Possible Clues:

• Bone male bird number six reportedly found
• Reported bird found with half a dozen fused vertebrae
• Bone of bird — one following five others, do we hear?
• Terminal bone of the vertebral column
• Bone at the bottom of the spine
• Tip of the vertebral column
• Triangular bone at the base of the spine
• Bone
• Sacrum neighbor
• Bone at the spine’s base