Isometroides vescusCollection Highlights | Updated 6 years ago Isometroides vescus Image copyright of WA Museum Scorpions are an ancient group of animals with fossils dating back over 400 million years. The Australian fauna consists of as much as 200 different species, many of which are currently unnamed. Not much is known about the provenance of this specimen, although it was collected in the Greenough area during 1850-1880 by F.W. Pearson. It is the oldest specimen in the Museum’s arachnology collection. Arachnid and Myriapod Collection View the discussion thread.