird bodies to balance as massive T-Rex-style tails
disappeared. Using 3-D digital reconstruction, however, the
authors of the study determined that the key change was actually
in the size of those adorable dinosaur arms. According to co-
author John R. Hutchinson: The