Pholidotapangolins

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Pangolins are a small group (seven living species placed in one genus and one family, Manidae) of mammals that feed mostly on ants. They are found in the tropical regions of Africa and Asia.

Pangolins are conspicuous and remarkable because their backs are covered with large, overlapping scales made up of agglutinated hairs. But they are strange in other ways as well. Their tongue is extraordinarily long and muscular, arising from the pelvis and the last pair of ribs deep in the animal's chest. As a result, the tongue and associated muscles are longer than the animal's head and body, allowing the tongue to be extruded to an astonishing degree. Pangolins lack teeth. Instead, the the pyloric part of their stomach is thickened and muscular, with odd keratinous spines projecting into its interior. It usually contains pebbles and seems to be used for "chewing" in much the same way as a bird's gizzard. Pangolins have the ability to close their ears and nostrils as well as eyes, presumably to keep ants out.

The skull of pangolins is smoothly conical, lacking the ridges and crests found on most mammalian crania. The palate is long, but not as long as the palate of myrmecophagids, and unlike members of that group it does not incorporate the pterygoids. They have no jugal and the zygomatic arch is incomplete. The mandible is narrow and weak. It lacks angular and coronoid processes but has an unusual conical projection at its anterior end on the upper (dorsal) surface.

Externally, the scales extend from the head, down the back to or almost to the tip of the long tail. Beneath, pangolins lack scales but have a sparse coat of fur. Their limbs are stout and well adapted for digging. Claws are large, sharp, and recurved. Pangolins range in size from about 1.6kg to a maximum of about 33kg.

Some species of pangolins are arboreal, others are terrestrial. Two species have semiprehensile tails, used in climbing. Their scales provide good defense against predators. When threatened, pangolins curl into a ball, protecting their scaleless undersurface and sometimes rolling down a steep slope. They lash about dangerously with their tails, which are covered with sharp-edged scales. They may also spray a foul-smelling liquid from their anal glands. Pangolins have relatively poor vision and hearing; they probably locate their prey by scent.

The relationship of pangolins to other groups of mammals is not clear. Their fossil record extends to the Eocene.

Technical characters

Literature and references cited

Feldhamer, G. A., L. C. Drickamer, S. H. Vessey, and J. F. Merritt. 1999. Mammalogy. Adaptation, Diversity, and Ecology. WCB McGraw-Hill, Boston. xii+563pp.

Barlow, J. C. 1984. Xenarthrans and pholidotes. Pp. 219-239 in Anderson, S. and J. K. Jones, Jr. (eds). Orders and Families of Recent Mammals of the World. John Wiley and Sons, N.Y. xii+686 pp.

Savage, R. J. G. and M. R. Long. 1986. Mammal Evolution, an Illustrated Guide. Facts of File Publications, New York. 259 pp.

Vaughan, T. A. 1986. Mammalogy. Third Edition. Saunders College Publishing, Fort Worth. vii+576 pp.

Vaughan, T. A., J. M. Ryan, N. J. Czaplewski. 2000. Mammalogy. Fourth Edition. Saunders College Publishing, Philadelphia. vii+565pp.

Wilson, D. E., and D. M. Reeder. 1993. Mammal Species of the World, A Taxonomic and Geographic Reference. 2nd edition. Smithsonian Institution Press, Washington. xviii+1206 pp.

Contributors

Phil Myers (author), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

motile

having the capacity to move from one place to another.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate