I found this diving in the Peace River, Polk County Florida in 2013. After identification by Dr. Hulbert, he mentioned that they did not have an example of that bone in the state collection, and that they would love to have it if I ever wanted to donate it. After five years of consideration, I realized last week that it would be put to much better use there than in my living room. I mailed it last week.
Glyptotherium sp.
Florida Museum of Natural History (UF)
tibia and fibula are fused at the proximal and distal ends (Engelmann, 1985).
Bone Valley formation
Peace River, Polk County, Fla river alluvial deposit on hard bottom rock.