Potoroidaebettongs, potoroos, and rat kangaroos

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The potoroids are a family of diprotodont marsupials believed to be closely allied with the kangaroos and wallabies (Macropodidae) and sometimes grouped as a subfamily within that family. The Potoroidae includes 9 species placed in 5 genera. They are found in Australia.

Like macropodids, these small and secretive animals are diprotodont and syndactylous. Also like macropodids, they have enlarged hind feet and powerful hind limbs. At high speeds they are adept hoppers. At slower speeds, their movement is more rabbit-like; they land with their weight on their forelimbs as well as hind, then transfer weight to the hindlimbs for the next hop. The forelimbs are smaller than the hindlimbs, but the disparity in size is not as great as in kangaroos and wallabies. As in the case of macropodid hind feet, the fourth toe is the longest and strongest. It sits in a line with main limb elements and transmits thrust of hopping. It is not as well developed, however, as the fourth toe in macropodids. The tail is semiprehensile.

The dental formula of potoroids is 3/1, 1-0/0 2/2, 4/4 = 32-34. The second and third upper incisors are small and placed lateral to and behind the first incisor, not lateral as in macropodids. In other respects, the skull is similar to that of kangaroos. Canines are present and well-developed. The molars are stationary, that is, they don't show pattern of forward movement with aging that is seen in macropodids. Young potoroids and macropodids have two upper and lower premolars that are replaced in adulthood by a single, large, blade-like premolar in both jaws.

Members of this family are omnivores and herbivores, feeding mainly on underground fungi and tubers also taking some seeds and insects. They have a well developed marsupial pouch that opens anteriorly. Their reproductive pattern includes an embryonic diapause like that of macropodids. Their stomachs are less elaborately pouched than those of macropodids; instead, they are unspecialized in some species and with a few simple chambers (with bacterial fermentation) in others.

Several members of this family have not fared well following the European colonization of Australia. Two species are believed to be extinct and two additional species are currently threatened with extinction.

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.

Lawlor, T. E. 1979. Handbook to the Orders and Families of Living Mammals. Mad River Press, Inc., Eureka, California. 327pp.

Marshall, L. G. 1984. Monotremes and marsupials. Pp 59-115 in Anderson, S. and J. Knox Jones, eds, Orders and Families of Recent Mammals of the World. John Wiley and Sons, NY. xii+686 pp.

Strahan, R. (ed.). 1995. Mammals of Australia. Smithsonian Institution Press, Washington, D.C. 756 pp.

Vaughan, T. A. 1986. Mammalogy. Third Edition. Saunders College Publishing, Fort Worth. vi+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