The pelvis and rib cage form a supportive connection
In Flamenco posture, the pelvis is the base of the torso. A useful starting position lies between two extremes: a pronounced forward tilt, which creates a noticeable arch in the lower back, and a strong tuck, where you squeeze your buttocks. The right pelvic position for you is not a millimeter-perfect template. Body types and natural spinal curves vary.
The rib cage is supported above it. Thinking of aligning the pelvis and rib cage one above the other helps prevent your ribs from pushing forward unintentionally. This does not mean keeping your spine geometrically straight. Good posture preserves the natural curves of your back instead of forcibly flattening them. You create length without pushing your belly forward or your shoulders back.
Your breastbone can lift. What matters is whether you push your whole rib cage forward or gently lengthen the front of your body. Your lowest ribs do not need to be visibly drawn in. They simply should not constantly flare out to create the illusion of a bigger pose.
This relationship between the different parts of the body is part of basic Flamenco technique. Here, the focus is on the torso, not the mechanics of footwork or shifting your weight.

