Book excerpt: Special Publication 485 About 40 million years after the Cambrian Explosion, the Great Ordovician Biodiversification Event (GOBE) represents a second and dramatic burst in marine biodiversity, with major changes in the structure of ecosystems and the progressive replacement of the distinctive Cambrian Evolutionary Fauna by the Paleozoic Evolutionary Fauna. However, the GOBE is not a single, worldwide, short-term event, but rather the complex sum of successive diversifications occurring in distinct taxonomic groups, trophic guilds and regions. This book focuses on the Late Ordovician Tafilalt Biota, Anti-Atlas Morocco, which provides a snapshot of the GOBE in high-latitude regions of the Southern Hemisphere. A series of contributions explore different aspects of the Tafilalt Biota, including its geological setting, the international fossil trade in this area and a series of detailed systematic contributions describing many new taxa of marine invertebrates. This volume represents a significant contribution to the understanding of the Tafilalt Biota and its significance to the GOBE.