Reverse Engineering of the Alligator Gar Fish's Boney Scale: The Confluence of Mineralogy-Biology-Engineering

Kenneth Livi, Johns Hopkins University

Alligator gar (Atractosteus spatula) is a modern armored fish thought to be descended from Mesozoic-age, ray-finned boney fish (palaeoniscoids). Its scales are dermal denticles consisting of a boney core and a ganoid enamel-like (ganoine) cap. Interest in the boney scales comes from a diversity of disciplines: from mechanical engineers who are interested in its mechanical properties, like its delamination toughness; from geologists and mineralogists who are interested in biomineralization and isotope analyses of fossil gars; and biologists who are interested in its bone structure. Several characterization techniques were employed to reverse engineer the gar scale from millimeter-scale porosity down to individual hydroxyapatite platelets. This comprehensive data set is a basis for ongoing computer modeling of the physical properties of the scale and improved conceptual models for the hierarchical structure of bone.