Abstract: Two-dimensional (2D) data is the major data type in geometric morphometrics for a long time. 2D data played an important role in the origin and rising of geometric morphometrics. Numerous significant scientific problems have been solved based on 2D data. The super capability of geometric morphometrics in scientific computing and problem solving based on 2D data has been perfectly demonstrated. However, there are still some special scientific problems or specific morphological characters which can not be easily or perfectly investigated via 2D data. Three-dimensional (3D) data on a large scale and in great amount could be a better option for these issues. The needs for 3D geometric morphometrics become more and more urgent. Furthermore, 3D data collecting becomes easier and cheaper and a large quantity of 3D data emerge. Here in this article the principles and application of 3D geometric morphometrics were reviewed. The similarities and differences between 2D and 3D geometric morphometrics are listed. The two development stages of 3D geometric morphometrics, i.e., the morphological simulation and quasi-quantitative comparison of a small-size sample, and quantitative comparison of a large number of samples, are reviewed. The application of four-dimensional data and finite element analysis is evaluated. The development potential of 3D geometric morphometrics in the field of entomology is pointed out. The future directions of 3D geometric morphometrics, such as increasing of sample size, hardware upgrade, increasing of data resolution, development of new algorithms, presentation of results, 3D printing, etc., are proposed.

Key words: Geometric morphometrics, two-dimensional data, three-dimensional data, functional morphology, 3D printing, entomology