What is the largest known spider in prehistory? I guess those with arachnophobia do not want to know. But for everyone else, this question is no longer, at least, interesting to know.
Currently, the spider named Goliath is larger and heavier there. You can reach 30 cm in length with legs extended, although poisonous, is not fatal.
The fossil ever found largest spider is the Nephila Jurassica. A spider bigger than Goliath. Each leg was 15 cm and its body (the females who were older) had a thickness of up to 12 cm. We extended that could reach 42 cm easily.
Nephila Another curiosity is that the oldest fossil spider found. And it was in April 2011 when they discovered their fossils in what is now China.
Another curiosity of this spider is that their fossils belong to the Jurassic and the Carboniferous (when there were large insects that increased much in size by the lack of predators and the high concentration of oxygen in the atmosphere). But hey, that does not mean they do not exist. In fact we think that existed when the land was a continent, Pangea, 1000 million years ago.
Finally, little is known of Jurassica Nephila, sure we'll learn more over time.