Simpsonitheria
Simpsonitheria est infraordinis mammalium marsupialium exstincta.

Systema taxinomicum Animalis 
 Imperium: Eucaryota
 Regnum: Animalia
 Gradus: Metazoa
 Subgradus: Eumetazoa
 Subregnum: Bilateria
 Infraregnum: Eucoelomata
 Supraphylum: Deuterostomia
 Infraphylum: Chordonia
 Phylum: Chordata
 Subphylum: Vertebrata
 Infraphylum: Gnathostomata
 Supraclassis: Tetrapoda
 Infraclassis: Amniota
 Ramus: Mammaliaformes
 Classis: Mammalia
 Subclassis: Theriiformes
 Infraclassis: Holotheria
 Supralegio: Trechnotheria
 Legio: Cladotheria
 Sublegio: Zatheria
 Infralegio: Tribosphenida
 Supracohors: Theria
 Cohors: Marsupialia
 Magnaordo: Ameridelphia
 Ordo: Paucituberculata
 Infrordo: † Simpsonitheria

Classificatio 
 Infraordo †Simpsonitheria				
 Superfamilia †Argyrolagoidea				
 Familia †Gashterniidae
 Genus †Gashternia (Simpson, 1935)
 Familia †Argyrolagidae				
 Genus †Argyrolagus (Ameghino, 1904)		
 Genus †Hondalagus (Marshall & Villaroel, 1988)
 Genus †Microtragulus(Ameghino, 1904)
 Genus †Proargyrolagus (Wolff, 1984)
 Familia †Groeberiidae				
 Subfamilia †Groeberiinae				
 Genus †Groeberia (Patterson, 1952)
 Subfamilia †Patagoniinae				
 Genus †Patagonia (Charlini & Pascual, 1987) 
 Genus †Klohnia (Flynn & Wyss, 1999)
 Suprafamilia †Caroloameghinioidea
 Familia †Glasbiidae				
 Genus †Glasbius (Clemens, 1966)
 Familia †Caroloameghiniidae				
 Genus †Caroloameghinia (Ameghino, 1901)
 Genus †Chulpasia (Crochet & Sigé, 1993)
 Genus †Procaroloameghinia (Marshall, 1982)
 Genus †Robertbutleria (Marshall, 1987)

Marsupialia