Zonneveld et al.—Bored turtle shell 1 (dorsal) surface
internal surface
visceral surface
internal surface
internal surface
rP1 plastron external (ventral) surface
23 nuchal
rP2 rP3 rP4
peripherals lP3
costals lP4 lC2 lP5 lC3
lP6 lP7 lP8
lP9 lP10 lP11 lP12 rP9 rP10 rP11 rP12 pygal
Figure 3. Summary of osteological terminology used in the South Pass vertebrate boring study. (1) Cross-section through a generalized emydid turtle showing the surfaces of bones. ‘Visceral surface’ denotes bone surfaces that would have been covered by animal’s soft tissue during life. ‘Dorsal surface,’‘ventral surface,’ ‘external surface,’ and ‘internal surface’ denote surfaces of the bone that were covered in a thin layer of epidural scute and were prone to parasite colonization during the animal’s life span. (2) Identification of carapace elements including, at top and base, those portions of the carapace not covered by viscera. ‘l’ and ‘r’ denote left and right, respectively. (3)Identification of plastron elements including, at top and base, those portions of the plastron not covered by viscera.