Canadian beaver vs Common Fat-tailed Mouse Opossum

Castor canadensis compared with Thylamys pusillus

Key Differences

• Canadian beaver is Not Evaluated while Common Fat-tailed Mouse Opossum is Least Concern.

Taxonomic Classification

Rank	Canadian beaver	Common Fat-tailed Mouse Opossum
Kingdom same	Animalia (动物界)	Animalia (动物界)
Phylum same	Chordata (脊索动物门)	Chordata (脊索动物门)
Class same	Mammalia (哺乳動物)	Mammalia (哺乳動物)
Order	Rodentia (啮齿目)	Didelphimorphia (负鼠目)
Family	Castoridae (Beavers)	Didelphidae
Genus	Castor (Beavers)	Thylamys
Species	Castor canadensis	Thylamys pusillus

Evolutionary Relationship

Canadian beaver and Common Fat-tailed Mouse Opossum share a common ancestor at the Class level: Mammalia. (哺乳動物)

Conservation Status

Canadian beaver

NE — Not Evaluated

Population: ~15.0M

Trend: Stable →

Common Fat-tailed Mouse Opossum

LC — Least Concern

Physical Characteristics

Attribute	Canadian beaver	Common Fat-tailed Mouse Opossum
Diet	Herbivore	—
Average Lifespan	15 years	—
Average Length	1.0 m	—
Average Weight	25.0 kg	—

Habitat & Geographic Range

Canadian beaver

Habitat

Typically found in grasslands, forests, and vegetated habitats.

Range

Widely distributed across Europe (15 countries), North America (United States), and South America (Argentina, Chile).

Common Fat-tailed Mouse Opossum

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Canadian beaver

北美最大的啮齿动物加拿大河狸体重可达32公斤，是栖息于加拿大和美国北部河流、湖泊和湿地的杰出生态系统工程师。通过伐木和建造可达数百米的水坝形成水塘，为数百种物种提供生境。其巢穴和运河改变了整个流域。曾因毛皮贸易被猎杀至濒临灭绝，但种群已大幅恢复。

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.