Nine-banded armadillo (Dasypus novemcinctus) alongside with opossum (Didelphis) and American porcupines (Erethizon) was one of the most successful descendants of South American fauna settled to the north in time of “Great Interchange” in Plio-Pleistocene. In human epoch this species had overcome Mexican plateau and was settled rather far to the north, having successfully mastered the south of the United States of America. During the ice age at the boundary of Holocene and Neocene armadilloes among other thermophilic animals had receded to the south, but with the subsequent warming they have returned to former positions again.
Nagual, the large species of armadilloes, lives at the southern border of prairies where the grassy vegetation is gradually replaced by water-stocking succulents and deciduous prickly bushes. It is large enough representative of family: its length is about 130 cm, and weight reaches 100 kg and more. The big size of animal is one of ways of survival in desert: the large animal has the big stocks of water in organism, and the strong armour protects not only from enemies, but also from the hot sun. At the north of the area nagual leads a day time habit of life, but at the south, in deserts of Mexico, activity is displaced to night time. It is also a way to avoid overheat and losses of water. The armour of animal consists of two strong plates – forward and back ones – and between them some belts of cornificated skin with elastic sites between them are located. Under armour there is a layer of fat which is the heat insulator. As against the ancestor, nagual is not able to turn off in ball. Being attacked by predator, animal simply lays on the ground, having turned up under armour head and thick short tail. Because of large weight it is difficult to turn it, but if predator manages to do it, animal protects itself, sharply waving forepaws armed with sharp claws. The bottom part of animal body is covered with rough yellowish wool. Armour is colored bright yellow with grayish shade. The head of animal is covered with strong corneous plate with skin ossifications which jut out on plate surface like rounded outgrowths. Eyes are small – nagual has bad sense of sight. Animal has mobile rounded ears which are penetrated with blood vessels and partly help to radiate the surplus of heat. Muzzle of nagual is short and triangular; teeth are numerous and have sharp cutting edge. They are closed in such a manner that edges of upper and lower teeth are constantly erased against each other. On teeth of upper jaw cutting edge is external, on lower jaw internal. Despite of size and slowness nagual is zoophagous species. It willingly eats carrion searching it by smell. Nagual is frequently fed with the rests of prey of local predators. Due to massive armour this animal does not pay attention to attempts of predator to protect the prey. Furthermore nagual eats medium-sized vertebrates and occasionally feeds on underground and sapful parts of plants, especially during the drought season. Forepaws of nagual are perfectly adapted to digging. The third and fourth fingers are armed with huge claws – about 7 cm thick and up to 18 – 20 cm long. On scapulae ledges and crests to which strong muscles attach are advanced. Nagual easily moves the stones comparable in weight to the animal and can dig and throw out on ground surface up to half of cubic metre of the ground in some minutes. Defending itself against enemies, the animal drops to the ground and sticks claws into it deeply. In that case it is very difficult to turn nagual upside down. But if the predator had made it, the animal defends, making sharp attacks by claws. If it succeeds to grasp a predator, this armadillo seizes it in death grip and can easily strangle it or break its ribs. Therefore, when nagual appears near prey, lucky hunters prefer not to pay attention to this one. The sexual dimorphism at this species is not expressed. Pregnancy is long because of latent stage: it proceeds till about 11 months, and cubs always are born in favorable season. Up to 10 cubs may be born; they have the same gender because develop from one initial ovocyte. Newborn armadilloes have opened eyes and are covered with soft leathery armour. In some hours after birth they are already capable to walk, and in same time the armour hardens quickly. Young animals remain with mother within 8 months. They reach sexual maturity in 4 years.