An exceptionally rare partial American Mastodon (Mammut americanum) leg comprising the ulna and humerus, recovered in the 1960s from the banks of the Peace River, Florida—a noted but challenging locality where large vertebrate fossils seldom survive due to the region’s acidic sediments. Dating to the Pleistocene epoch, the specimen represents a significant and increasingly scarce category of material from an area more commonly associated with Miocene marine deposits and fossil shark teeth, with mammalian remains of this scale encountered far less frequently. The bones are well preserved, substantial in weight, and display strong structural integrity. The humerus is present in two sections, the result of a clean, stable break that could be readily restored if desired. The specimen is mounted on a custom steel museum stand and measures approximately 56" high as displayed, with a base of 21" x 16".