Answer:
Thoracic cage and vertebral column.
Explanation:
The bones of the head and the bones that make up the trunk of a vertebrate organism form the <em>axial skeleton. </em>
In the case of humans the axial skeleton consists of a total of 80 bones which are broadly organized into 6 parts:
1. Bones of the skull
2. Middle ear ossicles
3. Hyoid bone
4. Thoracic/rib cage
5. sternum
6. Vertebral column
When they are capable of interbreeding to produce a viable/ fertile off-springs.
I'm pretty sure it's high density as a solid.
