Integrating information from the fossil record allows us to obtain accurate age estimates for important events in the evolutionary history of living species and to study the dynamics of speciation and extinction in more detail. The fossilized birth–death (FBD) process is a widely used model for the diversification of both extinct and extant species. Understanding the behavior of this model and the influence of its different parameters is thus very important for researchers interested in reconstructing the evolutionary history of species through time. Here, we present a web application built around the FBD process that allows users to simulate diversification and fossil sampling and visualize the results. The app can be used as a demonstration and teaching tool, allowing users to experiment with the different components of the model and observe their effect on the results of the simulation. It also helps researchers in designing simulation studies and testing their simulation choices.

Phylogenetic inferences using combined datasets of both extant and extinct species have grown increasingly popular, in part thanks to the development of the fossilized birth–death (FBD) process. The FBD process provides a powerful model for the evolution of past and present lineages and can be used for both inference and simulation. Simulations in particular are very helpful for new users to gain better understanding of the model and its different components. In this work, we present FossilSimShiny, a visual application for simulating phylogenies, fossil samples, and fossil taxonomies under the FBD process. The app integrates a wide range of simulation models and presents the simulation results in clear, customizable figures. As a teaching tool, FossilSimShiny allows lecturers to create illustration plots and students to directly experiment with the model. For research applications, the app can help researchers save time and effort by testing and calibrating simulation setups before running them on a large scale.