Virtual repair of fossil CT scan data

X-ray micro-computed tomography (micro-CT) and 3D image-based modeling software has unlocked the ability to digitally repair distorted or broken fossil specimens, thus opening the way for interpretation of previously unusable finds. A fossilized terminal ungual phalanx from the manus of the dromaeosaur Velociraptor mongoliensis (Manchester Museum, University of Manchester, specimen LL.12392) was micro-CT scanned at the Henry Moseley X-ray Imaging Facility. Inspection of low-resolution fast-scans, revealed the Velociraptor manual ungual specimen was broken in several places, previously going unnoticed due to cement repair of the fossil. After conducting a longer high-resolution scan of the ungual the high sensitivity of the apparatus enabled separation of areas of differing density, in this case the fossilized bone and cement. Image-based modeling software produced by Simpleware allowed slice-by-slice repair in 3 planes, resulting in a complete, fully stitched 3D digital model of the ungual, whilst maintaining internal cavities and the micrometer reconstruction of trabecular architecture. This software also has the potential capability to reinflate specimens that have been compressed during fossilization, restoring skeletons to their true shape and dimension as in life. 3D dissections on geometrically precise reconstructions allows the interpretation of previously unusable specimens and reinterpretation of already described fossils. Further, use of Simpleware’s software to convert repaired fossils into micron level finite element meshes will enable the biomechanical testing of these repaired structures. Testing of fossil structure and function is already underway at the University of Manchester and is adding to our knowledge of extinct animals.