Chrysochloridaegolden moles

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Golden moles are fairly common throughout southern Africa, where 7 genera and around 18 species are known. They thrive in habitats ranging from deserts to swamps, where they are generally solitary and territorial. Golden moles dig and live in burrows, eating mainly invertebrates that they find underground. They appear similar to both the Talpidae ("true" moles) and the Notoryctidae (marsupial "moles") in that they have small ears that are hidden by their fur, short tails, and eyes are totally covered by skin. Large leathery pads on their noses probably help them to burrow through the ground, as do their short, powerful forearms and claws.

Golden moles are also unusual in that both males and females have a single opening (a cloaca) for the urogenital system. The skull is conical in outline. They have a pair of bones, called tabulars, in the occipital area of the skull, which are not found in other mammals. The zygomatic arches are formed by elongations of the maxillae. The malleus is tremendously enlarged, and it has been suggested that this actually aids hearing under ground (that is, the detection of ground-born vibrations). Golden moles have no fifth finger on their front paws, and most species have a huge claw on the third (and sometimes also the second) digit. Their fur has a beautiful iridescent sheen.

The dental formula of chrysochlorids is 3/3, 1/1, 3/3, 2-3/2-3 = 36-40. The first incisor is enlarged; the two lateral incisors and first premolars are canine-like; and the molars are zalambdodont.

Golden moles burrow mainly using their leathery snout combined with thrusts of the forepaws, which are held under the body (rather than at the sides, as in the talpids). They are powerful and adept burrowers.

Chrysochlorids are known from Miocene deposits, but because these fossils resemble modern members of the family, they tell us little about the origins of the group. Recent molecular evidence suggests that they and tenrecs should be separated from the Insectivora and placed in a grouping of African mammals, the Afrotheria, which includes elephants, hyraxes, sea cows, elephant shrews, and aardvarks as well as golden moles and tenrecs (Murphy et al. 2001).

Technical characters

References and literature cited:

Murphy, W.J., E. Eisirik, S.J. O'Brian, O. Madsen, M. Scally, C.J. Douady, E. Teeling, O.A. Ryder, M.J. Stanhope, W.W. de Jong, and M.S. Springer. 2001. Resolution of the early placental mammal radiation using Bayesian phylogenetics. Science 294238-2351.

Macdonald, D., ed. 1984. The Encyclopedia of Mammals. New York, Facts On File Publications.

Nowak, R.M., and J.L. Paradiso. 1983. Walker's Mammals of the World, 4th ed., Vol. I. Baltimore, Johns Hopkins University Press.

Vaughan, T.A. 1972. Mammalogy. Philadelphia, W.B. Saunders Co.

Yates, T. L. 1984. Insectivores, elephant shrews, tree shrews, and dermopterans. Pp. 117-144 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.

Contributors

Deborah Ciszek (author), University of Michigan-Ann Arbor, 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