Sacrum lumbar vertebra, and its lower part with the coccyx (tailbone) via the sacral and coccygeal cornua. The sacrum has three different surfaces which are shaped to accommodate surrounding pelvic structures. Overall it is concave (curved upon itself). The base of the sacrum, the broadest and uppermost part, is tilted forward as the sacral promontory internally. The central part is curved outward toward the posterior, allowing greater room for the pelvic cavity. In all other quadrupedal vertebrates, the pelvic vertebrae undergo a similar developmental process to form a sacrum in the adult, even while the bony tail (caudal) vertebrae remain unfused.
The White Bone the novel are mostly from the "She-S" family, into which Mud, a young cow who is pregnant with her first calf, has been adopted. Mud is blessed with visionary powers and can occasionally see into the future. Thrown into a drought, with human poachers becoming increasingly common, Mud and her family must find the legendary "Safe Place" where drought and poachers do not come. The "White Bone," a rib of a newborn elephant, is rumored to be lying somewhere in the savannah and is said to point in the direction of the Safe Place. After a slaughter which leaves most