Many real world examples can be found that deal with hierarchical data. Software systems typically consist of packages, directories, subdirectories, files, classes, and functions. Phylogenetic trees structure biological species into a hierarchical organization. Visualizing such static hierarchical data has been in focus of Information Visualization for many years. Visually encoding and understanding of evolving hierarchies still remains a challenging task. Since hierarchies may grow huge and

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... evolve over a long time producing many time steps, we make use of a side-by-side and aligned representation of Indented Pixel Tree Plots. To achieve a mental map preserving overview-based diagram we show the dynamics of a hierarchy by a static representation and illustrate the changes between subsequent hierarchies by special links. Interactive features make the data manipulable and navigable in all dimensions.