Dwarf Mammoth Jaw Cast. Dwarf Mammoth existed until as late as 1650 BCE. These mammoth had become isolated on the Channel Islands off of California, United States. Their average height was 1.7 metres (5.6 Feet) at their shoulders; and, they weighed less than a ton. Dwarf Mammoth Jaw Cast measurement 38 cm x 23 cm x 51 cm (15" x 9" x 20").