Pangolins were classified with various other orders, for example Xenarthra, which includes the ordinary anteaters, sloths, and the similar-looking armadillos. But newer genetic evidence indicates that their closest living relatives are the Carnivora, with which they form the clade Ferae. Some paleontologists have classified the pangolins in the order Cimolesta, together with several extinct groups.
he physical appearance of pangolins is marked by large, hardened, plate-like scales. The scales, which are soft on newborn pangolins but harden as the animal matures, are made of keratin, the same material of which human fingernails and tetrapod claws are made. The pangolin is often compared to a walking pine cone or globe artichoke. It can curl up into a ball when threatened, with its overlapping scales acting as armour and its face tucked under its tail. The scales are razor-sharp, providing extra defence. The front claws are so long that they are unsuited for walking, and so the animal walks with its fore paws curled over to protect them. Pangolins can also emit a noxious smelling acid from glands near the anus, similar to the spray of a skunk. Pangolins have short legs, with sharp claws which they use for burrowing into termite and ant mounds, as well as climbing.
The size of pangolins varies by species, ranging from 30 cm to 100 cm (12 to 39 inches). Females are generally smaller than males.
The tongues of pangolins are extremely elongated and extend into the abdominal cavity. By convergent evolution pangolins, the giant anteater, and the tube-lipped nectar bat, all have tongues which are unattached from their hyoid bone and extend past their pharynx deep into the thorax. This extension lies between the sternum and the trachea. Large pangolins can extend their tongues as much as 40 cm (16 inches), with a diameter of only 0.5 cm (1/4 inch).
In pangolins, the section of the brain that relates to problem solving is highly developed. Although their problem solving ability is primarily used to find food in obscure locations, when kept in captivity pangolins are remarkable escape artists.
Arboreal pangolins live in hollow trees, whereas the ground dwelling species dig tunnels underground, up to a depth of 3.5 m (11 feet). Pangolins are also good swimmers.
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