Armadillo

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Armadillo
Temporal range: 58.7–0  Ma
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Late Paleocene – Recent
Nine-banded Armadillo.jpg
Nine-banded armadillo (Dasypus novemcinctus)
Scientific classification
Kingdom:
Phylum:
Class:
Superorder:
Order:
Families

Chlamyphoridae
Dasypodidae

Nine-banded armadillo skeleton. Nine-banded armadillo skeleton.jpg
Nine-banded armadillo skeleton.
Three-banded armadillo skeleton on display at the Museum of Osteology. Three Banded Armadillo.jpg
Three-banded armadillo skeleton on display at the Museum of Osteology.

Armadillos (from Spanish "little armoured one") are New World placental mammals in the order Cingulata. The Chlamyphoridae and Dasypodidae are the only surviving families in the order, which is part of the superorder Xenarthra, along with the anteaters and sloths. Nine extinct genera and 21 extant species of armadillo have been described, some of which are distinguished by the number of bands on their armour. All species are native to the Americas, where they inhabit a variety of different environments.

New World Collectively, the Americas and Oceania

The New World is one of the names used for the majority of Earth's Western Hemisphere, specifically the Americas, and Oceania.

Mammal class of tetrapods

Mammals are vertebrate animals constituting the class Mammalia, and characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex, fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles and birds, from which they diverged in the late Triassic, 201–227 million years ago. There are around 5,450 species of mammals. The largest orders are the rodents, bats and Soricomorpha. The next three are the Primates, the Cetartiodactyla, and the Carnivora.

In biological classification, the order is

  1. a taxonomic rank used in the classification of organisms and recognized by the nomenclature codes. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family. An immediately higher rank, superorder, may be added directly above order, while suborder would be a lower rank.
  2. a taxonomic unit, a taxon, in that rank. In that case the plural is orders.

Contents

Armadillos are characterized by a leathery armour shell and long sharp claws for digging. They have short legs, but can move quite quickly. The average length of an armadillo is about 75 cm (30 in), including tail. The giant armadillo grows up to 150 cm (59 in) and weighs up to 54 kg (119 lb), while the pink fairy armadillo has a length of only 13–15 cm (5–6 in). When threatened by a predator, Tolypeutes species frequently roll up into a ball.

Armour (anatomy) anatomical feature

Armour or armor in animals is external or superficial protection against attack by predators, formed as part of the body, usually through the hardening of body tissues, outgrowths or secretions. It has therefore mostly developed in 'prey' species.

Giant armadillo A species of mammals belonging to the armadillo order of xenarthrans

The giant armadillo, colloquially tatou, ocarro, tatu-canastra or tatú carreta, is the largest living species of armadillo. It lives in South America, ranging throughout as far south as northern Argentina. This species is considered vulnerable to extinction.

Pink fairy armadillo A species of mammals belonging to the armadillo order of xenarthrans

The pink fairy armadillo or pichiciego is the smallest species of armadillo, first described by Richard Harlan in 1825. This desert-adapted animal is endemic to central Argentina and can be found inhabiting sandy plains, dunes, and scrubby grasslands.

Etymology

The word armadillo means "little armoured one" in Spanish. The Aztecs called them āyōtōchtli [aːjoːˈtoːt͡ʃt͡ɬi] , Nahuatl for "turtle-rabbit": āyōtl [ˈaːjoːt͡ɬ] (turtle) and tōchtli [ˈtoːt͡ʃt͡ɬi] (rabbit). [1] The Portuguese word for "armadillo" is tatu which derives from the Tupi language. [2] Similar names are also found in other, especially European, languages.

Aztecs Ethnic group of central Mexico and its civilization

The Aztecs were a Mesoamerican culture that flourished in central Mexico in the post-classic period from 1300 to 1521. The Aztec peoples included different ethnic groups of central Mexico, particularly those groups who spoke the Nahuatl language and who dominated large parts of Mesoamerica from the 14th to the 16th centuries. Aztec culture was organized into city-states (altepetl), some of which joined to form alliances, political confederations, or empires. The Aztec Empire was a confederation of three city-states established in 1427, Tenochtitlan, city-state of the Mexica or Tenochca; Texcoco; and Tlacopan, previously part of the Tepanec empire, whose dominant power was Azcapotzalco. Although the term Aztecs is often narrowly restricted to the Mexica of Tenochtitlan, it is also broadly used to refer to Nahua polities or peoples of central Mexico in the prehispanic era, as well as the Spanish colonial era (1521–1821). The definitions of Aztec and Aztecs have long been the topic of scholarly discussion, ever since German scientist Alexander von Humboldt established its common usage in the early nineteenth century.

Nahuatl, known historically as Aztec, is a language or group of languages of the Uto-Aztecan language family. Varieties of Nahuatl are spoken by about 1.7 million Nahua peoples, most of whom live in central Mexico.

Portuguese language Romance language that originated in Portugal

Portuguese is a Western Romance language originating in the Iberian Peninsula. It is the sole official language of Portugal, Brazil, Cape Verde, Guinea-Bissau, Mozambique, Angola, and São Tomé and Príncipe. It also has co-official language status in East Timor, Equatorial Guinea and Macau in China. As the result of expansion during colonial times, a cultural presence of Portuguese and Portuguese creole speakers are also found in Goa, Daman and Diu in India; in Batticaloa on the east coast of Sri Lanka; in the Indonesian island of Flores; in the Malacca state of Malaysia; and the ABC islands in the Caribbean where Papiamento is spoken, while Cape Verdean Creole is the most widely spoken Portuguese-based Creole. Reintegrationists maintain that Galician is not a separate language, but a dialect of Portuguese. A Portuguese-speaking person or nation is referred to as "Lusophone" (Lusófono).

Classification

Pink fairy armadillo Pink Fairy Armadillo (Chlamyphorus truncatus) (cropped).jpg
Pink fairy armadillo

Family Dasypodidae

<i>Dasypus</i> A genus of mammals belonging to the armadillo order of xenarthrans

Dasypus is the only extant genus in the family Dasypodidae. Its species are known as long-nosed or naked-tailed armadillos. They are largely found in South, Central, and North America. Dasypus are solitary mammals that are primarily nocturnal to avoid temperature extremes and predation. They exist in numerous habitats ranging from brush to grassland areas and are mainly insectivorous.

Nine-banded armadillo species of medium-sized mammal

The nine-banded armadillo, or the nine-banded, long-nosed armadillo, is a medium-sized mammal found in North, Central, and South America, making it the most widespread of the armadillos. Its ancestors originated in South America, and remained there until the formation of the Isthmus of Panama allowed them to enter North America as part of the Great American Interchange. The nine-banded armadillo is a solitary, mainly nocturnal animal, found in many kinds of habitats, from mature and secondary rainforests to grassland and dry scrub. It is an insectivore, feeding chiefly on ants, termites, and other small invertebrates. The armadillo can jump 3–4 ft (91–122 cm) straight in the air if sufficiently frightened, making it a particular danger on roads. It is the state small mammal of Texas.

Seven-banded armadillo species of armadillo found in Paraguay, Argentina, Bolivia and Brazil.

The seven-banded, long-nosed armadillo or just seven-banded armadillo, Dasypus septemcinctus, is a species of armadillo from South America found in Paraguay, Argentina, Bolivia and Brazil. It is a solitary nocturnal, terrestrial animal, living mostly in dry habitats, outside of rainforest regions.

Family Chlamyphoridae

† indicates extinct taxon

Phylogeny

Below is a recent simplified phylogeny of the xenarthran families, which includes armadillos, based on Slater et al. (2016) [4] and Delsuc et al. (2016). [5] The dagger symbol, "†", denotes extinct groups.

Xenarthra
Cingulata

Dasypodidae (Armadillos)

Pampatheriidae

Chlamyphoridae (Armadillos)

Pilosa
Vermilingua

Cyclopedidae

Myrmecophagidae

Folivora

Megatheriidae

Nothrotheriidae

Bradypodidae

Mylodontidae

Megalonychidae

Evolution

Recent genetic research suggests that an extinct group of giant armoured mammals, the glyptodonts, should be included within the lineage of armadillos, having diverged some 35 million years ago, much more recently than previously assumed. [6]

Distribution

Like all of the Xenarthra lineages, armadillos originated in South America. Due to the continent's former isolation, they were confined there for most of the Cenozoic. The recent formation of the Isthmus of Panama allowed a few members of the family to migrate northward into southern North America by the early Pleistocene, as part of the Great American Interchange. [7] (Some of their much larger cingulate relatives, the pampatheres and chlamyphorid glyptodonts, made the same journey.) [7]

Today, all extant armadillo species are still present in South America. They are particularly diverse in Paraguay (where 11 species exist) and surrounding areas. Many species are endangered. Some, including four species of Dasypus , are widely distributed over the Americas, whereas others, such as Yepes's mulita, are restricted to small ranges. Two species, the northern naked-tailed armadillo and nine-banded armadillo, are found in Central America; the latter has also reached the United States, primarily in the south-central states (notably Texas), but with a range that extends as far east as North Carolina and Florida, and as far north as southern Nebraska and southern Indiana. [8] Their range has consistently expanded in North America over the last century due to a lack of natural predators.

Characteristics

Size

Armadillos are small to medium-sized mammals. The smallest species, the pink fairy armadillo, is roughly chipmunk-sized at 85 g (3.0 oz) and 13–15 cm (5.1–5.9 in) in total length. The largest species, the giant armadillo, can be the size of a small pig and weigh up to 54 kg (119 lb), and can be 150 cm (59 in) long. [9]

Diet and predation

They are prolific diggers. Many species use their sharp claws to dig for food, such as grubs, and to dig dens. The nine-banded armadillo prefers to build burrows in moist soil near the creeks, streams, and arroyos around which it lives and feeds. The diets of different armadillo species vary, but consist mainly of insects, grubs, and other invertebrates. Some species, however, feed almost entirely on ants and termites.

Paws of a hairy and a giant armadillo Mani armadilli.png
Paws of a hairy and a giant armadillo

Armadillos have very poor eyesight, and use their keen sense of smell to hunt for food. [9] They use their claws for digging and finding food, as well as for making their homes in burrows. They dig their burrows with their claws, making only a single corridor the width of the animal's body. They have five clawed toes on their hind feet, and three to five toes with heavy digging claws on their fore feet. Armadillos have a large number of cheek teeth which are not divided into premolars and molars, but usually have no incisors or canines. The dentition of the nine-banded armadillo is P 7/7, M 1/1 = 32. [10]

Body temperature

In common with other xenarthrans, armadillos, in general, have low body temperatures of 33–36 °C (91–97 °F) and low basal metabolic rates (40–60% of that expected in placental mammals of their mass). This is particularly true of types that specialize in using termites as their primary food source (for example, Priodontes and Tolypeutes ). [11]

Skin

The armour is formed by plates of dermal bone covered in relatively small, overlapping epidermal scales called "scutes", composed of bone with a covering of horn. Most species have rigid shields over the shoulders and hips, with a number of bands separated by flexible skin covering the back and flanks. Additional armour covers the top of the head, the upper parts of the limbs, and the tail. The underside of the animal is never armoured, and is simply covered with soft skin and fur. [12]

This armour-like skin appears to be the main defense of many armadillos, although most escape predators by fleeing (often into thorny patches, from which their armour protects them) or digging to safety. Only the South American three-banded armadillos (Tolypeutes) rely heavily on their armour for protection.

Defensive behavior

When threatened by a predator, Tolypeutes species frequently roll up into a ball. Other armadillo species cannot roll up because they have too many plates. The North American nine-banded armadillo tends to jump straight in the air when surprised, so consequently often collides with the undercarriage or fenders of passing vehicles to its demise. [13]

Movement

Armadillos have short legs, but can move quite quickly. The nine-banded armadillo is noted for its movement through water [14] which is accomplished via two different methods: it can walk underwater for short distances, holding its breath for as long as six minutes; also, to cross larger bodies of water, it is capable of increasing its buoyancy by swallowing air, inflating its stomach and intestines. [15]

Reproduction

Gestation lasts from 60 to 120 days, depending on species, although the nine-banded armadillo also exhibits delayed implantation, so the young are not typically born for eight months after mating. Most members of the genus Dasypus give birth to four monozygotic young (that is, identical quadruplets), [16] but other species may have typical litter sizes that range from one to eight. The young are born with soft, leathery skin which hardens within a few weeks. They reach sexual maturity in three to twelve months, depending on the species. Armadillos are solitary animals that do not share their burrows with other adults. [12]

Armadillos and humans

In science

Disease

Armadillos are often used in the study of leprosy, since they, along with mangabey monkeys, rabbits, and mice (on their footpads), are among the few known species that can contract the disease systemically. They are particularly susceptible due to their unusually low body temperature, which is hospitable to the leprosy bacterium, Mycobacterium leprae . (The leprosy bacterium is difficult to culture and armadillos have a body temperature of 34 °C (93 °F), similar to human skin.) [17] Humans can acquire a leprosy infection from armadillos by handling them or consuming armadillo meat. [18] Armadillos are a presumed vector and natural reservoir for the disease in Texas and Louisiana and Florida. [19] [20] Prior to the arrival of Europeans in the late 15th century, leprosy was unknown in the New World. Given that armadillos are native to the New World, at some point they must have acquired the disease from old-world humans. [18] [20]

The armadillo is also a natural reservoir for Chagas disease. [21]

Reproduction

The nine-banded armadillo also serves science through its unusual reproductive system, in which four genetically identical offspring are born, the result of one original egg. [22] [23] [24] Because they are always genetically identical, the group of four young provides a good subject for scientific, behavioral, or medical tests that need consistent biological and genetic makeup in the test subjects. This is the only reliable manifestation of polyembryony in the class Mammalia, and exists only within the genus Dasypus and not in all armadillos, as is commonly believed. Other species that display this trait include parasitoid wasps, certain flatworms, and various aquatic invertebrates. [23]

Education

Armadillos (mainly Dasypus) are common roadkill due to their habit of jumping 3–4 ft vertically when startled, which puts them into collision with the underside of vehicles. Wildlife enthusiasts are using the northward march of the armadillo as an opportunity to educate others about the animals, which can be a burrowing nuisance to property owners and managers. [22]

As musical instruments

Armadillo shells have traditionally been used to make the back of the charango , an Andean lute instrument.

Related Research Articles

Xenarthra Superorder of mammals that diversified in South America

Xenarthra is a superorder of placental mammals found in the Americas. It currently consists of anteaters, tree sloths and armadillos. Xenarthrans originated in South America during the Paleocene about 59 million years ago. They evolved and diversified extensively in South America during the continent's long period of isolation in the early to mid Cenozoic Era. They spread to the Antilles by the early Miocene and, starting about 3 Mya, spread to Central and North America as part of the Great American Interchange. Nearly all of the formerly abundant megafaunal xenarthrans, such as ground sloths, glyptodonts and pampatheres, became extinct at the end of the Pleistocene.

Cingulata order of mammals

Cingulata, part of the superorder Xenarthra, is an order of armored New World placental mammals. Dasypodids and chlamyphorids, the armadillos, are the only surviving families in the order. Two groups of cingulates much larger than extant armadillos existed until recently: pampatheriids, which reached weights of up to 200 kg (440 lb) and chlamyphorid glyptodonts, which attained masses of 2,000 kg (4,400 lb) or more.

Six-banded armadillo A species of mammals belonging to the armadillo order of xenarthrans

The six-banded armadillo, also known as the yellow armadillo, is an armadillo found in South America. The sole extant member of its genus, it was first described by Swedish zoologist Carl Linnaeus in 1758. The six-banded armadillo is typically between 40 and 50 centimeters in head-and-body length, and weighs 3.2 to 6.5 kilograms. The carapace is pale yellow to reddish brown, marked by scales of equal length, and scantily covered by buff to white bristle-like hairs. The forefeet have five distinct toes, each with moderately developed claws.

Southern naked-tailed armadillo species of mammal

The southern naked-tailed armadillo is a species of small armadillo from South America.

Greater naked-tailed armadillo species of mammal

The greater naked-tailed armadillo is an armadillo species from South America.

Andean hairy armadillo species of mammal

The Andean hairy armadillo is an armadillo located in Bolivia, in the region of the Puna; the departments of Oruro, La Paz, and Cochabamba. Nowark (1991) describes it as distributed in Bolivia and northern Chile. A recent publication of Pacheco (1995) also locates the species in Peru, basically in Puno Region. This species is also thought to be present in northern Argentina. However, this location may actually only contain a population of C. vellerosus.

Northern naked-tailed armadillo species of mammal

The northern naked-tailed armadillo is a species of armadillo. It is one of only two species of armadillo found outside of South America, the other being the more widely distributed nine-banded armadillo.

Big hairy armadillo species of mammal

The big hairy armadillo or large hairy armadillo or “enormous hairy armadillo”(Chaetophractus villosus) is one of the largest and most numerous armadillos in South America. It lives from sea level to altitudes of up to 1,300 meters across the southern portion of South America, and can be found in grasslands, forests, and savannahs, and has even started claiming agricultural areas as its home. It is an accomplished digger and spends most of its time below ground. It makes both temporary and long-term burrows, depending on its food source. The armadillo can use specially evolved membranes in its nose to obtain oxygen from the surrounding soil particles without inhaling any of the soil itself. Armadillos are protected from predators by a series of thin, bony plates along the head and back. They reach sexual maturity at around 9 months and have been known to live over 30 years in captivity. Though this animal is routinely harvested for its meat and its shell, or simply killed for pestering farmers, it has shown amazing resiliency, and populations seem to be handling this exploitation well. Currently, no protective practices are in place for this armadillo, but it does live in many protected areas. This species of armadillo is a preferred research animal due to its adaptability to laboratory settings, and relative hardiness in situations of stress.

Tolypeutinae subfamily of mammals

Tolypeutinae is a subfamily of armadillos in the family Chlamyphoridae, consisting of the giant, three-banded and naked-tailed armadillos. The subfamily is the sister group of Chlamyphorinae, the fairy armadillos. It contains the following genera:

Chlamyphoridae family of mammals

Chlamyphoridae is a family of cingulate mammals. While glyptodonts have traditionally been considered stem-group cingulates outside the group that contains modern armadillos, there had been speculation that the extant family Dasypodidae could be paraphyletic based on morphological evidence. In 2016, an analysis of Doedicurus mtDNA found it was, in fact, nested within the modern armadillos as the sister group of a clade consisting of Chlamyphorinae and Tolypeutinae. For this reason, all armadillos but Dasypus were relocated to a new family.

References

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Further reading