Bartail spurdog vs Common Fat-tailed Mouse Opossum

Squalus notocaudatus compared with Thylamys pusillus

Taxonomic Classification

Rank	Bartail spurdog	Common Fat-tailed Mouse Opossum
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Chordata (Chordates)	Chordata (Chordates)
Class	Elasmobranchii	Mammalia (Mammals)
Order	Squaliformes (Squaliformes)	Didelphimorphia (Didelphimorphia)
Family	Squalidae	Didelphidae
Genus	Squalus	Thylamys
Species	Squalus notocaudatus	Thylamys pusillus

Evolutionary Relationship

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

Conservation Status

Bartail spurdog

LC — Least Concern

Common Fat-tailed Mouse Opossum

LC — Least Concern

Physical Characteristics

Attribute	Bartail spurdog	Common Fat-tailed Mouse Opossum
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Bartail spurdog

Common Fat-tailed Mouse Opossum

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Bartail spurdog

The Bartail spurdog (Squalus notocaudatus) is a species in the genus Squalus. It is currently classified as Least Concern on the IUCN Red List.

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.