n.the bodily attribute of being bipedal; having two feet

"bipedalism made the human form of birth possible"

Bipedalism.
Bipedalism
Bipedalism
Bipedalism, flight, and the evolution of theropod locomotor diversity
Origin of human bipedalism: The knuckle-walking hypothesis revisited
Bioenergetics and the origin of hominid bipedalism
Origin of human bipedalism as an adaptation for locomotion on flexible branches.
Chimpanzee locomotor energetics and the origin of human bipedalism
Insights into the evolution of human bipedalism from experimental studies of humans and other primates
Orrorin Tugenensis Femoral Morphology and the Evolution of Hominin Bipedalism
Taylor & Francis Online :: Bipedalism, flight, and the evolution of theropod locomotor diversity - Journal of Vertebrate Paleontolog...
Climbing, brachiation, and terrestrial quadrupedalism: Historical precursors of hominid bipedalism
Reasons why mammalian bipedalism is so rare. Problems encountered by the larger arboreal mammals when they descend to ground level...