Common Fat-tailed Mouse Opossum vs Fake round ray

Thylamys pusillus compared with Urotrygon simulatrix

Key Differences

• Common Fat-tailed Mouse Opossum is Least Concern while Fake round ray is Vulnerable.

Taxonomic Classification

Rank	Common Fat-tailed Mouse Opossum	Fake round ray
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Chordata (Chordates)	Chordata (Chordates)
Class	Mammalia (Mammals)	Elasmobranchii
Order	Didelphimorphia (Didelphimorphia)	Myliobatiformes (Myliobatiformes)
Family	Didelphidae	Urotrygonidae
Genus	Thylamys	Urotrygon
Species	Thylamys pusillus	Urotrygon simulatrix

Evolutionary Relationship

Common Fat-tailed Mouse Opossum and Fake round ray share a common ancestor at the Phylum level: Chordata. (Chordates)

Conservation Status

Common Fat-tailed Mouse Opossum

LC — Least Concern

Fake round ray

VU — Vulnerable

Physical Characteristics

Attribute	Common Fat-tailed Mouse Opossum	Fake round ray
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Common Fat-tailed Mouse Opossum

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Fake round ray

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.