Fig. 5 in Carapace bone histology in the giant pleurodiran turtle Stupendemys geographicus: Phylogeny and function

Fig. 5. Bone histology of the bothremydid turtles Bothremys barberi (Schmidt, 1940) and Taphrosphys sulcatus (Leidy, 1856). A. Sampled costal (FM P27406) of Bothremys barberi (Schmidt, 1940), Campanian (Late Cretaceous) Mooreville Chalk, Selma Group, Dallas County, Alabama, USA. A1. External cortex observed in normal light. Widely spaced growth marks are found in this detail of the cortex. The bone tissue in between the growth marks is vascularized by primary osteons or branching primary canals. Structural fiber bundles that trend perpendicular to the surface of the bone are found throughout the whole of the cortex. A2. Same view as in A1, seen in polarized light. Perpendicular fiber bundles cross the interwoven structural fiber bundles. Note that not all growth marks (small white arrows) appear as bright, birefringent lines in the fibrous tissue. B. Sampled neural (YPM 40288) of Taphrosphys sulcatus (Leidy, 1856), Late Cretaceous, New Jersey, USA. B1. External cortex and external part of cancellous bone are observed in normal light. The cortical bone has 20 growth marks (small white arrows). Vascularization is accomplished through primary osteons and primary canals. Ą