Study by XRD and EBSD of texture and microstructure of the eggs of several reptiles: Turtles, Caimans and modern birds

RISSO, PABLO; ÁVALOS, MARTINA; ÁVALOS, MARTINA; BOLMARO, RAÚL; TARTALINI, VANINA; BOLMARO, RAÚL; TARTALINI, VANINA; RISSO, PABLO

La Falda

Congreso; 5º Congreso Argentino de Microscopía; 2018

Reptiles are one of the largest classes among Tetrapods from the sub-phylum Vertebrata. They share with birds the common trait of being born through eggs. Calcite and aragonite are the two most important and abundant crystalline forms of CaCO3. Calcite is one of the most abundantminerals in the earth crust. Aragonite, despite being unstable at surface conditions of pressure and temperature, is also present in large mineral deposits. They are the main constituents of mollusk shell bio minerals, either as sole component or combined with each other. In eggs, of avian orreptilian origin, calcite is absolutely dominant. Only some species of land turtles are known being composed of aragonite. This clear distinction attracted attention and drove us to characterize turtle, birds and yacare eggs in search for microstructural characteristics and correlation betweenthem.The studies were performed by scanning turtle eggs of Chelonoidis chilensis, Phrynops hilairii and common chickens. Also X ray pole figures were measure by the reflection Schultz method.The structures were quite distinctive for turtles, resulting in a four layered calcite-aragonite composite material, which probably highly enhance mechanical properties. Resultant textures are correlated with avian and other reptilian egg results, form the literature and the other species characterized in the current work.