oa Molecular Preservation of Bone Marrow in a Cetacean Humerus (NYE Formation, Miocene, U.S.A.)

Yellow bone marrow (a type of fat tissue) is conserved across most vertebrate lineages. Red bone marrow, however, is the centre of blood production used by vertebrates that descended from terrestrial lineages. The innovation of red bone marrow must have occurred at a time during, or shortly after, the deviation of tetrapods from other vertebrates.

The methods employed in this study aim to complement previous research on the internal microanatomical structure of fossil bones. A comprehensive organic and inorganic analysis of a Miocene cetacean humerus revealed remarkable molecular distinction between the fossil trabecular network and the surrounding carbonate concretion. A striking abundance of very early diagenetic cholesteroids coupled with programmed pyrolysis data and other molecular proxies provide insights into the conditions inside bone marrow microenvironments during fossilisation.