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

R. BOLMARO; M. AVALOS; P. RISSO; V. TARTALINI

La Falda, Córdoba

Congreso; 5to Congreso Argentino de Microscopía SAMIC; 2018

SAMIC

Reptiles are one of the largest classes among Tetrapods from the sub-phylumVertebrata. They share with birds the common trait of being born through eggs. Calciteand aragonite are the two most important and abundant crystalline forms ofCaCO3. Calcite is one of the most abundant minerals in the earth crust.Aragonite, despite being unstable at surface conditions of pressure andtemperature, is also present in large mineral deposits. They are the mainconstituents of mollusk shell bio minerals, either as sole component orcombined with each other. In eggs, of avian or reptilian origin, calcite isabsolutely dominant. Only some species of land turtles are known being composedof aragonite. This clear distinction attracted attention and drove us tocharacterize turtle, birds and yacare eggs in search for microstructuralcharacteristics and correlation between them.The studies were performed by scanning turtle eggs of Chelonoidischilensis, Phrynops hilairii and common chickens. Also X ray pole figures weremeasure by the reflection Schultz method. The structures were quite distinctive for turtles, resulting in afour layered calcite-aragonite composite material, which probably highlyenhance mechanical properties. Resultant textures are correlated with avian andother reptilian egg results, form the literature and the other speciescharacterized in the current work.