Kangaroos and their kin are characterized by large powerful hind limbs. (This is the inspiration for the scientific name of the family: Macropodidae). Some of the large kangaroo species are capable of speeds up to 88 km/h (55 MPH) for short distances. Species in this family can be a small as a hare or as big as an adult human. Found primarily in Australia (including Tasmania) and New Guinea, kangaroos occupy the same ecological niche as large grazing animals such as antelopes, deer and bison do in North America, South America and Africa. Kangaroo teeth are particularly adapted to their diet of tough grasses. The grinding molars erupt in slow succession over the life of the animal and move forward along the jaw, eventually falling out. This process allows the kangaroo to cope with its highly abrasive diet by bringing new teeth into action over time. If the teeth were retained for a long period of time, eventually the grinding required to chew the plants would wear the teeth down. Kangaroos are not greatly bothered by predators, apart from humans and occasional dingoes. As a defensive tactic, a larger kangaroo will often lead its pursuer into water where, standing submerged to the chest, the kangaroo will attempt to drown the attacker under water. In other adversarial circumstances a kangaroo will back against a tree and kick with clawed hind feet at the adversary, sometimes with enough force to kill an adult human.