Fig. 3 in Carapace bone histology in the giant pleurodiran turtle Stupendemys geographicus: Phylogeny and function

Fig. 3. Bone histology of Stupendemys geographicus Wood, 1976. A, Sampled neural fragment (UNEFM−101) of Stupendemys geographicus Wood, 1976, late Miocene Urumaco Fm., Venezuela, South America. A1. Close−up of external cortex in normal transmitted light. The cortical bone is vascularized by primary and secondary osteons. Growth marks (small white arrows) occur throughout the external cortex. A2. Same external cortex as in A1, seen in polarized light. The external cortex constitutes a bone matrix of interwoven structural fiber bundles with scattered primary and secondary osteons. A. Close−up Ą 3