Reconstructing hypothetical sauropod tails by means of 3D digitizationLirainosaurus astibiae as case study

Resumen

Purpose Dinosaur fossil skeletons are rarely found complete and from a single individual. Most findings include remains from several individuals of different sizes and ontogenetic stages. Although many skeletal models have been produced from various specimens, such as 2D drawings, physical mounts or 3D virtual models, the detailed techniques employed in their crafting have not been always published. Our main goal is to describe a thorough methodology to elaborate a 3D reconstruction of a caudal vertebral series from different sized specimens and discuss the main caveats. Methods Here we propose a hypothetical reconstruction of the tail of the titanosaurian sauropod Lirainosaurus astibiae to assess its neutral posture and range of motion thanks to a virtual 3D skeletal mount. We use 3D models obtained by photogrammetry of the vertebrae. 3D specimens allow an easy access, study and visualization of the specimens minimizing manipulation of fragile and/or heavy originals, greatly helping in their conservation. A step-by-step protocol on virtual retrodeformation for vertebral series and the criteria employed are devised. The retrodeformed 3D models are articulated and analyzed on CAD (Computer Aided Design) software, allowing an accurate study of skeletal ranges of motion. Results The resulting virtual tail has a osteological neutral pose similar to other titanosaurs. Slightly different vertebral morphologies hint at a slight regionalization of the tail in terms of motion. Conclusions The proposed methodology will help reconstructing the incomplete or poorly preserved tails of other sauropod taxa, being a helpful tool to compare the biomechanics within this clade.