There were a few species of these gigantic, armored footballs in Mongolia, including Pinacosaurus (above), Tarchia and Saichania. They measured 15 to 23 feet long, their tails ended in a bony club and they probably weighed a few tons. All the ankylosaurs were equipped with an odd fan of tooth, and large hyoid bones, which would support a large tongue: They may have been plant-eaters or ant-eaters.