Common Fat-tailed Mouse Opossum vs common opossum

Thylamys pusillus compared with Didelphis marsupialis

Taxonomic Classification

Rank	Common Fat-tailed Mouse Opossum	common opossum
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Chordata (Chordates)	Chordata (Chordates)
Class same	Mammalia (Mammals)	Mammalia (Mammals)
Order same	Didelphimorphia (Didelphimorphia)	Didelphimorphia (Didelphimorphia)
Family same	Didelphidae	Didelphidae
Genus	Thylamys	Didelphis
Species	Thylamys pusillus	Didelphis marsupialis

Evolutionary Relationship

Common Fat-tailed Mouse Opossum and common opossum share a common ancestor at the Family level: Didelphidae.

Conservation Status

Common Fat-tailed Mouse Opossum

LC — Least Concern

common opossum

LC — Least Concern

Physical Characteristics

Attribute	Common Fat-tailed Mouse Opossum	common opossum
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Common Fat-tailed Mouse Opossum

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

common opossum

Habitat

Inhabits tropical and subtropical moist broadleaf forests within the Neotropic biogeographic realm.

Range

Found across North America (Dominica, Grenada, Saint Lucia) and South America (Colombia, Ecuador, Venezuela).

Common Fat-tailed Mouse Opossum

The Common Fat-tailed Mouse Opossum (<em>Thylamys pusillus</em>) is a small marsupial belonging to the genus Thylamys within the family Didelphidae. Like other members of its genus, this species typically stores fat in its tail, which becomes swollen during periods of food abundance and is metabolised during leaner times, a physiological adaptation that provides energy reserves. <em>Thylamys pusillus</em> is generally found in diverse terrestrial and aquatic ecosystems, often in dry woodlands, scrublands, and grassland habitats of South America. The species is assessed as Least Concern on the IUCN Red List, indicating it is not currently considered at risk of extinction. Detailed geographic range data are not available in the current record, but members of this genus are typically distributed across parts of Argentina, Bolivia, Paraguay, and Uruguay. Biological traits including average lifespan, body dimensions, and specific dietary composition remain poorly documented in the scientific literature, though Thylamys species are generally considered omnivorous, often consuming insects, small vertebrates, and plant material.

common opossum

<em>Didelphis marsupialis</em> is a medium-sized marsupial in the family Didelphidae, widely distributed across the Neotropical region, including Colombia, Ecuador, Venezuela, Dominica, Grenada, and Saint Lucia. It inhabits tropical and subtropical moist broadleaf forests, often occurring near human settlements, gardens, and agricultural edges across lowland and montane zones. As a generalist omnivore, this species typically consumes fruits, invertebrates, small vertebrates, carrion, and refuse, making it one of the most adaptable mammals in its range. The common opossum is nocturnal and arboreal, using a prehensile tail for balance and grip while foraging in trees and shrubs. Females give birth to highly altricial young that develop in the marsupium, a defining trait of marsupial reproduction. The IUCN currently classifies this species as Least Concern, reflecting its broad distribution, behavioral flexibility, and tolerance of disturbed habitats. Biological traits such as average lifespan, body length, and body weight are not consistently recorded across populations in standardized databases, and detailed dietary studies remain poorly documented at scale. Its ecological role includes seed dispersal and control of invertebrate populations.