Some really solid work here! My only critique is the top-right pelvis - given that the horizontal, wide axis of the pelvis is heavily forshortened at this angle, I think you drew the bucket a little too wide and skinny. I have attached an image of a pelvis in a similar position and you can see it is less wide than what you have depicted. I also believe the back side of the illium in the same drawing is a bit too flate and you could have shown some more curvature. One final nitpick - the illiac crest is thicker than what you show in some of your drawings; I would show some more of a top plane.

Hey there! The proportions and anatomy seem pretty well done to me. I think you could make the spine thicker, currently they look a lot thinner than what stan tends to do. I also think the head in the bottom left drawing is a bit sketchy - in the original photo it appears more vertically angled. The connection between the skull and spine is a bit off too; your guiding lines make the spine look ovular and flat, and the angle of attachment is a bit extreme -- if you look at a reference, the spine tends to curve into the skull..