Insight into the evolution of bones: Modern biology considers bone cells (osteocytes) as essential for bone development and health – Science Daily

A joint team of palaeontologists has now for the first time analyzed bone structures in 400 million-year-old fossils of marine life at unprecedentedly high resolution and in 3D. To be able to view these structures, tomography experts examined the samples under the focused ion beam of a scanning electron microscope to calculate 3D images from the data, achieving resolutions in the nanometer range using technology that was initially developed to study battery corrosion.

Whether fish, fowl, or mammal, all vertebrates have an internal skeleton of bones. In almost all vertebrates (with the exception of certain bony fish), the bone consists of a complex composite of minerals, proteins, and living bone cells (osteocytes) entrapped in the bone matrix. The bone cells are interconnected by tiny channels so that they can exchange substances and electrochemical signals, allowing the bone to grow and regenerate. Still, this complex architecture of live and inorganic material must have emerged at some point in the course of evolution. A team at the Museum für Naturkunde Berlin headed by Dr Florian Witzmann is investigating how and when this happened. Now they have discovered a possible milestone in this development.

They have examined fossilised samples of bony armour from two early fish species that lived around 400 million years ago. One sample came from Tremataspis mammillata, a jawless fish that lived in the late Silurian period about 423 million years ago and belongs to the extinct group called Osteostraci. The second, much younger sample was a