Table 1. Summary of the main taxonomic proposals for early SANUs (‘condylarths’), Litopterna, and Notopterna. Abbreviations: SF, Superfamily; SO, Suborder

Ameghino (1889)	Lydekker (1893)	Ameghino (1904a)	Ameghino (1906)	Schlosser (1911)	Scott (1913)
aGelfo et al. (2016) argued that Protolipternidae may be a junior synonym of Didolodontidae,which in turn may be a form of bunodont litoptern.
Ungulata	Order Ungulata	Order Condylarthra	Order Condylarthra	Order Ungulata	Order Litopterna
Perissodactyla	SO Litopterna	Fam. Phenacodontidae	Fam. Pantostylopidae	SO Litopterna	Fam. Macraucheniidae
Order Litopterna	Fam. Macraucheniidae	Fam. Periptychidae	Fam. Phenacodontidae	Fam. Bunolitopternidae	Fam. Proterotheriidae
Fam. Macraucheniidae	Fam. Proterotheriidae	Fam. Pantolambdidae	Fam. Catathleidae	Fam. Macraucheniidae	Fam. Didolodidae
Fam. Proterotheriidae		Fam. Pantostylopidae	Fam. Pantolambdidae	Fam. Proterotheriidae
Fam. Homalodontotheriidae		Order Perissodactyla	Fam. Arctocyonidae	Fam. Adianthidae
		Fam. Macrauchenidae	Order Perissodactyla
		Subfam. Theosodontinae	Fam. Hyracotheriidae
		Subfam. Macraucheninae	Fam. Palaeotheriidae
		Fam. Adiantidae	Fam. Macraucheniidae
		Fam. Proterotheriidae	Fam. Proterotheriidae
		Fam. Hyracotheriidae	Fam. Adiantidae
		Fam. Lophiodontidae
Simpson (1945)	Cifelli (1983a)	McKenna and Bell (1997)	Soria (1989a, 2001)	Muizon and Cifelli (2000) Gelfo et al. (2016)
Order Condylartha	Order Condylarthra	Order Condylarthra	Order Condylarthra	Order Panameriungulata Panperissodactyla
Fam. Didolodontidae	SF Didolodontoidea	Fam. Didolodontidae	Fam. Didolodontidae	Fam. Mioclaenidae	Order Panameriungulata
Order Litopterna	Fam. Didolodontidae	Order Litopterna	Order Litopterna	Subfam. Kollpaniinae	Subfam. Kollpaniinae
Fam. Macraucheniidae	Fam. Sparnotheriodontidae	Fam. Protolipternidae	SO Eolitopterna	Fam. Didolodontidae	Fam. Didolodontidae?a
Subfam. Macraucheniinae	Order Litopterna	SF Macrauchenoidea	Fam. Anisolambdidae	SO Litopterna	Order Litopterna
Subfam. Adianthinae	Fam. Protolipternidae	Fam. Macraucheniidae	Fam. Sparnotheriodontidae Fam. Protolipternidae		Fam. Didolodontidae? (=
Fam. Proterotheriidae	SO Lopholipterna	Subfam. Sparnotheriodontinae	SO Lopholipterna	Fam. Macrauchenidae	Protolipternidae)a
Subfam. Polymorphinae	SF Macrauchenoidea	Subfam. Polymorphinae	Fam. Macraucheniidae	Fam. Adianthidae	Fam. Protolipternidae
Subfam. Proterotheriinae	Fam. Macraucheniidae	Subfam. Cramaucheniinae	Subfam. Macraucheniinae	Fam. Proterotheriidae	Fam. Anisolambdidae
	Subfam. Polymorphinae	Subfam. Macraucheniinae	Subfam. Cramaucheniinae	Fam. Notonychopidae	Fam. Sparnotheriodontidae
	Subfam. Cramaucheniinae	Fam. Notonychopidae	Fam. Proterotheriidae		Fam. Macraucheniidae
	Subfam. Macraucheniinae	Fam. Adianthidae	Fam. Adianthidae		Fam. Proterotheriidae
	Fam. Adianthidae	Subfam. Indaleciinae	Order Notopterna		Fam. Adianthidae
	SF Proterotherioidea	Subfam. Adianthinae	Fam. Amilnedwarsiidae		Fam. Notonychopidae
	Fam. Proterotheriidae	SF Proterotherioidea	Fam. Indaleciidae
	Subfam. Anisolambdinae	Fam. Proterotheriidae	Fam. Notonychopidae
	Subfam. Proterotheriinae	Subfam. Anisolambdinae
		Subfam. Proterotheriinae