What is unique about a hominid pelvis when compared to other primates

The hominid pelvis displays many unique features (when compared to

that of quadrupedal primates) that support bipedalism. The major

adaptations are seen in the sacrum and the ilia, as well as in the

overall configuration and orientation of the pelvic bones.

Explanation:

These changes in the sacrum were for the adaption of standing on two legs,

The uniqueness is also that ilia are rotated and curved medially, bringing the lateral edge of  the blade forward and projecting the top of the ilia outward laterally.

1. efficient use of space

2. elimination of groundwater contamination

3. energy generation

4. lower carbon footprint

not only is it colder, it also becomes darker, less salty, and more dense.