Overview NOW is a global database of fossil mammal occurrences, currently containing around 70, 000 locality-species entries. The database spans the last 66 million years, with the primary focus on the last 23 million years. Whereas the database contains a record on all continents, the main focus and coverage of the database historically have been on Eurasia. The database covers a large part of the mammalian fossil record known to research, focusing on classical and actively researched fossil localities. It is run by a management team in collaboration with an international advisory board of experts. Rather than a static archive, the database emphasizes the continuous integration of new knowledge of the community, continuous data curation, and consistency of scientific interpretations. The database records species occurrence at localities worldwide, as well as ecological characteristics of fossil species, geological contexts of localities and more. The database is primarily used for two purposes: for queries about other occurrences of particular taxa, their properties and the properties of localities in the spirit of an encyclopedia; and for large scale research and quantitative analyses of evolutionary processes, patterns, reconstructing past environments, as well as interpreting evolutionary contexts. Accessing the data The NOW data are fully open, requiring no logging in nor a community membership is necessary for using the data for any purpose. Now data can be accessed from www.nowdatabase.org/now/database/. The most updated data can be downloaded directly from the NOW user interface. In addition, archived versions are available. Citation Minimum required attribution Data (https://nowdatabase.org/now/database/) by The NOW Community / CC BY 4.0. http://doi.org/10.5281/zenodo.4268068 Suggested citation or attribution The NOW Community [year]. New and Old Worlds Database of Fossil Mammals (NOW). Licensed under CC BY 4.0. Retrieved [download date] from https://nowdatabase.org/now/database/. http://doi.org/10.5281/zenodo.4268068