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ABSTRACT Many species of lizards are partially enveloped by a dermal armour made of ossified units called osteoderms. Lizard osteoderms demonstrate considerable species-specific variation in morphology and histology. Although a physical/protective role (against predators, prey, conspecifics and impact loading during falls) is frequently advanced, empirical data on the biomechanics of lizard osteoderms are scarce, limiting our understanding of form–function relationships. Here, we report deformation recorded at the surface of temporal osteoderms during controlled external loading of preserved specimens of 11 lizard species (Tiliqua rugosa, Tiliqua scincoides, Corucia zebrata, Pseudopus apodus, Timon lepidus, Matobosaurus validus, Broadleysaurus major, Tribolonotus gracilis, Tribolonotus novaeguineae, Heloderma horridum and Heloderma suspectum). Based on the strain recorded in situ and from isolated osteoderms, the skin of the species investigated can be ranked along a marked stiffness gradient that mostly reflects the features of the osteoderms. Some species such as T. rugosa and the two Heloderma species had very stiff osteoderms and skin while others such as T. lepidus and P. apodus were at the other end of the spectrum. Histological sections of the osteoderms suggest that fused (versus compound) osteoderms with a thick layer of capping tissue are found in species with a stiff skin. In most cases, loading neighbouring osteoderms induced a large strain in the instrumented osteoderm, attesting that, in most species, lizard osteoderms are tightly interconnected. These data empirically confirm that the morphological diversity observed in lizard osteoderms is matched by variability in biomechanical properties. 

Additive manufacturing has been used to develop a variety of scaffold designs for clinical and industrial applications. Mechanical properties (i.e., compression, tension, bending, and torsion response) of these scaffolds are significantly important for load-bearing orthopaedic implants. In this study, we designed and additively manufactured porous metallic biomaterials based on two different types of triply periodic minimal surface structures (i.e., gyroid and diamond) that mimic the mechanical properties of bone, such as porosity, stiffness, and strength. Physical and mechanical properties, including compressive, tensile, bending, and torsional stiffness and strength of the developed scaffolds, were then characterised experimentally and numerically using finite element method. Sheet thickness was constant at 300 μm, and the unit cell size was varied to generate different pore sizes and porosities. Gyroid scaffolds had a pore size in the range of 600–1200 μm and a porosity in the range of 54–72%, respectively. Corresponding values for the diamond were 900–1500 μm and 56–70%. Both structure types were validated experimentally, and a wide range of mechanical properties (including stiffness and yield strength) were predicted using the finite element method. The stiffness and strength of both structures are comparable to that of cortical bone, hence reducing the risks of scaffold failure. The results demonstrate that the developed scaffolds mimic the physical and mechanical properties of cortical bone and can be suitable for bone replacement and orthopaedic implants. However, an optimal design should be chosen based on specific performance requirements.