armadillo [key], New World armored mammal of the order Edentata, a group that also includes the sloth and the anteater, characterized by peglike teeth without roots or enamel. Armadillos are found from Argentina to Panama, with one species reaching the southern United States. The head and body of an armadillo are almost completely covered by an armor of plates made of bone and horny material; the plates are separated by soft skin which bears a few hairs. The body armor, or carapace, hangs down on either side of the animal's body and is divided into flexible bands across the back. Members of some armadillo species can roll into a ball for protection. Armadillos are omnivorous, although insects form the bulk of their diet. Most are nocturnal, resting during the day in burrows that they excavate with their strong front feet and enormous claws; they can dig into the ground with amazing speed when threatened. There are 21 armadillo species, classified in 9 genera. The largest is the giant armadillo, Priodontes giganteus, which reaches 4 ft (120 cm) in length and may weigh 100 lb (45 kg). Members of this species have almost 100 teeth, more than any other mammal. Despite their great bulk, they are able to stand on their hind feet and sometimes walk in this position. This species inhabits the Amazonian forest; most other armadillos are grasslands dwellers. The smallest armadillos are the fairy armadillos, or pichiagos; the smaller of the two pichiago species (Chlamyphorus truncatus) is about 6 in. (15 cm) long and bright pink in color, with plumes of white hair about the face and undersides and between the front and back portions of the shield. The nine-banded armadillo, Dasypus novemcinctus, is the only species found in the United States; it ranges from Argentina to Texas and Louisiana. It is about 30 in. (76 cm) long and 6 in. (15 cm) high at the shoulder; it weighs about 15 lb (6.4 kg). It normally moves about slowly, but is very swift when threatened. Each animal has several burrows. Females of this species almost always give birth to identical quadruplets. Armadillos are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Edentata, family Dasypodidae.
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