The species-level diversity of fossil Chelicerata is summarized for each order. 1952 valid species of fossil chelicerates are currently recognized, of which 1593 are arachnids. In order of abundance they are: Araneae (979 fossil species), Actinotrichida (283), Eurypterida (241), Scorpiones (111), Xiphosura (96), Trigonotarbida (71), Pseudoscorpiones (38), Phalangiotarbida (30), Opiliones (25), ...