SUPREMELY RARE Mazon Creek Uropygid Arachnid Prothylephonus

Description: The Mazon Creek deposits of the region near Braidwood, Illinois rival the other famous Lagerstatten of the Burgess Shale, Solnhofen, and Liaoning for the variety of detailed life preserved. Many exquisitely-preserved specimens are found in the ironstone nodules that make up the deposits. This fine specimen was found recently in Mazon Creek itself, and is of a spider-like arachnid known as Prothylephonus, a member of the uropygids, or whip scorpions. Fossil whipscorpions are quite rare, and currently the Pennsylvanian or North America and Europe, and one from the Cretaceous of Brazil are the only ones known. The uropygids are rare arachnids comprising only 3 % of the total arachnid specimens from Mazon Creek. The Mazon Creek location has yielded some 250 arachnids as of the publication of Richardson’s guidebook, more than any other Paleozoic locality. While most are incomplete, the degree of preservation allows for interpretation of these ancestral creatures. Note that the semi-raptorial pedipalps, several preserved limbs, and the finely segmented abdomen is quite evident in this part/counterpart specimen. Due top the fact that the human eye can perceive detail better than the camera lens, I have included two negative images to make the details more apparent. I have recently been able to procure specimens from a family who has been collecting this material in the field for three generations, and will continue posting material as it becomes available to me.