How Many Species of Fossil Arachnids are There?(Report‪)‬

Harvey (2002: table 1) reported a total--to December 2000--of 97,682 valid species of Recent Arachnida; with the caveat that many more probably remain to be described. But how many species of fossil arachnids are there? Older figures of 366 valid fossil arachnid species names can be culled from Scudder (1891) and, some sixty years later, Petrunkevitch (1955: 48) had cataloged 505. Since that time there have been important developments in our understanding of arachnid paleontology (see, e.g., Selden 1993). New localities continue to yield new species, while amber spiders (e.g., Wunderlich 2004) have proved to be the major source of new names in recent years. That said, revision of historical types usually lowers diversity once synonyms or erroneously assigned fossils have been recognized. Here, we offer a modern summary of crude fossil arachnid diversity (Table 1) and the most important localities (Table 2) as a baseline for future paleoarachnological research. 1593 valid fossil arachnid species are recognized here from 1776 published names. For completeness we have expanded our review to cover the entire Chelicerata, resulting in a grand total of 1952 valid fossil species from 2283 published names. METHODS