SACH-SAWCH

Dinosaurs that could easily catch you (even if you were on a 24 speed bicycle) came in two flavors. The original flavor was sling-like hips (hip socket not yet evolved). Over time improved neurology allowed beasts to give up some extreme hip swimming mobility from SLING-LIKE body/leg attachment. Cows, dogs, cats etc are four legged but only have hips in the hind legs. A bone-in-bone socket articulation FIXES the hip centers relative to the body. Early dinosaurs evolved hips because given these constraints their improving neural abilities could sense and alter muscular leg actions more quickly and with better control. Go faster? No. But nearly as fast with height modulation that kept body travel level & uniform in forward speed. ENERGY!! Less energy = less need for food = less hunting, more time between meals, can go longer without food to find new hunting places. Less was more. Do you want to increase your MOBILITY on the dance floor? Drop marbles. Hmm m. Front legs (no hips) actually detract. Predators wanting long runs go vertical off their front legs. Bigger arms need bigger tail = slower? Maybe? Maybe not. Anyway the point is that hip joints are not to allow walking or running. Humans without those (they are among you) can do both. They waddle. It just takes more energy. But with hips it is energy conserving tuned to maximum for walking but with variations that are allowed when there are other needs. The fine tuning of our control mechanism is sharpened by having neurological EXPECTATION . I offer this as another important determinant of gait. We walk much better over ground that is familiar to us. In unfamiliar circumstances we slow and dial in stability patterns for the uncertainties of movement to come. The need to just walk when the energy conservation tricks are thwarted calls upon next best choices (bigger wheel? Still centered below floor???).