By David L. Fox and Phil Myers
Tayassuids are pig-like animals that are found in the southwestern United States, south to central Argentina. Head and body length ranges between 750-1112 mm and the tail, which only has from six to nine vertebrae, ranges from 15-102 mm. Peccaries are covered with coarse grayish or brownish fur, and all species have contrasting areas of white or yellowish fur on their chests, backs, or faces. Each of the three species is currently placed in its own genus: Catagonus wagneri, Pecari tajacu and Tayassu pecari. Tayassuids are known in the fossil record from all continents except Antarctica and Australia, beginning in the Oligocene (37-24 Ma). A fourth genus, Platygonus, was present throughout the contiguous United States until the end of the last Ice Age 12,000 years ago, and a number of other genera have been described.
The snout of peccaries has the same mobile cartilaginous disk and terminal nostrils as pigs. A 
sagittal crest is present, the zygomatic arch is well developed, and an incomplete postorbital bar partially isolates the orbits. Also as in pigs, the median digits of the forefeet and hindfeet are the only functional ones ( paraxonic). However, unlike pigs, the third and fourth metapodials are fused at the proximal end. Tayassu and Pecari have three digits on the hind feet; Catagonus has two. All three genera have a scent gland on the rump, which is used in social communication. The stomach has two or three chambers and is non- ruminating. It is more complex, however, than in that of suids.
The dental formula of the tayassuids is 2/3, 1/1, 3/3, 3/3 = 38 teeth. The upper canines grow into tusks that are smaller than those of the suids. They are directed downward, while those of suids tend to be directed laterally or even upwards. Like those of suids, peccary canines develop sharp cutting edges as a result of wear. The cheek teeth form a continuous series and increase in size toward the back of the jaws. The premolars are increasingly molariform toward the back. The molars are quadrate and bunodont.
Peccaries are gregarious animals; group size ranges from a few animals to several hundred depending on the species and on how heavily hunted they are. They forage during the day, feeding on a wide variety of plant and animal materials.
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.
Nowak, R.M. and J.L. Paradiso. 1983. Walker's Mammals of the World, 4th edition . John Hopkins University Press, Baltimore, MD.
Savage, R. J. G. and M. R. Long. 1986. Mammal Evolution: An Illustrated Guide. Facts on File Publications, UK. 251 pp.
Simpson, C. D. 1984. Artiodactyls. Pp. 563-587 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.
Vaughan, T. A. 1986. Mammalogy. Third Edition. Saunders College Publishing, N.Y. 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.&160;
Contributors
David L. Fox (author), University of Michigan. Phil Myers (author), Museum of Zoology, University of Michigan.
