Edentata


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Edentata

A group of mammals that encompasses several orders of unusual fossil and living animals characterized by reduced or strongly modified teeth. Usually included in this group are the order Pholidota, the pangolins or scaly anteaters of Africa and Southeast Asia; the order Xenarthra, the true anteaters, armadillos, sloths, and their relatives derived mainly from South and Central America; and the extinct Palaeanodonta, an early Cenozoic group of burrowing mammals from North America. The term “edentate” means toothless. Historically a wide range of toothless mammals and mammals with reduced dentition have been incorporated in this taxonomic group, among them aardvarks and echidnas. Modern systematists restrict the term to pholidotans, xenarthrans, and palaeanodonts based on several shared anatomical specializations found exclusively in these three taxa. Only the pangolins and the true anteaters lack teeth entirely, but all edentates are characterized by a reduced dentition. Typically the incisor teeth are lacking, the tooth enamel is strongly reduced or absent (although enamel is retained in a few of the early fossil forms and in the embryos of living armadillos), and tooth replacement is lost. All three groups share digging adaptations, and specializations for feeding on ants and termites. In addition, pangolins and some xenarthrans have a scaly external body covering. Some mammalian systematists have suggested that edentates represent one of the most primitive groups of living placental mammals, although the matter is somewhat controversial. See Tooth

Edentata

 

an order of mammals. These animals range in length from 12 cm (lesser pichiciego) to 120 cm (giant anteater); their weight ranges from 90 g to 55 kg (giant armadillo). The body is densely covered with coarse or silky fur. In armadillos, the top of the head, body, and tail is covered with a shell of large bony and horny hinged plates. The rootless teeth are not differentiated and lack enamel; there are no incisors or canines. Anteaters have no teeth. The anterior limbs are adapted for climbing trees and digging: the highly developed second and third toes have powerful sicklelike claws. Some species (sloths) have six to nine cervical vertebrae.

The order Edentata comprises three families: Myrmecophagidae (anteaters), Bradypodidae (sloths), and Dasypodidae (armadillos). There are 14 genera, with 30 species; these are distributed in South and Central America and in the southern part of North America. Edentates inhabit arid open regions, savannas, and tropical forests. There are terrestrial, fossorial, and arboreal forms.

The Edentata are crepuscular and nocturnal animals. They feed on both animal substances (invertebrates and small vertebrates) and plant substances. These mammals reproduce once a year. The gestation period, which usually has a latent period, lasts 120 to 260 days. There are usually up to four young in a litter; armadillos sometimes bear as many as 12 monozygotic young.

Fossil remains of numerous representatives of seven extinct families of Edentata are known from the Late Eocene in South America and from the Late Pliocene in North America. The fossils include the following giant forms: Megatherium, Mylodon, and Glyptodontidae. The majority of edentates are commercially hunted for their meat. Some species have become rare and are protected.

REFERENCE

Zhizn’zhivotnykh, vol. 6. Moscow, 1971.

O. L. ROSSOLIMO

Edentata

[‚ē‚den′tä·də]
(vertebrate zoology)
An order of mammals characterized by the absence of teeth or the presence of simple prismatic, unspecialized teeth with no enamel.
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