Effects of Sutured Pelvic Elements on Turtle Shell Strength: A Comparison of Pleurodire and Cryptodire Shell Mechanics

Abstract The two extant clades of turtles, Pleurodira and Cryptodira, can be distinguished by the fact that the pelvic elements of pleurodire turtles are extensively sutured to both the carapace and plastron whereas the pelvic elements of cryptodire turtles are not. Pleurodire shells are also generally flatter than those of cryptodires. These distinctive features could potentially contribute to differences in the strength of the shell in these two clades, but quantitative assessments are lacking. We asked the following questions: How do the sutured pelvic elements of Pelomedusa subrufa (Pleurodira) affect the strength of the turtle's shell? Does the height of the turtle shell affect shell strength? Are there differences in the strength of the shells of pleurodires and cryptodires living in the same geographic regions? We developed finite element models of pleurodire and cryptodire shells and used them to assess the effects of various morphologies and loading regimes on shell stress. The pleurodire model w...