grass hide horn Mud rhino skin square mouth white rhino dangerous Adaptation Grass Eating Rhino. organism rhinoceros safari Square Mouth Rhino terrestrial animal white rhinoceros wildlife african broad-mouthed collagen endangered flat-mouthed gray grazer grey heavy herbivore herbivorous horns keratin large lattice structured mammal megafauna odd-toed ungulate perissodactyl placid powerful snout southern white rhinoceros square-lipped rhinoceros strong thick threatened tough wide-lipped rhinoceros creases folds