Brown Rat vs Common Fat-tailed Mouse Opossum

Rattus norvegicus compared with Thylamys pusillus

Taxonomic Classification

Rank	Brown Rat	Common Fat-tailed Mouse Opossum
Kingdom same	Animalia (สัตว์)	Animalia (สัตว์)
Phylum same	Chordata (สัตว์มีแกนสันหลัง)	Chordata (สัตว์มีแกนสันหลัง)
Class same	Mammalia (สัตว์เลี้ยงลูกด้วยน้ำนม)	Mammalia (สัตว์เลี้ยงลูกด้วยน้ำนม)
Order	Rodentia (อันดับสัตว์ฟันแทะ)	Didelphimorphia (Didelphimorphia)
Family	Muridae (Mice & Rats)	Didelphidae
Genus	Rattus	Thylamys
Species	Rattus norvegicus	Thylamys pusillus

Evolutionary Relationship

Brown Rat and Common Fat-tailed Mouse Opossum share a common ancestor at the Class level: Mammalia. (สัตว์เลี้ยงลูกด้วยน้ำนม)

Conservation Status

Brown Rat

LC — Least Concern

Common Fat-tailed Mouse Opossum

LC — Least Concern

Physical Characteristics

Attribute	Brown Rat	Common Fat-tailed Mouse Opossum
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Brown Rat

Habitat

Found across multiple habitat types including tropical and subtropical moist broadleaf forests, tropical and subtropical dry broadleaf forests, and tropical and subtropical grasslands and savannas, among 10 distinct biome types. Populations are also found in montane and highland environments at higher elevations.

Range

Widely distributed across Africa (11 countries), Asia (15 countries), Europe (41 countries), North America (16 countries), Oceania and the Pacific (10 countries), and South America (10 countries).

Common Fat-tailed Mouse Opossum

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Brown Rat

Brown Rat (Rattus norvegicus) is classified as Least Concern (LC) on the IUCN Red List. Widespread and abundant across its range, with stable populations and no immediate conservation concerns.

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.