In the innominate bones of a young child the box-shape exists, while its prominent abdomen resembles that of the gorilla.
"Scientific American Supplement, No. 447, July 26, 1884" by Various
The cup-shaped cavity of the innominate bone for receiving the head of the femur.
"A Practical Physiology" by Albert F. Blaisdell
Innominate bones and sacrum, ventral aspect.
"The Cambridge Natural History, Vol X., Mammalia" by Frank Evers Beddard
Now that the ribs are attached to the vertebrae, and the innominate bones to the sacrum, proceed to string the vertebrae again on the wires and rod.
"Taxidermy and Zoological Collecting" by William T. Hornaday