The medullary cavity is the central cavity of bone shafts where red bone marrow and/or yellow bone marrow is stored; hence, the medullary cavity is also known as the marrow cavity.
Comparative anatomy
This area is involved in the formation of red blood cells and white blood cells, In some dinosaurs, reptiles, and birds, a medullary bone grows here, which supplies the calcium supply for eggshells. This has been detected in fossil bones despite the fossilization process. It is not found in crocodiles or reptiles. ==References==