Common Fat-tailed Mouse Opossum vs koala

Thylamys pusillus compared with Phascolarctos cinereus

Key Differences

• Common Fat-tailed Mouse Opossum is Least Concern while koala is Vulnerable.

Taxonomic Classification

Rank	Common Fat-tailed Mouse Opossum	koala
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Chordata (Chordates)	Chordata (Chordates)
Class same	Mammalia (Mammals)	Mammalia (Mammals)
Order	Didelphimorphia (Didelphimorphia)	Diprotodontia (Marsupials)
Family	Didelphidae	Phascolarctidae (Koalas)
Genus	Thylamys	Phascolarctos (Koalas)
Species	Thylamys pusillus	Phascolarctos cinereus

Evolutionary Relationship

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

Conservation Status

Common Fat-tailed Mouse Opossum

LC — Least Concern

koala

VU — Vulnerable

Population: ~100.0K

Trend: Decreasing ↓

Physical Characteristics

Attribute	Common Fat-tailed Mouse Opossum	koala
Diet	—	Herbivore
Average Lifespan	—	15 years
Average Length	—	75 cm
Average Weight	—	10.0 kg

Habitat & Geographic Range

Common Fat-tailed Mouse Opossum

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

koala

Habitat

Typically found in grasslands, forests, and vegetated habitats.

Range

Found in Australia. Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

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.

koala

Iconic marsupial of eastern and southeastern Australia, koalas weigh up to 15 kg and spend up to 22 hours daily sleeping to conserve energy from their low-calorie eucalyptus leaf diet. Highly specialized to process toxic eucalyptus compounds that would kill most other mammals, they have gut microbiomes uniquely adapted for detoxification. Listed as Endangered in 2022, with populations decimated by chlamydia disease, habitat clearing, and climate change.