mesothlae was a giant spider of the carboniforis. it was in reptile's beginnings,the second episode of walking with was the size of a human head and had deadly venom in its fangs as shown when one female kills a petrolactosaurus in reptile's beginnings. however,in a forest fire the mesothelae was killed itself and the tables turned beacuse the remaining petrolactosaurus ate it.please add image if you can. thank you.