SOFT TISSUES, HARD BONES - THE BACTERIA CONNECTION

The discovery of soft pliable tissues and micron-size iron-oxygen spheres in Tyrannosaur bone could potentially be one of the most important discoveries in paleontology. Continuing research by Schweitzer et. al. shows certain signs of biomolecules but positive identification of these structures remains elusive. The current work resulted from a scanning electron microscope (SEM) survey of fossil bone across time and taxa, surprisingly revealing large numbers of these structures. The hypothesis put forth here is that some of these structures are secondary and hosted by the bones. They resulted from two sources, the microbial infiltration of the hollow voids and transformation of the primary pyrite framboids. Bacteria produce extracellular polymeric substances (EPS) commonly known as “slime” on virtually any water/surface boundary. The extracellular component of these biofilms harbor ionic bonds that attract dissolved minerals, which eventually harden the biofilm. Here we suggest that early stage biofilm infiltration, prior to mineralization, results in soft pliable structures remaining after acid digestion of fossil bone. The biofilms morphology matches the open voids in the fossil bone such as vascular structures and osteocytes. Once mineralized, they can be identified by the irregular structure of the mineralized film, which will be shown through SEM and energy dispersive spectroscopy. The iron-oxygen spheres are identified as a sub-category of framboids often associated with biological activity but known to be inorganic in their formation. Bacterial decomposition often produces sulfur, which combines with iron, to form the framboid sphere. Over time, under oxidizing conditions, a pyrite framboid may oxidize into iron oxide while preserving the original texture, thus resulting in the eventual elemental iron-oxygen signature. Infrared spectroscopy was used to compare modern biofilms, modern collagen and fossil bone coatings. An initial correlation of the infrared spectrums indicate that the fossil specimens show a closer match to modern biofilms than to modern collagen.