Acknowledgements We want to thank Andrea Cardini for the invitation to contribute to this issue. The data in Figs. 4 and 5 were collected by Sarah Freidline. We thank Peter Brugger for access to the human brain MRI scans used in Fig. 2 and 3. Comments and suggestions by two expert referees helped improve the manuscript. Abstract Quantitative shape analysis using geometric morphometrics is based on the statistical analysis of landmark coordinates. Many structures, however, cannot be quantified

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... ing traditional landmarks. Semilandmarks make it possible to quantify two or three-dimensional homologous curves and surfaces , and analyse them together with traditional landmarks. Here we first introduce the concept of sliding semilandmarks and discuss applications and limitations of this method. In a second part we show how the sliding semilandmark algorithm can be used to estimate missing data in incomplete specimens.