Virtual repair of fossil CT scan data

X-ray micro-tomography (XMT) and 3D image-based modelling software hasunlocked the ability to digitally repair distorted or broken fossil specimens, thus permitting interpretation of previously unusable finds in finite element analyses (FEA). A fossilized terminal ungual phalanx from the manus of the dromaeosaurVelociraptor mongoliensis (Manchester Museum, University of Manchester, specimen LL.12392) was scanned at the Henry Moseley X-ray Imaging Facility.Inspection of radiographs revealed the Velociraptor manual ungual was broken inseveral places, previously going unnoticed due to cement repair of the fossil. Afterconducting a high resolution scan of the ungual the increased sensitivity of the apparatus enabled separation of areas of differing density, in this case the fossilized bone and cement. Image-based modelling software produced by Simpleware (Simpleware Ltd, Rennes Drive, Exeter, EX4 4RN, UK.) allowed slice-by-slice repair in three planes, resulting in a complete, fully stitched 3D digital model of the ungual, whilst maintaining internal cavities and the micron resolution reconstruction of trabecular bone architecture. This software also has the capability to digitally re-inflate specimens that have been compressed during fossilization, restoring skeletons to their original shape and dimension. 3D dissections on geometrically precise reconstructions allow the interpretation of previously unusable specimens and reinterpretation of already described fossils. Further, use of Simpleware software to convert repaired fossils into microstructurally-faithful finite element meshes enable the biomechanicaltesting of these repaired structures. Testing of fossil structure and function isalready underway at the University of Manchester and is adding to our knowledgeof the mechanical behaviour of extinct animal biomaterials.