Peccaries likely evolved from the Suidae, and are first known from late Eocene or early Oligocene deposits in Europe. Tayassuid fossils have been found in Asia, Africa, and both North and South America, but peccaries are known only from the Americas after the Miocene.

The Tayassuidae are omnivorous, but tend to rely more heavily on plant material than the Old World Suidae. The stomach is two chambered as in the Suidae, but is more complex. The ability of peccaries to utilize varied food sources (coupled with a reduced number of competitors) has allowed this family to expand into a variety of habitats, including arid deserts, dense tropical forests, and open scrubland. They are gregarious, associating in flexible groups with up to around 50 animals, but temporary groupings may include several hundred individuals.

The feet of the Tayassuidae are slender, with four toes on the forefeet but only two (Catagonus) or three (Tayassu, Pecari) toes on the hind feet. The tail has 6-9 caudal vertebrae, compared to 20+ in the Suidae. All peccaries have a bristly coat, with a mane of erectile hairs running from the crown of the head to the rump. A scent gland is located on the back just above the tail, and is used in mutual grooming. The skull has a virtually straight profile. Peccaries possess a nasal disc very similar to suids. The canines are nearly straight and are directed slightly outward - the upper and lower canines slide against each other, stabilizing the jaw when cracking nuts and simultaneously sharpening the teeth into effective weapons. The dental formula for all species is I 2/3, C1/1, P 3/3, M 3/3 x 2 = 38.