Dasyproctidaeacuchis and agoutis

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This family contains 13 species in 2 genera. Restricted to tropical parts of the New World, it includes some fairly common and sometimes conspicuous forest residents. It is an unfortunate and potentially confusing accident of taxonomy that agoutis do not belong to the family Agoutidae, which instead contains their relatives, the pacas.

Dasyproctids are moderately large, up to around 2 kg in weight. They have slender and graceful bodies supported by very thin and long legs. The hind limbs are notably longer than the forelimbs. The head is large, ears small and rounded but conspicuous, and eyes large. Four digits are found on each forefoot, but the fourth is reduced in size. The hind feet are 3-toed. All digits have sharp, hoof-like claws, and walking and running are digitigrade. Agoutis have a very short tail, while that of acouchis is longer.

The pelage of members of this family is coarse but has a distinct glossy sheen. The hairs over the rump are especially long. Their color varies from nearly black to yellowish brown on the back, with the underparts generally paler, and the long hairs over the rump may be contrastingly colored.

The skulls of agoutis and acouchis are more elongate and not nearly as robust as those of the related pacas. A sagittal crest may be present. The premaxillae and nasals project forward well beyond the incisors. The zygomatic arches are relatively delicate, without any trace of the expanded plate that characterizes pacas. The auditory bullae are not especially inflated, and paroccipital processes are of moderate size also. Dasyproctids are hystricognathous and hystricomorphous; the infraorbital canal is fairly large, and it lacks a separate groove for carrying nerves.

The dental formula of agoutis and acouchis is 1/1, 0/0, 1/1, 3/3 = 20. The cheekteeth of members of this family are hypsodont and flat-crowned. Their surface includes several re-entrant folds, which soon are isolated as islands as the teeth wear. Incisors are relatively delicate.

These animals are usually solitary, but they are occasionally seen in small groups around concentrations of food. They are generalist herbivores, consuming fruits, nuts, succulent plants, leaves, and even roots. They can be serious pests around peanut and cassava crops. Dasyproctids are fast and manueverable runners, resembling small antelope in some ecological and behavioral traits. Like pacas, they are treasured by hunters for their tender and mild flavored meat.

The fossil record of this family extends to the early Oligocene.

References and literature 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.

Macdonald, David. 1984. The encyclopedia of mammals. Facts on File Publications, New York.

Nowak, R. M. and J. L. Paradiso. 1983. Walker's mammals of the world. The Johns Hopkins University Press, Baltimore and London, pp 803-810.

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 (eds.). 1993. Mammal species of the world: A taxonomic and geographic reference, 2nd ed.. Smithsonian Institution Press, Washington and London.

Woods, C. A. 1984. Hystricognath rodents. Pp. 389-446 in Anderson, S. and J. K. Jones, Jr. (eds.). Orders and familes of mammals of the world. John Wiley and Sons, New York.

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