Microstructure and microtexture characterization of avian eggshells

M. AVALOS; V. TARTALINI; P. RISSO; A. LOPEZ; M. HAUBER; J. REBOREDA; R. BOLMARO

St George Utah

Conferencia; 18th International Conference on Textures of Materials (ICOTOM-18); 2017

ICOTOM

The avian eggshell is the finalproduct of a calcium carbonate biomineralization process. As a result, itmainly consists of calcite crystals of different sizes and orientations.  Texture and microstructure are structural traitsthat influence the mechanical properties of the eggshell. These structuralcharacteristics are of particular interest for evolutionary interactions inavian brood parasitism behavior because thicker parasitic eggshells are moreresistant to punctures by hosts or conspecifics. In this work eggshell samples ofthree species of avian brood parasites (Icteridae:Molothrus) and seven hosts (Icteridae, Tyrannidae, Cardinalidae, Mimidae, Troglodytidae) were analyzed tocharacterize the microtexture and microstructure of the eggshell in order todocument variation between species.  Low vacuumElectron Backscatter Diffraction (EBSD) scans were performed in the eggshells ofthe selected avian species in the Radial-Tangential planes. We complementedthese scans with X ray pole figures from the same species? samples. The results show that together withcrystal size/thickness relationship, the networks ofgrain boundaries seem to be a microstructural characteristic to take intoaccount for understanding the resistance to puncturing. The analysis of EBSDresults indicated that the model of grain occupation was not sufficient toexplain the microstructure variation across different species? eggshells.