primitive bone
primordial bone

They resemble primitive bone marrow in hagfish.

The drawback of both these performances lay perhaps in the dignity of their conductor, a man with not a lurid or a primitive bone in his body.

The lower jaw of reptiles has only a single coronoid and splenial, but retains all the other primitive bones except the prearticular and the periosteum.

Dr. Zsebo's group has produced stem cell factor, a substance that stimulates very primitive bone marrow cells to grow and develop into red and white blood cells.

However, the vast majority of later vertebrates, including modern amphibians, have undergone varying degrees of loss and fusion of these primitive bones, resulting in a smaller number of carpals.

Unclothed by forest, the primordial bone of the Great Mother lay exposed in the tilted landscape.