Figure 2 in Turtle shell bone and osteoderm histology of Mesozoic and Cenozoic stem-trionychian Adocidae and Nanhsiungchelyidae (Cryptodira: Adocusia) from Central Asia, Mongolia, and North America

Figure 2. Bone histology of Adocidae from Central Asia and Mongolia. Images (a), (c), and (e) are in normal transmitted light, images (b), (d), and (f) in polarised light. (a) Close-up of the external cortex of ZIN PH 84/87 ("Ferganemys" itemirensis). Growth marks are visible in the more external zone, whereas the more internal zone is dominated by an extensive reticular vascularisation pattern. (b) Close-up of the external cortex of ZIN PH 2/116 (Shachemys sp., xiphiplastron: external bone surface is in lower part of image). The more external zone shows highly birefringent growth marks, whereas the more internal zone is increasingly remodelled by secondary osteons. (c) Close-up of the external cortex of ZIN PH 92 (Adocus dzhurtasensis). Note absence of the more external zone. (d) Interior coarse cancellous bone of ZIN PH 593/64 (Adocus foveatus). (e) Close-up of the interior trabecular bone of ZIN PH 2/91 (Adocus sp.). (f) Close-up of the internal cortex of ZIN PH 37/86 ("Ferganemys" itermirensis, plastron fragment) showing parallel-fibred bone grading into lamellar bone. Note the light and dark extinction pattern of the tissue. Abbreviations: EC, erosion cavities; GM, growth mark; ISF, interwoven structural fibre bundles; PFBLZB, parallel-fibred bone-lamellar zonal bone; PC, primary vascular canal; RVP, reticular vascularisation pattern; SO, secondary osteon; TR, trabecular bone.