Fig. 2 in Carapace bone histology in the giant pleurodiran turtle Stupendemys geographicus: Phylogeny and function

Fig. 2. Selected photographs of the thin−sections used in this study in normal light. Cortical thicknesses are marked with a bracket. A. Neural of Stupendemys geographicus Wood, 1976 (UNEFM−101), late Miocene Urumaco Fm., Venezuela, South America. Internal and external cortices are of similar thickness. B. Costal fragment A of Stupendemys geographicus Wood, 1976 (UNEFM−CIAPP−2002−01; same provenance as in A). The plane of sectioning is perpendicular to the long−axis of the carapace (L−section). Both cortices are not clearly defined (signalized with question marks) due to diagenetic processes. C. Neural and costal (YPM 11853) of Podocnemis erythrocephala (Spix, 1824), Recent red−headed Amazon River turtle, South America (provenance unknown). Both cortices are of similar thickness. D. Costal (FM P27406) of Bothremys barberi (Schmidt, 1940), Campanian (Late Cretaceous) Mooreville Chalk, Selma Group, Dallas County, Alabama, USA. The internal cortex is reduced. E. Neural (YPM 40288) of Taphrosphys sulcatus (Leidy, 1856), Late Cretaceous, New Jersey, USA. The internal cortex is reduced. F. Plastral fragment (?hyo− or hypoplastron, IPB R559a) of "Foxemys cf. F. mechinorum", Late Cretaceous (early Maastrichtian), Cruzy, Hérault, southern France. The internal cortex is reduced. G. Drilled core of costal (MVZ 230517) of Pelomedusa subrufa (Bonnaterre, 1789), a Recent African helmeted turtle (provenance unknown). The keratinous shield still covers the bone. H. Xiphiplastron of Hesperotestudo (Caudochelys) crassiscutata (Leidy, 1889) (ROM 55400), Pleistocene, Florida, USA. Internal and external cortices that frame cancellous bone are of equal thickness. I. Shell element (YPM 1783) of Archelon ischyros Wieland, 1896, Late Cretaceous, South Dakota, USA. The bone tissue is uniformly cancellous. Abbreviations: CB, cancellous bone; ECO, external cortex; ICO, internal cortex; KS, keratinous shield. Scale bars 10 mm.