Pyrotherium sorondoi (Ameghino 1889, 1894, 1895; Billet 2010; Early Oligocene, 29-21 mya; 3m long); data here comes only from its skull, but post-cranial pieces are known indicating a graviportal stance. Wikipedia called Pyrotherium an ungulate. Other workers (i.e. Shockley et al. 2004) had trouble nesting it. The skull converges with Arsinoitherium and elephants.

Here Pyrotherium nests as a sister to Toxodon, among the wombat marsupialls, derived from a sister to Vombatus. Pyrotherium emphasized the incisor tusks and had large molars and premolars.

Ameghino F 1889. Contribución al conocimiento de los mamíferos fósiles de la República Argentina, obra escrita bajo los auspicios de la Academia Nacional de Ciencias de la República Argentina para presentarla a la Exposición Universal de Paris de 1889. Actas Academia de Ciencias. de Córdoba 6:1–1027.

Ameghino F 1894. Sur les oiseaux fossiles de Patagonie; et la faune mammalogique des couches à Pyrotherium. Boletin del Instituto Geographico Argentino 15:501-660.

Ameghino F 1895. Premiére contribution à connaissance de la fauna mammalogique de couches à Pyrotherium. Boletín Instituto Geográfico Argentino 15:603–660.

Billet G. 2010. New Observations on the Skull of Pyrotherium (Pyrotheria, Mammalia) and New Phylogenetic Hypotheses on South American Ungulates. Journal of Mammal Evolution. 17:21-59.

wiki/Pyrotherium