Restricted to North and South America, didelphids have radiated into a wide variety of forms. Most are omnivorous or carnivorous. Several species are arboreal; one is aquatic and has fully webbed hind feet. Didelphids can be found in most habitats from sea level to over 3000m, from dry thornscrub and grassland to tropical forest. The extinct relatives of didelphids were even more varied in their morphology and habits; one group specialized as large carnivores, with one species actually resembling sabre-toothed cats, while another group apparently converged on kangaroo rats and other desert rodents.
Didelphids have a full complement of teeth (five upper and four lower incisors on each side of the jaw, one canine, three premolars, and four molars). Opossums are small to medium in body size; all have five digits on fore- and hindfeet, with the first toe on the hindfoot partially opposable; all digits except the first toe on the hindfoot have claws (it has a nail). The tail is long, scaley, and prehensile in most species. Other characteristics are described under the order Didelphimorphia.
Phil Myers (author), Museum of Zoology, University of Michigan-Ann Arbor.
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.
uses smells or other chemicals to communicate
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.
having the capacity to move from one place to another.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate