Bone marrow Bone marrow Bone marrow is a semi-solid tissue which may be found within the spongy or cancellous portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production or hematopoiesis. It is composed of hematopoietic cells, marrow adipose tissue, and supportive stromal cells. In adult humans, bone marrow is primarily located in the ribs, vertebrae, sternum, and bones of the pelvis. On average, bone marrow constitutes 4% of the total body mass of humans; in an adult having 65 kilograms of mass (143 lb), bone marrow typically accounts for approximately . Human marrow
Sacrum bone of Tequixquiac Sacrum bone of Tequixquiac The Sacrum bone of Tequixquiac is an ancient paleo-Indian sculpture carved in a pleistocene-era bone of a prehistoric camel. It was found by Mexican naturalist Mariano Bárcena in 1870. It is considered among the earliest pieces of art from the American continent. A sacrum bone found in Tequixquiac is considered a work of prehistoric art. These people were nomadic, hunting large animals such as mammoths and gathering fruits as evidenced by archaeological evidence found at the site. One of the most salient discoveries of primitive art in America was found here, called the Sacrum bone of