Only one opossum reaches the United States and Canada
Opossums make up Didelphimorphia, the Americas’ largest marsupial order—about 126 species in eighteen genera. The Virginia opossum alone reaches the United States and Canada; English shortened a Powhatan word recorded by John Smith and William Strachey around 1607–1611 into everyday possum.
Smith wrote the word as opassom and Strachey as aposoum, both hearing it at Jamestown, which Smith helped found and where Strachey became the first secretary. Strachey likened the animal to a pig in size and taste; Smith gave it a swine's head, a rat's tail and a cat's bulk. The Powhatan word traces back to a Proto-Algonquian term meaning white dog or dog-like beast. English settlers in Australia later borrowed possum for unrelated tree-dwelling marsupials closer to kangaroos. The order's name means two wombs, after the female's paired reproductive tract.
Opossums are often called living fossils, but their oldest fossils date only to the early Miocene, about 20 million years ago. They probably arose in Amazonia and stayed minor players until the late Miocene, when they diversified as rival carnivorous metatherians faded, and they reached North America after the continents joined. Some evolved into predators before true carnivores arrived; the extinct Thylophorops, at 4 to 7 kg, was the largest opossum known.
Living species range up to house-cat size, with long snouts, clawless opposable big toes and, in some, grasping tails. Their 50 teeth make an unusually full jaw for a mammal. Diets vary from the fruit-eating woolly opossums to the meat-eating lutrine opossum, and the yapok, or water opossum, is the only living semi-aquatic marsupial, diving with webbed hind feet for crayfish and molluscs.
Gestation lasts only 12 to 14 days. Litters can number 20, yet at most about 13 newborns manage to latch onto a teat, and they wean after 70 to 125 days. Life is brief: one or two years in the wild, perhaps four in captivity. The Virginia opossum is generally placid and rarely spreads rabies.
Source: Opossum
