Largest arachnid ever

The largest species of arachnid currently known to have existed is Brontoscorpio anglicus, a species of giant prehistoric scorpion that existed in what is now Worcestershire, central England, UK, during the Upper Silurian Period, approximately 425 million years ago. It is presently represented only by a single incomplete free finger from a right-hand pedipalp (pincer), but based upon the latter's dimensions, palaeontologists have estimated that the complete creature would have measured at least 90 cm in total length.

This remarkable fossil was discovered in Silurian sandstone from Trimpley in Worcestershire, central England, UK, and its species was formally described and named in 1972.

Its scientific name, Brontoscorpio anglicus, translates as "English thunder scorpion".

The largest current arachnid is a specimen of the giant forest scorpion Heterometrus swammerdami that was found during World War II in the village of Krishnarajapuram, India, and measured 29.2 cm in overall length from the tips of its pedipalps or "pincers" to the end of its sting. This species is from southern India, and males frequently attain a length of more than 18 cm.