Bison Antiquus Fossil Vertebrae. This is a fossil vertebrae that belonged to a large bull Bison antiquus occidentalis that was recovered from Anoka County, Minnesota USA it's approximately 18 inches long by approximately 4 inches at the vertebral disc. The species of this Bison is known due to the fact that several intact skulls were found at this location. This is a peat bog find. Fossils in this location are from the Pleistocene Epoch. It was originally found by Patrick T. Cherney.