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Discovery of the rare and exotic Buffalopterus pustulosus from the Late Silurian of Ontario Canada In the Summer of 2018, while digging for eurypterids in the Williamsville Formation at Ridgemount Quarries in Stevensville, Ontario Canada a most unusual carapace was uncovered. This fossil was identified as Buffalopterus pustulosus (Chelicerata, Eurypterida) in Figure 1. James Hall in 1859 first reported the occurrence of Eurypterus pustulosus from a single fragmentary fossil, however, the most important characteristics were clearly defined, that is the form of head, the position of the lateral eyes, and the fantastic yet extraordinary pustules covering the carapace. Pohlman in the late 1800’s inaccurately described a similar carapace believing it to be a different species. He then studied another fossil (Fig. 2) consisting of post-abdomen tergites (body segments) concluding again that it was not E. pustulosus but instead belonged to the same species as his carapace. Pohlman assigned this genus to the pterygotids. Clarke and Rudemann (1912) determined that indeed all the fossils were synonymous and that the species represented was P. buffaloensis = Buffalopterus pustulosus. Hence, B. pustulosus is known from only a few fragmentary fossils. It is unclear as to what the entire animal looked like as no complete specimens nor identifiable appendages belonging to the species have ever been found. The carapace discovered by me is remarkable not only for its size but flawless preservation. The length of the head is 12 cm (4.75 in.) with a width of 19.0 cm (7.5 in.). The length of the entire animal is estimated to have been as much as 1 meter. Unfortunately, no other parts of the exoskeleton were found. Incredibly, a second, smaller carapace was found by another person a few weeks later but again no other body parts were recovered. Parts of the specimens were donated to the Yale Peabody Museum. Moreover, the late, Sam Ciurca believes the discoveries may represent the first known occurrence of the eurypterid in the Canadian Williamsville. It is interesting to speculate the morphology of B. pustulosus if a complete animal were ever found. Were the swimming legs equipped with paddles so typical of the eurypterids? What were the chelicerae like? Were they small and aligned with the mouth or did they become very large formidable grasping organs similar to the pterygotids with their large cheliceral claws? What was the shape of the abdomen? Was it covered by pustules like the head? Were the pustules simply ornamentation or did they serve another function? How about the telson, was it thin and straight or was it curved? Paleontologists may never know the true answers to these questions of a most aberrant sea scorpion. References Clarke, J.M. and Rudemann, R. 1912. The Eurypterida of New York. New York State Museum Memoir 14, vol 1-2. Fig. 1. Buffalopterus pustulosus carapace from the Late Silurian, Stevensville, Ontario Canada discovered by me. Fig. 2. Post abdomen body segments of Pterygotus globicaudatus Pohlman from the Buffalo Natural Science Museum, Buffalo, NY

I had a very good day collecting last Friday just going through some of the material now. I think I may have found the head and first two somites of a pterygotid. This was found in Bertie Dolestone of the Williamsville formation. This is late Silurian in age. I had to back the matrix with epoxy as it was literally paper thin in spots and ther was a hole besides the head that is filled with epoxy I was thinking it is a pterygytus because the head and body are much smaller (thinner) than the other eurypterids lacustris that I found. Any expert out there want to take a guess. Only time will tell if it continues back under the matrix. The reverse of the slab it is on is just covered with bits of Eurypterids.

I spent the day Friday hunting for Eurypterids. I was pleasantly surprised when I found what I believe to be the tail and last segment of a phyllocarid. Definately looks like the picture in my book "Fossil Ecosystems of North America" This was found in Bertie Dolestone of the Williamsville formation. This is late Silurian in age. Based on the commonest phylocarid in this formation being ceratiocaris acuminata, I suspect that is what I have here. The tail spike appears to be adjsacent to the last segment which is outlined with a black fine sharpie. The tail section itself is 67 millimeters in length. Basically unprepped just a quick dust to get some of the crud off. Here is a close up of the tail Here is a diagram I found