Fig. 3.
Thin section micrographs of dinosaur bones. The scale bar is 100 μm in all micrographs. (A) Overview of the Haversian dinosaur bone with mineral infillings in bone pore space and diagenetic cracks. All Haversian canals are completely or partially filled with diagenetic pyrolusite (MnO2). Some infillings have spirit levels. (B) Osteon with osteocyte lacunae and canaliculi filled with pyrolusite. The pyrolusite-filled Haversian canal in the centre has a frayed-looking margin due to etching during manganese precipitation. (C) Haversian canal half filled with pyrolusite, forming a spirit level. Chalcedony fills the space above the pyrolusite. Polarized light shows the fine needle-like crystals, which are characteristic for chalcedony. (D) Haversian canal with two level planes of pyrolusite infills (arrows), indicating the bone rotated during precipitation of the pyrolusite. (E) Central cracks from the Haversian canal filled with pyrolusite. (F) Peripheral cracks extending inwards from the circumference of a secondary osteon.