Julien Benoit and Sandra C. Jasinoski (2016)
Picking up the pieces: the digital reconstruction of a destroyed holotype from its serial section drawings.
Palaeontologia Electronica 19.3.3T: 1-16
Serial grinding, a popular but destructive technique in the early twentieth century, allows for the detailed tomographic study of vertebrate fossils. Specimen BP/1/1821 (formerly BPI/1/346) is a procynosuchid cynodont (Therapsida) that underwent serial grinding by A.S. Brink in 1961, resulting in a detailed and insightful study of its skull anatomy. However, BP/1/1821 was also designated by Brink as the holotype, and only specimen, of a new (now a junior synonym of Procynosuchus delaharpeae) species of cynodont: ‘Scalopocynodon gracilis’. This species has subsequently been recognised as a junior synonym of Procynosuchus delaharpeae, but the destruction of a holotype remains an irreversible loss. Brink built an enlarged wax model from the serial sections, but it is degrading rapidly. In this article, we explain how we retrieved Brink’s original drawings of the sections, and how we were able to build a new digital model of this specimen using a scanner, virtual stack alignment, and 3D imaging. Comparison with previously published drawings demonstrates the accuracy of this digital model. With a 3D printer, we then re-created a more accurate replication of BP/1/1821 with resin. This life-sized replica now helps to complete the collections of the Evolutionary Studies Institute (University of the Witwatersrand, Johannesburg, South Africa) and replaces the long lost original specimen. The possibility to re-use these old data for palaeontological research is also addressed.